JBrady

I will not respond to any more header PMs if the person obviously has not read the following.

So many people have PM'd me with questions on the headers. The original thread was massive and most did not take the time to read through it especially with all the unrelated posting.

Therefore, I have pulled all of my posts from the original thread and have created a condensed version with just the pertinent information. It starts at the beginning so reading through it will show the timeline and evolution of the project.

If you are interested in the headers and have questions PLEASE take the time to read through the following. It is a long post but it will take you less time to read through this than it will for me to answer questions one at a time, over and over again.

JBrady

11-23-03, 05:09 PM
Lexus V8 HFVS Shorty Headers. Gathering Commitment for New Design

ClubLexus member JBrady has researched and located a master craftsman that is willing to build shorty headers for our 1UZ-FE V8 engine. He has already built some very nice headers for the 4.7 liter Tundra and is familiar with the construction requirements.

DESIGN: The HFVS Shorty Header
The stock exhaust manifolds are very restrictive. 1990-1997 are the worst with 1998+ cars being slightly better but still poor. It is obvious that better flowing manifolds are needed for true performance. ALL designs have compromises so the challenge is to pick the best design for the application. In my opinion the best design for the Lexus V8 automobiles is a High Flow high Velocity, Scavenging short runner exhaust manifold with merge collectors. aka: HFVS Shorty Header.

The design goal will be to produce a manifold that vastly outflows the factory manifolds and will fit all year and model Lexus V8 cars including:
1992-97 SC400
1998+ SC400
GS400
GS430
1990-97 LS400
1998-00 LS400
The HFVS Shorty headers will be designed as a bolt in for 1998+ V8 cars to keep the catalysts in their stock locations. This will require earlier cars to run aftermarket cats or at least move the stock cats. They will probably also fit the LS430s and SC430s but until they are designed and test fitted we will not know about space limitations for those vehicles.

Pre-1998 cars will require a change in catalysts location. Choices include relocated stock catalysts (under the car), aftermarket catalysts (under the car) or the possible use of 98+ catalysts. An aftermarket cat back exhaust system will be needed. They will also need an EGR flange welded to the header. The EGR flange will be an available option at a cost of approximately $50.

Expected power increase of 20+rwhp and 20+rwtq (probably more).
1998 and newer cars could use these headers with the stock exhaust system but full power gains will require a true high flow cat back exhaust system. On a car with a full complementing exhaust the HFVS Shorty headers are expected to outperform any available long tube design across the full RPM range.

REQUESTED COMMITMENT
Before these headers will be built we need to obtain commitments for 20 sets, NOT PAYMENT, just an agreement to buy them when available. No payment of any kind will be requested prior to the headers actually being designed and built and ready for ordering. ONLY If you know you will want to buy a set when available please send a confidential PM as directed below and you will be updated on progress and expected order dates. As of 11/17/2003 there are commitments for 14 sets of headers. With development and build time the expected availability is February.

NOTE: This is not yet an official group buy item on ClubLexus, but the builder needs to ensure that there is sufficient interest in this item before he moves forward with the design. ClubLexus feels these items will be of sufficient interest and value to our Lexus enthusiast community to gauge early interest of our members in this performance product that does not exist elsewhere. It is important to note that all responsibility for this transaction is with the buyer and the designer (not ClubLexus).

CONSTRUCTION
To keep pricing reasonable the Headers will be constructed of MILD steel (as are Tex's headers). Mild steel is actually less prone to cracking at the welds than stainless and with ceramic coating have a life expectancy of over 10 years. Pricing for the headers WITH Ceramic coating (recommended) should be under $600. Without the ceramic coating around $400 for the set.

DESIGN EXAMPLES
The picture BELOW is the C's headers built in Japan. They are NOT what you should expect rather they give the general idea of the layout of the planned header. In fact the headers below are for the C's 5.5 liter engine and are more show than go. Compared to the HFVS Shorty Headers we are designing they would likely make less power on our engines due to interference between runners and too large of a pipe diameter for our 4.0 and 4.3 liter engines. Again, the image below should help you get a mental picture of the design. The C's headers pictured below cost around $2500.

BELOW is an example of the work of the master craftsman. It is a picture of long tube headers for a Chevrolet but shows some nice work. This example does not use a merge collector but ours will.

PERFORMANCE EXPECTATIONS
As stated above we expect a conservative gain of 20+rwhp and 20+rwtq. Actual output will only be known after construction and testing and will vary depending on year of car installed and other enhancements used.

To get a good idea of what is available in our engines you may wish to look at the below dyno chart.
JBA built shorty headers for the 32 valve 4.7 liter V8 ToyotaTundra... remember, even though it is a 4.7 it is only rated at 245hp @ 4800rpm and 315tq @ 3400. This engine is a close cousin and shares many design elements with the 4.0 and 4.3 liter engines in our Lexus cars.

BELOW is the before and after RWHP dyno charts... remember, this test included a cat back exhaust system as is recommended for our cars. Notice the peak gain of 25rwhp and 38rwtq BUT notice around 4000rpm the gain is around 40rwhp and 50rwtq. Peak gains are good but more important are the gains across the entire RPM range. VERY important and a key goal for our design.

INTERESTED CAR OWNERS
If you appreciate the necessity of good exhaust manifolds to allow your engine to breathe and make the power it should and are interested in obtaining a set of the HFVS Shorty Headers for your car, please do the following.

11-24-03, 12:11 AM
Dave is correct in his responses. Louder should not be much of an issue. These are shortys which like the stock manifolds do not have as much area as long tube headers to resonate so the external sound change should be very small. The rest of the exhaust system will determine how loud the final system is and that will depend on individual muffler choice.

11-24-03, 11:22 AM
PLEASE READ:
Guys, for those wanting in on this deal PLEASE... thoroughly READ the entire 1st post. If you still have questions either post here or PM me. When you understand how important good headers are and have decided to join this project PLEASE fill out the form and PM to me. This allows me to keep track of how many people as well as email with all the updates and details.

As others have pointed out a deposit would be completely reasonable but incredibly not requested. Please respect this and only commit if you plan on buying them when they are built.
I commented already "Louder will not be an issue. These are shortys which like the stock manifolds do not have as much area as long tube headers to resonate so the external sound change should be very small. The rest of the exhaust system will determine how loud the final system is and that will depend on individual muffler choice.

Sound will be VERY close to stock headers EXCEPT under full throttle because they will be flowing more and the engine will be making more power and therefore more sound. BUT... how LOUD the system is will be determined by muffler choice. If you want it quieter you can go with a quieter muffler and vice versa. As the 1st post states... on a GS400 or 98+ LS400/SC400 you can keep the stock exhaust system. Not advised but can be done. These on a stock exhaust system would for all intents be undetectable sound wise.

So, do not let sound worry you. If we get VERY lucky and end up with a 10% power increase, 30hp, there will be 10% more sound at the header collecter at FULL throttle. This 10% goes into the rest of the system and that is marginal. Trust me. I have ran my LS400 with only the cats, the Y pipe and center resonator and it is LOUD. VERY VERY LOUD. It is NOT the headers... it is the exhaust system AFTER the headers. At idle the car sounded like a Corvette, very sweet, at anything more it sounded like a race car.

11-25-03, 09:22 AM
Installation is expected to be difficult. How difficult we will not know until we actually get into the project. On the earlier cars, pre 1998, the installation is much more known as several people have installed the Tex headers from Australia. On post 1998 cars the biggest problem is removing the stock manifolds. A big problem is almost NOBODY has ever done it. Mo at SRT told me over a year ago that the engine needs to be removed

I have worked on MANY MANY engines and believe that we should be able to gain access by removing the motor mounts but NOT the engine. Trust me, I am NOT going to pull my engine. If we find that we must for 1998+ cars... this project will most likely focus on the earlier cars engines. Again, I have a 1999 LS400 and am NOT going to pull my engine but feel that installation can be done from beneath the car on a lift. Remember, we are not taking deposits and therefore nobody is at risk here. We must TRY to fix the problem of restrictive manifolds and this is the WAY to do it.

Again, the unknown installation problem is removing the manifolds from the 1998+ cars. We KNOW that we can remove the manifolds from earlier cars. Once the manifolds are off installation will not be a problem. I personally took pictures of the manifolds from a 1998+ car. You can review some of those pictures here: https://www.clublexus.com/forums/sho...light=manifold

DO NOT let this unknown stop you from committing to a set of headers. You will not be expected to buy anything if the engine needs to be removed. BUT if you UNDERSTAND the importance of these manifolds to allow our cars to remain competitive as Nissan and other manufactures keep releasing faster and faster cars... PLEASE support this effort and sign up for headers. No risk to you at all.

11-25-03, 09:34 AM
You are correct. We are not planning to get these CARB approved at this time. That is an expensive prospect and will need a high product demand to make it reasonable. That said shorty headers for many cars are CARB approved so if we find the demand is there the approval process should be assured.

As pointed out, on a 1998+ the likelyhood of these even being NOTICED is remote. They should not effect the emissions in any way. On earlier cars, people may choose to mount the cats beneath the cars and that could catch a techs attention. Still, this is a low probability but understand that like all non emissions certified parts these will be sold as parts "for off road use only"

I am not an expert on California emissions law but I believe that individual cars can be certified. If someone feels strongly enough about this they could probably have this done. Again, these headers will not effect the emissions on a 1998+ vehicle for the ranges tested.

AS FAR AS the ECU compensating... a 30hp gain would only require a 10% compensation in fuel flow. I am unaware of ANY car coming from the factory with an inability to compensate at least 10%. Engineers must anticipate a range of operating conditions and in fact engineer the ECU programming to be able to adapt to certain extreme operating posibilities. This applies to ALL cars sold. Now if we pick up 100hp we are talking a different game.

11-25-03, 10:52 AM
Good information. I agree that the ability to compensate for a 35% power increase would be unlikely but 10-15% is not a worry.

11-28-03, 01:57 AM
Yes, the Cs headers "look" pretty but if you look closely the tubes actually interfere with each other and that makes for a sub-optimal "working" part. The pictures are not to indicate actual final look just an idea of concept. I suggest you re-read the entire first post and in fact this entire thread as I have addressed the tube length and the installation unkowns. Quickly, no, not equal length nor required for the power we are targeting. Equal length primary tubes are only effective in a small RPM range. The rest of the time it is all about flow, velocity and scavenging. For any value the equal tube style would need primaries neary 3 feet long each and that obviously is not going to be a shorty style header. The shorty design should do very nicely just like the shorty design for the Tundra for which the dyno chart is shown. Installation is not easy, and as yet an unknown. Also, the stock manifolds are tubular not cast iron.

12-01-03, 12:29 AM
Dan, why do you want longer primaries? If you build a long tube equal length header you can create an additional scavenging effect in a narrow RPM band but 6" vs 12" vs 18" is not going to get that effect. What we are wanting is scavenging throughout the RPM range. To do this we want to preserve the velocity and energy of the port. This takes a smallish diameter primary pipe and carefully formed merge areas taking care to keep the collector volume at each merge as small as possible and aerodynamically efficient. After that you get the catalyst which is not much help but required. Then the rest of the exhaust system. If the rest of the system is also designed to scavenge (same principals, larger pipe diameters) the whole system will "pull" from the exhaust ports IOW scavenge. Make sense? If you want tuned equal length headers you will need around 30" primaries to put the "tune" at 6000rpm.

12-03-03, 10:26 AM
Jeff, of course you have already received my direct email reply to your request but I would like to address your above statement "more top-end power without sacraficing any low-end ". Of course this is not meant to retort you as you are very knowledgable on this subject. Rather to help the majority of readers that are not exhaust experts and must rely on what others tell them.

While I agree it is of course theoretically possible to produce a higher power exhaust header/manifold by optimizing the length to the RPM window targeted... the real world situation shows that the added expense, increased installation difficulty and deviation from factory emissions configuration make long tubes a poor choice for 99% of road cars. Also, the KEY to making power is optimizing flow. This a accomplished by creating the lowest possible pressure at the exhaust port during the last half of the exhaust event when in cylinder pressures are dropping rapidly and the pressure differential becomes most important. Long tube headers isolate the individual ports and create a resonance tune effect dictated by tube length and diameter. This tune only happens in a small RPM window. Above and below that RPM the main effect is due to velocity scavenging. Velocity scavenging is the key to the HFVS header and is designed to enhance the effect from low to high rpm. The performance difference between the HFVS and a very well designed ELLT (equal length long tube) design is unlikely to be noticeable from the drivers seat. A poorly designed ELLT will actually hurt performance in various RPM ranges compared to even the FACTORY manifold

I for one would be very unhappy to spend big bucks and make all the sacrifices needed for ELLT only to have a car that is LESS responsive in most driving conditions.

So, for an expert like yourself the ELLT is maybe a reasonable choice but I wanted everyone to understand they are not sacrificing by using the HFVS design with a good cat back secondary system (key to the overall performance of ANY wide RPM operating system).

12-04-03, 10:26 AM
I did not mean to insult you in any way. And I do apologize for I was actually confusing you with someone else that I had just emailed. Also, while you may not consider yourself an expert on header design your experience with 2 strokes and rotaries places you way above the general automotive population regarding exhaust dynamic knowledge.

Am I and expert? That is relative but my exhaust header experience dates to 1978 and I have direct hands on experience in many automotive high performance applications including turbocharging the 12a and 13b rotaries, I4, I5, I6, V6, V8 and V12 engines including 1500hp 510cid twin turbo offshore power boat engines. No one can or ever will know everything about anything so I would never make that claim. I do have some unusual insights and have discussed various designs with many experts including Corky Bell (whom I worked for in 1989-1990), Smokey Yunick (RIP)(30 minute phone conversation regarding his heat expansion cycle engines and the potential of applying it to rotary engines of which he worked with GM on their rotary program that never made production) and Jim Fueling (RIP) back in 1990 who informed me of actually building an engine with a roots supercharger in the exhaust to aid scavenging), and Jack Burns of Burns Stainless who expanded on the functionality of the merge collector, Tom Cloutier who worked with me on computer modeling exhaust flow in multiple configurations for the cat back system I am designing for my LS400, and of course the craftsman who is to build our HFSV headers under whom Jack Burns originally worked prior to founding Burns Stainless. Many, many more but hopefully this will give you an idea. Am I an expert? You can make up your own mind. Truthfully, I am not concerned with that title.

So, my response to your post was sincere and that is why I worded it as such. Did I answer your question on the reason for the shorty design vs a long tube design? If not or if you have any more specific questions I have not addressed feel free to post here or send me a PM or email.

JBrady

12-07-03, 11:02 PM
Here are a couple pics of the PROBLEM... the stock manifolds...
The Passenger side: note the VERY short runners on the back 2 ports and the 90 degree angles




The Driver side is only slightly better with the back 2 ports being the worst.



For more info go here: https://www.clublexus.com/forums/sho...hlight=air+box

12-09-03, 11:16 AM
Fireballs, the exhaust is exiting at tremendous velocities and temperatures. The entire spent exhaust gases have only a few milliseconds to get out of the cylinder. The sharper the turn that must be made the less efficient the manifold becomes. The WORST possible shape is a 90 degree turn. Componding the problem is the construction design that is shown in the below picture... the sharp edges protruding into the gas flow are horrible. Go to the link to read more about this phenomena.

https://www.clublexus.com/forums/sho...highlight=flow

Here is a picture of the stock manifold looking down from the port into the "log". Notice the overhanging sharp edged metal. This goes completely around the port even though just one edge is clearly seen here:



12-09-03, 08:00 PM
Yes. The things to focus on are preserving the energy/velocity while increasing the maximum capacity.
The pipe diameter will be slightly larger than stock but without the horrific bends and sharp edges at intersections and merges.
Look at the above picture and note the sharp edges inside the manifold that protrude into the gas flow. The turbulence caused by this type of aerodynamic interference functionally makes the passage smaller. It also converts flow energy to heat energy. You can see this by looking at the factory dyno picture below and noting the hot spots at each intersection. This loss creates a flow restriction AND has less energy to scavenge. By improving these points we can achieve a significant improvement in flow capacity without lowering velocity or converting flow energy to heat and backpressure.



12-13-03, 11:34 AM
As Wide LS responded we will have to wait until they are built and tested before we can know the actual improvement and what effects other mods in conjuntion with the headers will have. However, a cat back system is highly recommened. On your car it is less necessary than on mine because your center resonator is 60mm (2.36") vs mine at 50mm (1.96") and your single to dual splitting Y section is much better than the LS or SC parts. Your L-Tuned mufflers will be fine with or without changing the rest of the system. A new intake is not necessary either. Remember, an engine is a SYSTEM and all the components effect each others results. The most critical area is the headers on our engine so starting there is a great choice.

01-06-04, 10:32 PM
Well, twice I thought I had located a set of stock manifolds to help facilitate fabrication but that hasn't happened yet. I have had one person in Phoenix offer to R&D with his car but he did not respond to my email for his contact info.
Bottom line, we still need a Phoenix car (cars) and ideally a set of stock 98+ manifolds.
Obviously, installation is still an unknown.
For pre 98 vehicles the hot ticket may be to locate a set of 98+ cats. The ones on my LS are the metal core type which work and flow better than the ceramic core type found on earlier cars. Since the manifolds are longer the cats are shorter to end up at the same basic place under the car. They are also more round than the earlier cats. Of course a pair of high flows under the car would be cheaper than buying cats from the dealer so I am suggesting the possibility of a set of a wrecked car. Otherwise, the set up Peter Scott has would work fine.
Fitment for the SC430 is a total unknown but my guess is a probability.

01-15-04, 05:56 PM
First of all, Thank You VVT-i for getting these numbers

Hmmm... this is curious.
On first glance this looks like they use different manifolds for all these cars... BUT... on second glance I am not so sure. From an engineering standpoint this would be stupid and the Japanese are many things but not stupid.

Oh, regarding the power differences... it is NOT in the exhaust manifold or tuning. It is in the MUCH more restrictive exhaust system of the SC and LS models. In the GS models the dual 50mm (also found on the LS and SC's) join into a 60mm single center resonator and pipe. The LS and SC's have a single 50mm center resonator (less than 2")

Now, back to the manifolds. Notice ALL the left hand manifolds are 17105-50xxx and ALL the right hand manifolds are part number 17104-50xxx. Now, either there are 4 separate designs or for the 98-00 cars Lexus used the part numbers for tracking purposes. Which part needed to be replaced on what car kind of thing.

So, I guess I may try to persuade my local dealer to let me visually check out the various parts (if they even stock them). I believe at the very least they will all have the same flange locations for the heads and catalysts.

01-28-04, 06:05 PM
1st mission accomplished... Picked up a set of factory exhaust manifolds from a 2000 GS400, price, $200
As expected, visually I have yet to notice ANY difference between the LS400 and the GS400 manifolds.
As expected, Lexus/Toyota used the same contruction techniques that I heavily criticized previously. The feed runner meets with a damn created by a sharp edge protruding into the flow. You have heard of antireversion? These are antiflow!!!

Here are some pictures. This first picture shows the new and old sets side by side. You can see how the new ones place the catalyst farther from the engine and therefore would require reworking the catalyst location for early model vehicles.
BTW, the exhaust flanges are an exact match between the early and late manifolds





01-28-04, 06:35 PM
Here is an example of the construction technique that I HATE... the primary connects to the "log" by overlapping a hole cut into the log. This hole is SMALLER than the inside diameter of the primary pipe and this creates a "knife" edge (seen highlighted in white) protruding into the exhaust flow. This is exactly opposite of what you want. Ideally the manifold would flow great but not flow in reverse. This manifold probably flow better in reverse

JBrady

01-29-04, 11:45 AM
Well, the plan was to take pictures, make measurements and then ship them to the fabricator for jigs to be built.

BUT>>> having these parts in my hands has helped IMMENSELY as I can visuallize the task ahead much better. Now, the only car l I have easily available for review is my LS400. One thing is becoming very clear... the drivers side removal and installation is going to be HARD. At the minimum several parts will have to be removed including the motor mount and possibly the steering shaft and the A/C compressor. This is assuming it can be done at all without pulling the engine. At the wrecking yard the engine was out of the car and one nut would not come off a stud. The guy worked for 20 minutes to finally get off ONE nut/stud.

Next, the driver side manifold wraps around behind the steering shaft and there is no room to go over the top of the shaft. This means the same must be done with a replacement design. It also has the oil dipstick tube between the 1st and 2nd port and the auto trans oil dipstick over the last port. The rearmost port is the worst as there is very little space to route it. In fact on the factory manifold it actuall travels the wrong way and makes more than 90 degree VERY sharp turns. That said the drivers side manifold is definitely the better flowing of the 2 manifolds. It has 2 full length pipes on 2 of the ports and 2 very short pipes entering at 90 degrees.


The passenger side is a different story. Access is MUCH better and may be doable without removing extra parts. It is also the worst of the 2 manifolds with only 1 full length pipe and 3 short runners (2 virtually non existant) that enter logs at 90 degrees. The 3rd and 4th ports are the worst with the 2nd being nearly as bad.


01-31-04, 07:35 PM
WHOAH...

Nobody is claiming 30-40rwhp. It is not impossible but the target for BOTH manifolds is 20rwhp. These may actually improve the torque curve which will be even BETTER than a peak only number BUT... PLEASE understand that we just do NOT know how much power we will get until we get it

02-02-04, 09:44 AM
A friend of mine just bought a 2003 LS430 and that gave me a chance to give it a close inspection. It looks as though Lexus changed the manifolding for the 430 cars and these cars now share one part number so any 430 vehicle should represent the others. As it stands now I cannot say whether or not these headers will be a direct bolt in for the newer cars. The 430 vehicles have 3 catalysts and the ones bolted to the manifolds are definitely different. I will try to update soon but this project has gotten complicated.

02-05-04, 03:03 PM
Yes, this project is going forward. There are just a few people with 430s that are in on the GB with the majority of people having a 98-00 GS400 (and in at least 2 cases a 98-00 LS400

Let me take a moment and try to shed some light on the complexity of my original design goal. The plan has ALWAYS been to build headers for the GS400 and of COURSE the 98-00 LS400 This was the result of me PERSONALLY wanting headers for my car. Now, correctly assuming that the head flange would be the same on ALL Lexus V8 cars from 1990-2004 it was a fair guess that these (with minor tweaks) would bolt up to all of these cars. The BIG spoiler has been the steering column. On the LS400 it requires the drivers side to snake around it VERY closely. This is one of the main reasons for the difficulty of installation. Just removing the stock drivers side manifold is very HARD.

Next, the 1990-97 LS400 and the 1992-1997 SC400 really REALLY need manifold HELP

So, the plan was if these bolt on the head (they will) then all you need to do is relocate the cats and you are set. PROBLEM. Since the manifolds must be built very carefully to fit the primary vehicles we will NOT know if they will interfere with the SC steering column (or other parts) until a set is physically built and test fit. This is not a job for a beginner. We may get lucky and they will bolt right in. If so, full steam ahead. If not there is a chance we could rework them to fit if there is enough committed interest. As of now there are not 20 SC400 participants.

So, for GS400 and 98-00 LS and SC400s we will go ahead with the passenger side and based on the interest level... we will probably build the drivers side a month or so later. (depending on prepayments). Once the passenger side is built I will probably request on of the 1990-1997 400 owners (maybe both an LS and SC owner) to trial fit one on their car. If it fits then we can get a very good idea about the drivers side. There is an Phoenix based 92 SC400 that I will ask to go by the shop for measurements.

There is todays update. Please, everyone stay relaxed. We shall do our best to make this work one way or another.

02-07-04, 05:53 PM
Actually, one of the hardest parts of the installation on the post 98 cars is the removal of the drivers side manifold. This is not the case with earlier cars as several people have removed their manifolds and installed the Tex headers... so... we know that on 92-97 SC400s that the manifolds can be removed without pulling the engine. We do NOT know this about the 98 and later cars. Actual installation is a unknown and will be until we actually have prototypes to test fit.

As far as cat relocation... yes... welding will be required. This is something any exhaust shop can do but of course the quality varies. The best bet will be to relocate the cats under the car and bend pipe from the headers to the cats and then from the cats to the exhaust. Cost depends on individual choices, materials and designs.

02-09-04, 08:25 AM
Mustafa, I have actually contemplated MANY different approaches to solving the exhaust problem on ALL of these cars. At this point all I can do is ask everyone to wait while we solve some of the prototype problems and then we should have a clearer idea on the best approach to take.

Jay, yes, it is reasonable to assume that you can make stock 98+ power with exhaust mods on your 92 and at only 69k your car is still... "new"

02-20-04, 09:11 AM
Wow... I usually check this thread once a day but was gone for a few and now I see there are some issues to address.

First of all. This project began because I wanted headers for my car. I located the builder after finding his work on the Tundra V8 and thought we could save some R&D time since he knew the basic engine. To build a single set he would need MUCH more money and need my car for R&D. These were not reasonable options for me. He told me the Tundra project happened because a member of that forum collected enough committed purchasers. BTW, that project has been delayed while trying to get proper harness connectors to extend the 02 sensors. One of the issues with long tube designs. R&D is rarely straight forward as what we envision in our minds must then be built in a produceable way. This is MUCH more involved than most can realize from many engineering aspects.

Ok, remember that I am NOT the manufacturer or a speed shop or anything else. I am not profiting from this project and can only make the effort I have and will continue to make to get something good built. The fabricator has not made a penny on this project and is ONLY considering it because we have grouped together and promised to buy something he builds. He may never make a meaningful profit for this effort and I certainly will not. While I do understand and simpathize with those who are eager to see these hit the market all I can say is I am trying.

Now, the original HOPE was to build a universal design that could be adapted to all Lexus V8 cars. These manifolds are RARE to find off an engine or even without heat shielding so it is HARD to design, measure, calculate and predict all the variable WITHOUT having parts to touch and work with. jmecbr900 stated that I requested money help on this forum. Actually I did not. I sent all that had emailed as committed an email and told them the need for stock manifolds and the only options I could find. A handful did contribute and I was able to locate and buy a set off a 99 GS400. A few people brought the discussion to this thread but I never asked anyone through CL for anything.

Design wise, for me, it was important to keep the stock cats in their stock location. Building a header to fit the 98+ engines meant that the earlier cars would not have that option and would need to relocate their cats under the car. This was all anticipated and well discussed with everyone that committed. What is still unknown is if there will be any interference with the part we end up building and all the potential models that it could fit. A couple of people are interested in Australia and those cars have the steering wheel on the right hand side of the car. I don't know if it is appreciated how tricky it is to do what I am trying to get done. The ONLY way to proceed is to prioritize. Since the GS400 is BY FAR the largest part of the committed group that is the engine of first priority. I will do my VERY best to get a design built that also fits pre 98 SC400s and LS400s. We MUST first get the part built and then TEST fit it on the target car.

A HUGE problem surfaced for the 98 and newer cars in that removal of the driver side manifold is VERY hard possibly requiring engine removal. The decision was made to start with just the passenger side manifold. (details are in this thread already so please read to learn more about this). On 98+ cars just replacing the passenger side manifold will allow a better than 50% solution. It makes perfect sense to fix what can be fixed. To build a drivers side manifold requires more work and the builder would require prepayment. Several people have committed to prepayment but before I am going to even open that up I want to get the single manifold built and tested. Once that is done we can decide on the next step.

In addition to all of this I am extremely busy with personal commitments. I actually feel guilty working on car stuff with these other demands. Nevertheless it is proceeding and I will keep everyone up to date.

Questions and complaints: Everyone that signed up as committed to buy these manifolds are in my personal email list and have been receiving updates. If this describes you and you want to ask me a question or have a complaint please respond to one of those emails. As some haveprobably noticed my PM box has been maxed out more than once from this project and CL is a painfully slow system to use on dial up (yup still slow here). Answering PMs requires several minute each time. I am not trying to discourage people from writing me but please understand this is NOT a business. I will do my best to answer all questions and post updates in this thread. If you haven't committed and still feel it necessary to complain in this thread... that is your choice. As I have said before if anyone can do a better job you have my blessing. I for one would love to be able to just buy a set of manifolds and be done with it.

I am not bitter and understand that there are a lot of people that at least claim to want these parts. Hang in there folks... If you cannot... or just want to wait and see... please be patient.

JBrady

02-26-04, 07:56 AM
Hmmm... this is odd. Did it give the procedure? If the engine must be pulled then this suggests about 3 hours removal and 3 hours installation. That seems optimistic. This would also mean that total time would be about 7 hours to do both by pulling the engine. On my LS400 the passenger side "looks" accessable but I haven't tried to pull it yet. I will wait to have the passenger side manifold to try. If this is the case then passenger side should take only a couple hours. I guess we will have to see.

Project update. I had the manifolds for longer than expected doing measurements and planning. They were shipped last week and as of yesterday had not arrived. That is expected today. He will then begin measuring and jigging. From there construction of a prototype can begin. I will update with news so if you don't see anything reported there is nothing to report. I would say this means we are at least one month out with no guarantees. I know there are many on here that are very eager but we are making something brand new that nobody else (except Toyota) has made with production in mind. Lots of minor but tricky things to consider. Hang in there and hopefully we will all have faster cars very soon.

02-27-04, 09:00 AM
Jay, your car is different. The pre-98 SC400s have the earlier style manifold that has been removed by many. The question applies to the post 98 cars. With that in mind I cannot see how it could take 13 hours as the engine could be pulled and installed in much less time. If in fact it has been suggested that the factory proceedure (not necessarily the only way or even the quickest way) requires engine removal. As I stated it "looks" like the passenger side definitely does not require this on my LS400. Each side is very different and an equal time seems odd unless Lexus quotes 3 hours to remove and 3 hours to install the engine. That would leave 1/2 hour to change manifolds. 6.5 hours TOTAL for both. Again, this is in no way comfirmed and in fact I expect the passenger side to take about 3 hours on my car. We will know more as soon as we have parts to try.

09-01-04, 11:23 PM
The Tundra headers apparently share the same exhaust port bolt pattern on the head but the rest does not come close to fitting. You could possibly have a craftsman cut them appart and rebuild them to fit but then again it may make more sense to just have a set made from scratch.

Fisher, Jet Hot and other ceramic coatings are good for exhaust as they tend to insulate and therefore keep the heat in the pipes rather than heating your underhood area. On mild steel they prevent rust and corrosion. This is of course assuming that the ceramic are bonded properly to the steel. With stainless parts the benefits are relatively minor due to the lower heat radiation of the stainless itself. See www.burnsstainless.com for more on stainless properties.

11-15-04, 11:45 AM
FINALLY... Just heard from the fabricator. He is finally ready to begin work. He is going to build basic jigs from the GS400 manifolds to locate the head and catalyst flanges. He will then build a manifold for each side that will fit roughtly within the confines of the stock heat shielding. Once these parts are built we will find a car to test fit them on. If all goes well production can then begin.

I have contacted a member in the Phoenix area to see if he can bring his GS400 to the shop for some basic measuring. If there is any other GS400 owners in the Phoenix area please PM me. Now, all told it is hard to say how long all this will take but this project is FINALLY starting.

12-24-04, 08:32 AM
Guys, I know it has been a LONG time... I have said before and will say it again if someone else can get this done elsewhere you certainly have my blessing. From the beginning I just wanted to create a part that will help me and help others. No hard feelings here... just keeping it up front.

I did speak with the guy last week and he does have some work on the jigs started. Shop will be closed until after the 1st and he says he will start again then. I asked him to send progress pictures... jigs... flanges... anything... he said he would try to do exactly that.

So, unless someone else can get a set going I guess we are at this guys scheduling mercy.

01-26-05, 08:28 AM
Well, this was certainly NOT intended as some kind of rumor. The problem is that the fabricator (a well established header building shop) told me that he would build these if I could get 20 or more commited buyers. I did so and then with the help of some of these buyers located, purchased, measured, photographed and shipped a set of stock manifolds to the builder. This was no easy task, try to locate a set yourself if you don't believe me. This was done nearly a year ago on Feb 20 2004. Between employee sickness and scheduling problems and for whatever other reason the fab guy has not built the headers. He says he started the jigs in December.

At this point (as before) we can either wait for him to build these or find another option. I do not have the time or reasources to build them myself or to pull my car off the street and use it to build on or have built.

I understand the frustration however I must request that you NOT lump my name in with the term "internet rumor". Any concern that I have not answered already is welcome. Post it or PM me and I will, as always, respond.

At this point I am going to give the guy another month and then I will go ahead and post his name, shop and phone number so that people can contact him directly. This may or may not help but honestly I am weary of taking the focus for a project that has obviously dragged on much longer than it was hoped for and that is beyond my control.

03-08-05, 09:19 PM
NEWS....

I had 2 conversations with the craftsman today. In the first conversation, this morning, he told me that time was a problem and he was both short on labor force and long on projects. I told him I am would go ahead and build something and see if it can be duplicated. Not an easy task. I asked if he could send me the manifolds and jigs. He said OK...

Well... this evening he called me with the news that he has built a prototype driver side manifold. It is just tack welded at this point and doesn't have the catalyst flange or O2 sensor bung BUT it DOES fit inside the stock heatsheild!!! This is not needed and a surprise. There are some changes that we then discussed but he is shipping me the part tomorrow and I will post pictures as soon as I get it. I will then make some measurements, send it back and he will make the changes as well as start on the drivers side.

After ALL THIS TIME there is actually official PROGRESS

Stay tuned, things just got interesting. Expect the pictures within a week (UPS from AZ to TX is 2-3 days)

03-10-05, 08:00 AM
Since this project has actually produced some results it may be time for an update as over the past year a couple of things have changed from the original post.

First off, due to the choice for prototype building it looks like both drivers and passenger side manifolds will be built and sold as a set. Original quoted price was $400 un-coated mild steel or $600 ceramic coated mild steel. Some applications may want to modify the manifold so ordering uncoated may be better for them. Otherwise I would recommend the coated headers. The $200 premium is very reasonable as $100 per manifold is very fair.

Design, the prototype passenger side manifold fits inside the stock heat shield. The drivers side may not. Pre 1998 and post 2000 shields are different and definitely will not fit either side. Due to this the design of the manifolds is dictated by the available space and location of the catalysts. They will NOT look like the pictures at the beginning of this thread. The idea is to build a manifold that retains as much of the exhaust energy as possible and directs it downstream within the confines of the available space. This is something the stock manifolds do not do well so this should dramatically improve exhaust flow and should yeild the target 20rwhp gain when used with good flowing parts after the catalysts. Please do NOT consider this power target as a guarantee. Final results could be higher or lower and will vary from vehicle to vehicle.

Primary vehicle fitment is for the 1998-2000 GS400. For these cars these headers should fit in the stock location and work with the stock catalysts. Final fitment of heatsheilds should not be expected but may be possible at least on the passenger side. This means the stock Y pipe and the rest of the stock exhaust could be used although not recommended for best performance.

Alternate bolt in fitment should apply to the 1998-2000 LS400 and 1998-2000 SC400. The above statements about the GS400 should also apply.

Possible direct bolt on (except for EGR, see below paragraphs) may apply to the 1995-1997 LS400 and possibly the 1996-1997 SC400. I learned this after I gained access to some factory documents that indicate the twin tube style manifold actually originally came on the 1995 260hp/270tq LS400. Catalyst outlet flange, O2 sensor location and total dimensions are not confirmed. EGR would need to be added. This same rating applied to the 1996 SC400 but I do not have access to drawings for this year SC400 manifolds. The 1995 SC400 had the previous 250hp/260tq rated engine and those had the single tube manifold.

Installation with modifications should work on the 1990-1994 LS400 and the 1992-1995 SC400. At the very least installation will require moving the stock catalysts and using a different Y pipe. No EGR provisions will be made so the installer will need to consider this if they choose to retain EGR. 1996-1997 SC400s may or may not have this same requirement.

2001+ GS430s, LS430s and SC430s are unknown. What is known is that Lexus went back to a single tube manifold to heat the catalysts faster. This style is presumed to be more restrictive than the dual tube design and is a good reason that power ratings did not go up with the larger engine vs the 400s. The 430s also run 3 catalysts; 2 bolt to the manifolds and one is welded to the stock Y pipe after the Y intersection. Catalysts flange size, bolt pattern and angle are unknown and therefore 430 owners should expect to definitely fabricate new exhaust after the first 2 cats and possibly need a transition from the headers to the cat inlets.

That is all for now but I will post more as this project proceeds.

Stay tuned.

03-10-05, 12:29 PM
Mild steel. With ceramic coating the mild steel should last indefinitely and have good properties. Stainless would raise the price hundreds.

Thickness is .065

I should have the prototype passenger header within days. I will post pics then.

JBrady

03-15-05, 04:11 PM
Show Time! First of all lets review the stock passenger side manifold.

Look at the HORRIBLE 90 degree intersection the both of the back 2 ports dump into. There is virtually no runner length and the construction is appaling in that the runners overlap the downstream pipe leaving a sharp inside edge on top of the 90 degree turn and no runner length. The front tube is the only one on this manifold that has any use. The second from the front enters the front tube again at 90 degrees and with the same internal sharp edge. Score, 3 bad ports and one decent port.


Now, look at the prototype.

Each runner exits smoothly and directs the exhaust energy towards the catalyst inlet. Notice how the front 2 runners join in a nice merge collector, same happens with the rear 2 runners. This manifold will flow much better at ALL RPMs.


(Passenger Side) Shown with the heat shield on the prototype.



03-16-05, 11:47 AM
Hollywood, yes, I agree that the stock Lexus manifolds are poor at best. The intake on the 1998+ is actually VERY nice utilizing a two stage runner length and very nice angles and volumes. How anyone who has looked at these manifolds state that they are even average is beyond me. A basic cast iron manifold would be better.

03-16-05, 11:50 AM
No pics because it hasnt been built yet.

I will be sending this back to be completed for pre-production. If the fabricator will go ahead and build the driver side pre production part we should hope to have these available in 30-60 days.

03-23-05, 11:04 PM
#1 - hard to say, depends on what you do about EGR, cats, the rest of the exhaust, who does the work, on jackstands or in a shop with a lift, air tools and professional mechanics. My guess is a minimum 4 hours and it goes from there.

#2 - all 1UZFE engines (Lexus V8) from 1990-1997 had EGR. These manifolds will not have the small 2 bolt flange that the EGR connects to. It is fairly straighforward to weld on a flange and route the EGR. Some simply block it off. There are many posts regarding this if you do a search.

Here is a picture of the SC400 manifold with the EGR flange showing between the back port and the catalyst flange.



03-24-05, 07:14 AM
Originally Posted by Dx3
Since yours is a 95 SC400, rated at 250hp/260tq, I am assuming (yes I understand the risk in doing so) that is shares exhaust manifolds with the 1992-1994 SC400s. In this case you should not have to pull the engine. Actually, I anticipate that the engine will not have to be pulled for any year or model, just unbolted and lifted slightly for clearance. The problem is with the newer twin tube manifolds for 1995-2000 LS400s and 1998-2000 SC400s (with 1996-1997 SC400s being an unknown at the moment) there is no room to remove the heat shields and these shields prevent access to the head studs/nuts. Since multiple people have successfully replaced the earlier cars manifolds with headers WITHOUT pulling the engine we know that is not a problem with early cars.

Ironically, the 2001+ 430 engines went back to a single tube design (which holds back power but heats the cats faster) and for these cars install may be easier than the 1995-2000 cars (excluding the 85 SC400). On the 430 cars a new downpipe/Y-pipe/catalyst assembly will need to be fabricated.

Here is another picture of the prototype to compare to the 1992-1995 SC400 passenger side exhaust manifold (with EGR) shown above. Notice the outlet location is farther away from the engine and the dramatic improvement in design.



03-24-05, 07:38 PM
No, the fabricator is not going to build this part... at least not at this time. Best bet is to find a good muffler shop or speed shop that builds exhaust systems. Now, if you want to remove yours and ship it out for prototype work I may be able to assist in building a part.

The reason this applies for 430 cars is that Lexus changed manifolds and that changes mounting location for the catalysts. They also went to a 3 catalyst Y pipe, 2 at the manifold outlets and one as the 2 side join into one. It would be VERY easy for a shop to simply build you an off road Y pipe without cats. You could add cats to this system for about $125 each. I would personally not cut up the stock system for parts but that is also an option.

03-24-05, 07:43 PM
This is very good news and should mean installation on 430 cars is a fairly easy task.

03-29-05, 09:58 AM
The coating IS JET HOT! They come by the shop twice a week.

Noise will be mostly a function of what you do with the rest of the exhaust. These are shorty style headers which are similar to the stockers in total area. Wall thickness is .065" plus the Jet Hot ceramic coating.

Don't worry about Anthracite. Although I appreciate your support I would also like to have doubters become believers. If he wants a set he can purchase a set, no problem, no hard feelings.

03-29-05, 10:03 AM
While it is impossible to say for certain without test fitting, my guess is that these should bolt on and work for you. Did Toyota change something preventing the use of the current aftermarket headers?

04-02-05, 08:04 PM
These will bolt to the engine. Your 430 has 3 catalysts and they are part of your Y pipe. I do not expect your Y pipe/catalysts to work with these headers. It is remotely possible and will need to be actually checked on a car. All 430 cars (GS, LS, SC) will probably need to build a new Y pipe.

Many have PM'd me asking what the ceramic coating is actually for. It protects the steel making the manifolds last a very long time. It reduces heat loss which increases velocity, performance and reduces underhood heat. It also makes the pipes quieter.

Noise wise these manifolds should be unnoticable at idle, light throttle and cruise (assuming stock exhaust). They will probably be slightly louder at full throttle.

CARB stands for California Air Resources Board and is the ruling party for emissions testing. Technically ALL engine parts that deviate from OEM must be CARB approved or they are illegal for installation on polution controlled cars in California. Since CARB is the strictest in the country any part that has a CARB E.O. number (Exemtion Order) can be legally installed on the specific application for which the E.O. was granted. Now, if the part goes unnoticed by the emission testing technician... you can get away with it. That is why Future is happy that the heat shields (1998-2000 only) fit on the passenger side and probably the drivers side. Now, in order to actually run the heat shields the headers will need bolt brackets for the shields. At this point we haven't crossed that bridge. Stay posted.

04-04-05, 08:38 AM
Thermal wrap would keep underhood temps lower and effectively replace the heat shields. That said thermal wrapping the pipes concentrates a tremendous amount of heat on the metal. It can also hold moisture when the vehicle is not running. Personally I will not be wrapping my exhaust.

REGARDING the heat shields. Yes, the passenger side shield fits BUT at this point no provision has been made for mounting brackets. The shields are attached to the stock manifolds by metal bracket welded to the stock headers. If you look at the stock manifold you can see 3 brackets, one on the 2nd pipe, one near the o2 sensor and one on the back pipe. In order to affix the heat shield we would need to design and locate and build these brackets. This is not an easy task and would increase the cost of the manifolds.

At this point I haven't even discussed this option with the fabricator. Honestly, I am more interested in getting manifolds built than any heat shield issues. The reason he made the header to fit inside the shield was to assure fitment in the vehicle. So, at this point do not expect to be able to use the heat shields. This may become an additional cost option but do not plan on it.

JBrady

04-05-05, 06:48 PM
The stock ECU/MAF/injectors/fuel system should have no problem with up to 25% more air mass flow. Mo at SRT suggested (over a year ago on a phone call) that the stock system should support nearly 400hp at the crankshaft. These headers and any supporting exhaust should not have a problem with either a stock or an SRT equiped engine.

Regarding underhood heat... I don't see a problem. If you have sensitive components that are close to the exhaust they generally have some kind of insulation from the factory, either a shield or wrap. Of course you can always use header wrap to spot insulate any actual components that worry you.


Originally Posted by RRocket
More info on coatings...
I have used ceramic coatings extensively in automotive and other powersports. On headers, a reduction in heat can exceed 200 degrees from using a ceramic coating. The coated headers also produced more power. Although I've never used Jet-Hot, I'm sure the results would be similar. Heat shields aren't usually required. The ceramic lowers the temp that dramatically. Forget about wraps too. They are fine and good for racing applications where the headers can be replaced often. The excess heat from wraps can cause the headers to degrade over time. Ceramic has no such issues. And it also aids in scavenging. Less heat, more flow, more HP and a nice chrome like finish. It's well worth the additional expense.

04-06-05, 12:33 PM
The only ones that should order non-coated headers are those planning on modifying the headers during installation. This would only apply to 1990-1994 LS400s and 1992-1995 SC400s. There is still an unknown for 1995-1997 LS400s and 1996-1997 SC400s. ALL others should go coated.

That said, we may end up with an application specific header set for the earlier cars but for now the VAST majority of commited participants have 1998-2000 GS400s, 1998-2000 SC400s and of course 1998-2000 LS400s and these are bolt in applications.

04-07-05, 04:18 PM
My best guess on 1995-2000 year cars will be the engine will need to be supported and the engine mounts removed. I do not expect to remove the engine. The hardest part is removing the stock heat shields. That is why the trouble. On earlier and later cars this should not be problem. Install time I am GUESStimating at 6+ hours. Should be doable by a competent mechanic on jackstands. Obviously the better equiped the shop the easier the install.

04-16-05, 10:41 AM
I just sent an email update to all commited people. Anyone that didnt recieve it either is not on the list or there is a problem with their email. The fabricator has now built the drivers side prototype. I should have more information next week and hopefully pictures.
This is getting very close!

04-16-05, 09:44 PM
Here is the stock drivers side manifold. No pictures of the prototype but this is a reminder. Ports 1 and 2 are ok but ports 3 and 4 are terrible. All in all the stock manifolds make for 3 decent ports/runners and 5 bad pipes. The shorty upgrades will give all 8 cylinders breathing room!
At this point I can't comment on subsequent production but I am sure if the demand is good enough (20 or more for second run) he will make them.



angle 2



Here is a close up of ports 3 and 4. Notice that 3 is 90 degrees and virtually no length. 4 is actually worse as it points in the WRONG direction.



Here is a reminder on construction. The short runners, all 5 of them, have this same construction. The primary pipe fits OVER the secondary pipe and there is a sharp lip inside the runner... this is TERRIBLE for flow. Remember, these are the 1998-2000 manifolds which are the BEST of all the years. The 1990-1997 and the 2001+ manifolds are WORSE.



04-17-05, 08:26 AM
[IMG]Originally Posted by verylost
I know you are close to the completion of the prototype phase, but people need to realize that once the prototypes are made, it will still take time for subsequent headers to be made.

I am going to assume that each header is going to be hand crafted. I highly doubt you are going to go into mass production with molds etc. Hand building these things takes time. I know it won't take another year for the headers to be made, but the initial demand so far may result in at least a month (possibly 3) wait for some before receiving the final product.

I don't want to rain on your parade, but I wanted to inject some reality into this thread.

jbrady, you have my sympathies for going through with this project. There have been a lot of negative detractors who simply don't understand the design and production process of such a project. Congratulations on a job well done.[/IMG]
Well, while there is some truth to your point it is also true that the fabricator is actually a production header facility. They mandrell bend pipe on a production basis. They will make jigs from the prototypes and bend all the pipes necessary. Each part will be finished and then the entire header will be assembled. This is a production process and is not just one individual building headers from scratch one by one. So, yes, they will not be made all in one day but they will not take that long once productiion is ready.

04-25-05, 07:55 PM
NEWS... Prototype of the drivers side is done!



05-18-05, 12:33 PM
Basically a one off custom design takes time that is just not available right now. Lexus redesigned the manifolds for the 430 engines. It is POSSIBLE that the manifold flanges (head and catalyst) are in the same location. The bolt pattern on the head is the same. IF (BIG IF) the flanges are in the same location as the 2000 1UZFE... then the new headers would be a direct bolt in. I am not making this assumption. The only way to know is either test fit in a GS430 or have someone send in some GS430 manifolds to see if they will bolt into the header jigs.

For now, I am going under the presumption that they will NOT bolt in. This will require a custom Y pipe. This can be made from the stock Y pipe or contructed new. $500 will cover one without cats and make these a bolt in. With cats will cost more depending on your cat choice. Nice flowing metal substrate cats are available for under $150 each. Modifying the stock catalyst Y pipe would be easiest but will make returning to stock configuration (if ever desired) more expensive.

These are options I am not worrying about until the headers are actually built. Then we can find out for certain.

05-18-05, 03:30 PM
1. no
2. yes
3. always a good choice but not required

05-20-05, 10:49 AM
Although I cannot guarantee it I believe all the 430 cars, SC430, GS430, LS430 all share the same exhaust manifold. Lexus went back to a more restrictive single tube design on these engines and increased the displacement which would further compound the restriction. This is one of the main reasons that the 430 engines did not recieve an increase power rating.

IMO headers will respond better on a 430 engine than the 400 engine as there is more restriction to release on the bigger engine with the more restrictive factory manifold.

Now, since we have not built and installed the headers yet we can only speculate but lets use a GUESSTIMATE of 20rwhp gain for a GS400, logically, we could then GUESSTIMATE the 430 gains at 25-30rwhp with no other differences. This would assume that the rest of the exhaust is not restricting the headers flow.

05-21-05, 11:04 AM
It is true we will not know the power gain until these headers are installed and tested. However it is interesting to note that the difference between the 290hp/300tq rating of my LS400 and the 300hp/310tq rating of the GS400 is mostly in the 0.39" in the single center exhaust pipe diameter (1.97" vs 2.36").

For me, it is difficult knowing that there is "free" horsepower trapped in this engine. Free in that the engine will happily make it if we only remove limiting factors such as lousy manifolding. The intake manifold is a beautiful work of art. The only explanation for the exhaust manifolding is that Lexus wanted to restrict the output of the engine coupled with manufacturing limitations and emissions regulations. MOST other performance oriented engines from the factory have decent exhaust manifolding. If this was the case with our engine I would not be making this effort.

Personally, I will be surprised if the gain is less than 20rwhp. I would be pleased but not shocked to see 30rwhp.

An example would be a Ford 5.0 I built years ago. Rated at 225hp they typically make 180-190rwhp. With 1.5" shorty headers replacing the stock crimped headers and mild porting of the stock heads (still less flow than the 1UZFE) my engine dyno'd at 249rwhp and 314rwtq. This is a gain of 60-70rwhp. Significant was that peak power with stock valvesprings was at a very low 4600rpm. As RPM goes up, if torque does not drop off, power goes up. Our engines at 6000rpm have a greater need for efficient exhaust than my example. Now, I am NOT suggesting a 60hp gain. But there are more than a few engines making over 100hp/liter with a similar layout to the 1UZFE. This would require more RPMs and more valve flow but without decent exhaust manifolding you can forget it. BTW the porting I did on the Ford heads above did NOT increase the size of the intake port at the intake manifold and barely increased the exhaust size. Instead of making bigger ports I made them flow more. Same idea here.

All this is speculation. Time will tell.

As far as additional runs of headers after the first... I can't say. The builder must run batches of 20 at least to make economic sense. Will more be available later? Depends on the demand.

Would you feel 20rwhp? Absolutely. I would compare it to the difference between how our engines run in cool crisp air vs. hot humid air. You know how sometimes these things FEEL so strong and other times we are dissapointed? That would be around 20rwhp. Now, of course these engines will still have a range dependent on environment but it will be moved UP so that the low range will be our current TOP range.

05-23-05, 02:12 PM
I can't make any absolute "exact" statements before the parts are actually built. My best educated "guess" is that you will need to fabricate a Y pipe with or without cats to connect to the header outlets and center cat back exhaust. Your stock heat shields will not fit. In fact no provisions are being made for any heat shields to fit. The fact that these fit inside the 1998-2000 heat shields is a fitment and clearance concern only.

It is POSSIBLE that Lexus did not change the flange mounting locations between the 400 and 430 engines. They may have just changed the manifold layout only but kept the head to catalyst dimensions. If so, these would bolt right in. I am going on the presumtion that this will not work (although it may). Provisions for the O2 sensors will be made in the headers.

Any Y pipe will need to make provisions 02 accordingly. Some may opt to cut the catalysts and flanges from the stock Y pipe and use these parts to construct a higher flow Y pipe that will fit. Some may wish to keep their stock (expensive) Y pipe and fabricate a new one with or without cats.

05-24-05, 04:46 PM
I confirmed that each RUN of headers requires a minimum of 20 sets. Will there be a second run? Hard to say. Time and demand will tell. I would suggest that these will be a limited production part and that anyone that buys a set will probably have no problem selling the set if needed for nearly the purchase price (or possibly higher depending on results and future availability). Even if you sell at a loss we are talking very minimum risk here.

As far as a custom Y pipe for 430 cars.

Option 1: Good cats can be had for $125 each. A good Y junction for $100. Flanges are tougher but would cost about $100 for the 3. Tubing and labor to connect the parts shouldn't run over $200. Cost for custom Y pipe with cats and flanges, about $800.

Option 2: Same as option 1 but without cats, about $400.

Option 3: Modify existing Y pipe to fit. Probably around $200.

Option 4: Cut flanges and cats from stock pipe and add 2.25" pipe and quality Y intersection, apx $300.

It would be nice to offer a bolt in Y pipe for these cars. It would probably require a different one for the GS430, LS430 and SC430. In order to do this someone would need to use their car as their car to pattern a system and then reproduce the part for sale. Again would be nice but I don't have a GS430 to offer.

05-24-05, 09:45 PM
Regarding 20rwhp being worth the trouble. I guess that depends on each individuals personality. Another way to look at it would be, lets imagine the factory built the GS400 with headers like the ones we are planning. Lets further imagine that the engine was rated 325hp instead of 300hp (about 20rwhp difference) and the car was 3 tenths of a second quicker 0-60 and in the 1/4 mile. Lets consider that JUST before the cars where sold Lexus decided to place restrictors in the exhaust to reduce power by 25hp... for "insurance" reasons.... How many of us would PAY to remove those restrictors? Do I see a whole bunch of raised hands?

Well, imagine no more because that is ALMOST what Lexus did. Look at the manifolds on almost ANY other performance engined car and you will see MUCH better manifolds. Lexus must have wanted to restrict this engine. Heck, 6350rpm redline is NOTHING for a small displacement oversquare 4 liter engine with 6 bolt mains and a forged crank. The undersquare GM LS6 makes 405hp at 6000rpm with 10.5 compression. Our 1UZFE and 3UZFEs can easily run 7000rpm. Our valve lift is a paltry 0.300" and duration is nil. A little more cam, good exhaust and 7000rpm would make 400hp a realistic potential. Our intake manifolds are GREAT. Lexus may indeed have found these engines TOO powerful and actually detuned them with among other things LOUSY exhaust manifolds.

BTW, the GM LS6 I mention above is a 2 valve/cyl head, single cam, push rod design that makes 96% as much power per liter at the same RPM and compression ratio as our high tech 4 valve/cyl, dual overhead cam engines. The LS6 has GOOD factory exhaust manifolds and typically picks up 20-30rwhp with headers. With ported heads, headers and larger cams MANY of these engines are making over 450rwhp (530hp crankshaft using a conservative 15% drivetrain loss) up from a stock 345rwhp.

Oh, and too rub salt in the wound, the 2002-2004 Corvette that this LS6 came in is rated at 19mpg city and 28mpg highway

05-27-05, 08:43 AM
I just recieved a PM regarding whether or not headers would be recommended on a supercharged engine. The answer is YES. Here was my response.

While it is actually very complicated let me give you a simplistic explanation. The supercharger will force more air into the cylinders, this greater air combined with greater fuel will create more energy pushing the pistons down and creating more power. This process creates more exhaust gas that must be removed from the cylinder to allow the process to begin again. The stock manifolds are restricting the stock exhaust flow needs. Obviously adding more exhaust demands will make this even worse. Supercharged engines will respond even better to higher flow exhaust than non-supercharged engines... period.

JBrady

05-28-05, 09:00 PM
I just reviewed the technical pages for the GS430, LS430 and SC430 and it LOOKS like Lexus used the SAME Y pipe, cats and headers on all three vehicles. This is good news. The Y pipe does not have the front 2 cats attached only the 3rd. This makes a 430 Y pipe very reasonable. Maybe a non catalyst Y pipe with room to add a catalysts for those wanting one. Options create additional R&D time and expense. If one pipe can be made and sold that would be ideal. It would be very good to test fit a GS430 Y pipe on a GS400. If it fits that increases the chance that the headers will be a bolt on. The flange style is the same but exact bolt location, spacing and angles will not be known without test fitting.

05-29-05, 07:44 PM
Correction: The GS430 and SC430 appear to have the exact same Y pipe. The LS430 is very similar with a slight difference where it joins the muffler section.

GS430 Y pipe section diagram:



GS430 muffler section diagram:


05-30-05, 12:28 AM
Yes, same place as 1998-2000 400s. Here is the diagram showing the drivers side manifold. The passenger side is shown but the layout is not apparent. It is the same for both sides. 2 decent runners per side. Remember, this is a bigger engine. The manifold to catalyst location does look just like the earlier design. Who knows, we may get lucky.



05-31-05, 12:37 PM
To summarize: at this point I do NOT know if the GS430 exhaust manifolds locate the header to catalyst 3 bolt flange in the same location (position, orientation, bolt pattern, spacing) as the 400 manifolds. IF and this is a HUGE "IF" we are very lucky... Lexus kept the location exactly the same and the catalysts outlet flanges as well. If all this were to occur we could interchange GS400 and GS430 exhaust systems. DO NOT COUNT ON THIS. It is possible.

HOPEFULLY, the 430 catalysts will bolt to the headers. If so, this only leaves the 3rd catalyst to replace. I am not certain the car even needs the 3rd cat to pass tailpipe emissions sniffer tests but it would be required by a visual inspection.

IF it is necessary to create a new Y pipe I would suggest a careful cut to remove the 3rd cat from the stock pipe and allow it to be welded to a higher flow Y pipe would make the most sense. This process could be reversed fairly easily if needed in the future.

NOW, lets talk a little about the GS400 Y pipe. I have scheduled with another CL member to do some testing with his 1998 GS400 Y pipe this comming weekend. I may decide to build a replacement Y pipe for GS400 owners. This pipe would be recommended with the headers (or another high flow Y) and it could actually be used by GS400 owners even it they did not install headers. Stock size is dual 50mm (1.97") OD pipes feeding a single 60mm (2.36") OD center pipe. The upgraded size would be dual 2.25" (57mm) pipes feeding a single 2.50" (64mm)center pipe (with possibly 2.75" and 3.00" options). At this point please do not expect or plan to purchase this pipe through me but it may become a viable option. I should know more after next weekend. IF the above info on the 430 cars holds true , if produced, this pipe could be used on the GS430s... again, a bunch of IFs...

Unfortunately the only thing we can count on with the 430s is that the header will bolt up to the engine and fit in the engine compartment. 400s can use there stock cats, Y pipe and mufflers although upgrading the Y pipe is recommended. A single 50mm pipe is not much to carry 160hp (320hp /2 = 160hp that each pipe carries)

06-06-05, 11:14 PM
Well, the GS400 and LS400 Y pipes are NOT compatible. The catalyst downpipe angle is SLIGHTLY different. As TXGS mentioned we did not get the chance to check the GS430 against the GS400. Maybe we will get another chance.

Here is a picture of the LS400 Y pipe sitting on top of the GS400. They are so similar you have to look very closely to see that there are in fact 2 in the picture. The angles around the transmission are identical. It is the angle of the cat flanges that is slightly different and of course the length of the center section.



06-07-05, 01:18 PM
Actually all of these cars SHOULD run a higher capacity Y pipe to get the most effect from upgrading the headers. That said, the GS400s will NOT need a custom Y pipe to actually fit and function. It is just better if they do. It would have been nice if the mounting of the LS400 and GS400 were the same as then one custom pipe could have been produced for both cars.

To confirm on the GS430 vs. the GS400 I will want to test fit the 400 Y pipe to the 430. If that fits I want to test fit the 400 cats and Y pipe on the 430. That will confirm fitment. However, all of these cars need a Y pipe upgrade. Anyone wanting these headers should plan to at least some point upgrade the Y. If you have a GS430 or other 430, and really want the headers, my recommendation is to buy them now. Wait until another 430 owner who plans on upgrading the Y pipe anyway does so. Once that is done we will know if the stock pipe fits or not. Worse case scenario is you decide it is not what you want and you sell the header to someone who wished they got on the first production run when they had the chance. Truthfully, this is a small risk reward ratio.

06-07-05, 01:52 PM
1. Unknown, expect to at least remove motor mounts. Actually removing the engine is not anticipated. This is for GS400s. Earlier LS400s and SC400s have already replaced headers without removing engine. I also think the 430s will be easier due to their stock manifold design.

2. No heat shields.
3. Most if not all of the headers will be Jet Hot coated.
4. Not at this time.
5. None of the 1998 and newer cars have EGR, non issue.

06-07-05, 01:55 PM
Head removal will NOT be required. Access is the only limitation. Removal of the stock heat shields is the biggest hurdle. Once they are out of the way the rest is not bad. This is for 1998-2000 400 engines. The 430s have a narrower manifold which leaves more access room.

06-07-05, 02:02 PM
On 1998-2000 GS400s you will need headers only. Y pipe recommended. I may be able to offer a Y pipe but I am making no promises. The stock one will work but will be somewhat restrictive. I recommend 2.25" piping on the duals and 2.50 or 3.00 for the center pipe. No complete "kit" is planned.

06-07-05, 11:32 PM
Actually, on the GS400s it is a 60mm/2.37" resonator. Yes, upgrading to a slightly larger center pipe and duals is a good idea. Just keep it below 2.25" on the duals.

06-08-05, 04:09 PM
.
This is definitely news to me. The Lexus diagrams that I have do not list the GS400 or my car for that matter. I have never seen a picture or in person of a 3rd cat on a 1998-2000 model year Lexus V8.

Please post a picture. this must be a California required part and possibly Canada?

I doubt this catalyst is too restrictive. If it were mine I would probaby just cut the cat of the factory pipe and weld it to an upgrade pipe. This is only one weld and would be relatively easy to reverse if needed.

Also, Hameed, I would not recommend a 2.5" X-pipe. The idea is to keep velocity high. The bigger diameter will slow the gases. It will work just not as well. Please post a pic or email it to me.

06-20-05, 11:20 AM
1. Run dual cats with 2.5" inlet/outlet. This is due to the header outlet being 2.37". Extra flanges should be available for those wishing to custom build downpipes.

2. 2.5" will reduce your power in the driving RPM range. It may help SLIGHTLY under NOS but I would suggest your configuration and muffler choice is much more important here. Personally, I would go 2.25". A single 2.25" will support 300hp... dual 2.25s would support 600hp.

3. Run the same size X or Y pipe as the dual pipe size. EXECUTION is everything. A proper (like Burns) X or Y pipe will increase performance in the low and mid range without restricting top end power. There are multiple styles and theories. I prefer the Burns style to the Hedman or Dr.Gas style but either are good choices. Whatever you do make certain the flow path is smooth, unrestricted and the merge angle tight.

4. I am unaware of a better location that the stock location.

06-20-05, 11:14 PM
Actually there is a difference in function between an H-pipe, a "window" X-pipe and a Merge X-pipe and a Y pipe. The H pipe and Window X work very similarly. The idea is NOT to split the flow but instead create a plenum effect, ie, have an area where the pressure AND sound waves expand into. This deadens and reduces the available pressure to travel back up the pipe. In a Merge X pipe and a Y pipe both flow paths are joined to create a common flow. This works in the same way that joining primary pipes in a header improve flow. The total flow is less resistant to reversion and creates a one way flow path. Once the two sides are joined you can split them off again and retain the effect. All of these devices change the tone of the exhaust. Final tone is determined by total volume and resonance of the components.

06-26-05, 08:29 AM
I am talking about the Y intersection. The two feed tubes should join at around a 45 degree angle. You want to maintain the enertia which creates scavenging. Another goal is keeping the volume in the merge collector as small as possible. The tighter the merge angle the larger the volume but the worse for flow. Carefull design is required for an optimum part. Review the Burns stainless site for picture examples.

06-28-05, 08:25 AM
Spoke with the manufacturer yesterday. Passenger side header is welded up and the drivers side should be done today. From there the parts go to Jet Hot. Should ship to me around next Wed. Installation and final fitment confirmation is next. If all fits as intended it is TIME TO ORDER!

07-13-05, 09:32 AM
Price for Jet Hot coated is $600 + sh. I would not suggest uncoated for any application.

It is possible that dyno numbers will be available but MOST people do not understand how to interperet dyno information. There are MANY variables. Remember these are OBDII computer controlled engines that actually LEARN and adapt and tune themselves. Just installing the headers and immediately dynoing could easily give false high or low readings.

The bottom line is ANYONE who understands how engines run can clearly SEE how restrictive the stock parts are. Every single engine ever made responds positively to improved exhaust flow dynamics.

These will bolt up to the GS430, SC430 and LS430. They MAY bolt up to the stock cats and exhaust but there is no way to confirm this without actually trying it. Short of that I can only suggest that 430 owners plan on fabricating/modifying their Y pipe. I am relocating to upstate NY for the summer and fall and may be able to assist in building a GS430 specific Y pipe if a CL member/430 owner can coordinate with me. I will be in Rochester. So, 430 owners can order headers and wait on a possible Y pipe, have a custom Y pipe built, have their stock Y pipe modified or get lucky and have the stock parts fit. I say lucky from an ease standpoint as a better flowing Y pipe will increase performance.

On 1998-2000 GS400s the will be direct replacement parts for the stock manifolds and will work with the stock cats and exhaust pipes although a higher flowing Y pipe is still recommended.

07-14-05, 08:11 AM
The biggest problem with the installation is removing the stock manifolds. The passenger side does not look to be a problem. The drivers side is another story. I do not expect to remove the engine. I do expect to support the engine and remove the motor mounts and other items like the steering rack for access.

We will know much more very soon as the first set of headers is shipping today and will be ariving early next week. Depending on shop time and scheduling they could go in as early as next weekend. Installation will be on a 1999 GS400.

Regarding supercharged or nitrous engines. YES. Headers will deliver more improvement than on a lower output engine. This is because the extra power comes from extra displacement via a compressor or liquid gas. This extra displacement means there is a higher demand on the exhaust system to get rid of the extra exhaust flow. Conversely, without improving the exhaust system your FI application will not deliver the power it should. It will also cause more heat to be transfered to your heads and valves. For me headers (improved system flow) are a requirement when going FI.

JBrady

07-19-05, 08:57 AM




Some pics of the Driver's side

JBrady

07-19-05, 05:50 PM
OK, I have been on the road for 2 days relocating to upstate NY to care for my ailing mother. I haven't had time or energy to focus on this at the moment. I did speak to gawd today and 15 hours seems off especially since Dx3 got a quote for 7. I honestly cannot say. We should know more soon.

As far as these being the worst bang for the buck... well... eye of the beholder. Right now you can get gears, lsd, SRT intake, PI TC and that is about it other than NOS and FI. Headers at a very real need on a performance engine. If you don't think so, fine, but please whine about it somewhere else.

I don't believe gawd has a clogged cat. A slight exhaust leak at between the Y pipes is not going to cause a measurable power change. An 11.5 A/F ratio is. He has the SRT with race ECU and that probably needs tweeking. 230rwhp seems low, 260rwtq seems reasonable.

07-21-05, 02:56 PM
LFL, Hollywood does not appear to be answering with any sort of anger. His answer is almost completely accurate. The only missed point is that I will not be handling the sale at all. The list members will deal directly with the manufacturer.

As far as future runs go. There may well be additional runs. Minimum quantity is 20 sets. Someone will need to do a GP of some sort or the manufacturer may not get enough orders at a time to make the run. He may do single sets at a sizeable price increase, I don't know.

As far as "precision Japanese engineering" the stock manifolds qualify only from the perspective of emissions, noise and durability, definitely NOT performance.

As far as VVTi and the delicate balance, sorry, this is not a good argument. I have studied the VVTi timing charts and can say that backpressure is NOT part of the equation.

Modifying an engine does bring with it pros and cons. Large tube headers and or gutted catalytic converters and large diameter systems can certainly effect power and drivability in a negative way. That is why I specified tight 1.5" primary pipes. These manifolds should be an excellent compromise between maximum peak power and strong low/mid range and drivability. These headers should deliver nearly optimized peak power without compromizing elsewhere (considering the design goal of retaining the stock catalysts in the stock locations). I would be better to have used 304 or 321 stainless steel but the price would have increased nearly double. With the Jet Hot coating these should last much longer than most will own the cars.

On the subject of "marketing". It would be EASY to doctor a dyno sheet to show ANY power gain. Believe it or not many parts are sold this way. Heck Mazda and other manufactures have been caught lying about their engines power (Miata, RX8) How may of the aftermarket parts have independent dyno tests PRIOR to most purchasing the products? The real value is in design. If you design a part properly (like these) you have created the potential for more power from EVERY OTHER mod you do. Exhaust dynamics is not a manufacture specific phenomenon. Anyone that truly understands engines can study the pictures of the stock manifolds that I have posted and KNOW without question that they are reducing power.

For those that wish to wait... fine, wait, it just doesn't matter to me. All I ask is that people refrain from repetitively posting the same complaints. Once is plenty. I challenge anyone to point out a concern that I have not addressed. By continuing to repetitively post some people are (probably unwittingly / ignorantly) showing disrespect and condescension.

As has been stated MANY times, we cannot know the actual results until these have been installed and MULTIPLE dyno runs have been completed. This is due the fact that OBDII engines usually must adapt to changes before the true consistent effect is known. As a consideration the manufacturer was telling me that some of the Honda engines have pretty good exhaust manifolds from the factory and he is only seeing around 10% gain on those engines. Our manifolds are NOT good. A 5% gain on our engines will be about 12rwhp. 10% around 25rwhp. These are peak numbers and often midrange power can increase even more. In fact you could have an engine make ZERO additional peak power but in fact have midrange increases that make the car perform much better. Again, gains here are speculation BUT the stock manifolds are effectively restrictor pipes. If you restricted the stock pipes further would you expect a gain or a loss? (easy question yes). If you remove restriction then what? Another restriction is the throttle plate. Does openning the throttle increase power? (another easy question). This is real basic simple physics guys.

07-25-05, 11:30 PM
Hi everyone, I'm just getting back from the shop at midnight here. The job started late afternoon here and had to sit around for about 3 hrs with a fan on it to cool it down enough for the techs. I'd say the they actually worked on it was about 4.5 for today. So far, the driver's side is out and replaced with the JB headers and the passenger side heat shield is off as well, which is hardest part of the installation.

Basic procedure for this particuliar tech was;

1. Remove the Y-pipe, which was 2 bolts for each of the 2 cats and 1 resonator.
2. Remove the catalytic converters ( 3 bolts) and had 3 break due to heat, no major damage.
Remove the O2 sensor from each cat.
3. Unbolt and support the power steering rack, 2 bolts for the each support and 1 bolt for each
wire/tube harness, and 4 17mm bolts for the rack assembly.
4. Undo, but not remove the 2 bolts holding the engine mounts for each side. Lower the engine
mounts about .5-.75 inch.
5. Undo, but not remove the 2 bolts holding each side of the front subframe, lower about .75 inch
6. Use an tranny jack to raise the engine about 1-1.5 inches.
7. Remove the 3 10mm bolts holding the heatshield to the OEM header, romove shield.
8. Remove the 8 14mm(maybe 12mm- it's late) nuts that hold the OEM headers to the block.
9. Carefully move the trnasmission dipstick, block 1 header bolt.
10. Completely remove the engine oil dipstick.
11. Headers will drop down.
12. Replace with JB headers and new OEM exhaust gasket.
13. Reinstall 8 manifold nuts
14. Reinstall oil dipstick.
15. Reinstall O2 sensor.



Didn;t reinstall cats or y-pipe, so I'm not sure about the fitment quite yet. I will know sometime tommorow afternoon, hopefully we are in good shape. The biggest obstacle is those darn heatshields, everything else looks fairly simple. It really sounds harder than it really is, but it's very time consuming.I'm sure I forgot something, I'll see tommorow. I'll post pics up sometime tommorow, just too tired right now.

07-26-05, 10:35 AM
Just got off the phone with gawd. The shop worked all night to get the install done and both sides fit great and he has started the car!!!

He will be driving the car for several days before dynoing to allow the ECU to adjust and provide a good reading. I will be sending everyone on the list the manufacturer information and instructions to send a deposit for their order.

07-26-05, 02:43 PM
ORDERING INFORMATION

Ok, here is the deal, everyone needs to give a big round of applause for the people that joined the committed list. This was required to get enough committed buyers so that the manufacturer would build the first set without getting any money up front. Good job and thank you guys!

Now, I asked Loren Barnes at S&S Headers (the owner, fabricator, manufacturer) if I should post his contact info online. He said yes. So with due thanks given to the committed list participants; here is the contact info for anyone that wants to buy these but has not yet joined the list.

PLEASE limit you phone calls and questions to him to questions not answered already here on this thread. We do not want to bog him down with repetative questions. In fact if you have questions just post them here. If it is best answered by Loren I will say so and suggest you call at that point. If you want to place an order you can of course call direct.

Here is how it works. Send in a $200 deposit. You will be put in line based on your order position. When your set is ready you will need to pay the balance of $400 + s/h.

Remember, he will only make minimum runs of 20 sets. If you order now you will get a set. If you wait you may have to wait a while until there are 20 orders. There is no guarantee this will happen.

S&S HEADERS INC.
6042 N. 53rd DRIVE
GLENDALE, AZ 85301-7775

ph 623-847-9000, fax 623-847-9009 , email: techtalk@ssheaders.com , http://www.ssheaders.com/ Contact: Loren or Betty

JBrady

07-26-05, 06:01 PM
I don't have the list of current orders but Hollywood above is a G430. There are nine GS430s on the list.

Honestly, with these making noticeable power at only 3000rpm we should see a bunch of people get them. In fact the shop that installed gawd's set has a custom set of shorty headers on an SC430 (same engine as GS430 and LS430) and it has noticeable power increase. As I said before the 430 is a bigger engine with less efficient manifolds... it should respond better than the 400 cars.

One other point, if for some reason you did not install your set, certainly you could sell them for near breakeven or maybe a profit depending on supply and demand.

07-26-05, 06:37 PM
Well, I donated my 2.25 into 2.50 Y pipe and 3 flanges to gawd who had a small shop piece a 2.25 Y together. I was leaving town and didn't have time to make any tests but he felt it lost power. On the dyno it was within 1hp of the stock Y. I don' think it had sufficient pipe length after the merge collector to work properly. At this time gawd is running the stock Y and feeling gains. He intends to dyno both Y pipes with the headers.

Based on the above results I am engineering a new Y pipe design. It won't be ready for a while but is REAL easy to install and since the stock pipe is making power that is not an immediate problem.

I will of course keep the board informed.

07-26-05, 07:39 PM
DaveGS4 Forum Administrator
Just to clarify from what I understand from John's posts the MINIMUM order is 20 sets for a run of headers, 20 is not the the maximum that can be ordered... so as long as you get your order in before the first build set closes you should be fine (JB please correct me if I'm wrong).

Morris - I asked JB about having these before Lexfest and he said not to count on it. I was going to see if SRT could do the install while the GS was already up here.

PS, those that put down money a long time ago to make sure these happen should go to the top of the list for delivery cough cough

Here are some pics from the install, I'll have some more up tommorow... JB vs OEM




Mock fit in heatshield, not installed this way




07-27-05, 07:25 AM
Dave, you are correct. Loren needs to run at least 20 sets at a time. Obviously they cannot be built all at once. He will probably run the first 20-30 sets and then additional runs all based on this INITIAL VOLUME of orders. If people do not get their deposits in by next Friday there is no way of knowing how long before another 20 orders are recieved. Example. If a total of 45 orders is recieved, and he runs 20 in the first batch, he will run 25 in the second. If then another order is rec'd it will have to wait for 19 more

Target date on production is 4 weeks from next Friday.

Yes Dave, you are in the 1st run

07-27-05, 07:33 AM
Morris, you are correct. More efficiency all around. Quicker spool, more power at ANY boost level, cooler engine at ANY power level.

07-27-05, 07:42 AM
No CARB certification will be sought. All aftermarket parts must have a CARB E.O. # to be "legal". That said ironically these could actually be BETTER for emissions than the stock manifolds. The superior efficiency could bring the cats to operating temps faster creating less cold start emissions. They will certainly pass the tailpipe test. The visual is the only concern. MANY cars in California are heavily modified and "somehow" get through. I would suggest some searching for how that is happening.

The headers have no provision for mounting the heat shields. I really cannot offer a good way to secure the shield in place. Personally I would suggest cutting the shield into a top and bottom half and placing the top half over the header, secured with wire for the test ONLY. This would probably get you past the visual as the view from the top would be normal. Afterwards, remove the partial shield to avoid rattling and rubbing on the coating.

07-27-05, 12:15 PM
The Jet Hot does a good job keeping the temps down. It is a good idea to buy some heat wrap to cover any wires, brake lines or A/C lines that come close. Otherwise, no, the heat shields are not needed.

07-27-05, 01:39 PM

JBrady

07-27-05, 02:22 PM



OEM gasket after 60K


Header bolt


Motor mount screws



Mounts undone and partially dropped



Oil dipstick stuck between OEM headers

JBrady

Steering rack mounts 17mm - 2 on each side
Still assembled


Disassembled



Circled bolt (far left) is one of the 4 that belong to the front subframe




Catalyst outlet and gasket


MY impressions so far are fantastic, the car pulls very hard in the midrange between 3K - 5K rpm, which is great for me on the highway due to the 3.76 gearing. I didn't notice any gain or loss on the low end , but there is a little umph up towards the redline and the car lunges slightly right after it shifts gears. The exhaust sounds a bit throatier under acceleration, but I couldn't detect anything at idle or while cruising around town.

Hopefully, dyno number will be available sometime early next week

JBrady

07-27-05, 05:08 PM
You should be able to order a set uncoated. The stock GS400 heat shields from 1998-2000 physically fit over the headers. gawd has a picture of just that above. Welding on brackets would work but not simple to do. The drivers side will be very close and may not clear the steering column. I guess you could cut the shield away around the column. I would still have them coated after you are done to preserve the metal and prevent corrosion as well as keep the heat where it will do the most good... maintaining velocity. All of this would have added substantially to the cost and is not needed from a function standpoint.

07-27-05, 06:02 PM
98-99 heat shields physically fit. gawd has pictures. I posted pictures of the prototypes with heat shields. There are no mounting tabs to secure them. This would have added considerably to the cost.

Regarding the flanges at $23.50 each. At this price Loren will not even offer a dealer discount. This is very inexpensive for low volume production 3 bolt flanges in 3/8" steel. All 1990-1997 car owners will need these to build downpipes. This was explained in a number of places and via email. The EGR flange at around $5 is cheap and needed for anyone wanting to keep EGR on the same year cars. This flange will need to be welded into the downpipes and aftermarket flex line installed from the new EGR location to the factory EGR engine location. Again, describe in email and in ths thread.

Only 98-00 heat shields fit over the headers. There are no provisions for mounting them.

The 1990-1997 EGR flange cannot be located in the stock location. Weld the available flange in the downpipe you will need to have made. As I addressed in the email to buyers, there is no absolute guarantee that these will fit in the early cars. They should but until they are tried we cannot know for certain.

07-28-05, 10:41 AM
In addition to the generosity of the above members additional thanks is due to DaveGS4 for not only getting this project approved with CL but also staying supportive the entire time AND for his latest help he has sponsored gawd's next dyno session!!!

Big thanks Dave

07-28-05, 04:58 PM
gawd just told me the car just gets faster everyday!

Even in 99 degree Houston humidity the car is snapping his head like it was ice cold outside. He did a pull as we spoke and the sound of his SRT ripping through the revs sounds GREAT

He may be able to record some sounds for those interested.

He reports the power starts at only 2600rpm

This is EXACTLY what we wanted. Great power, Great torque, no extra noise.

He says it pulls very hard up to 5800 and then the power levels out to the 6200rpm shift point. Now, it is probable that the power stays even from 5800 to 6200 and is not gaining as fast as from 2600 to 5800. Still, the butt-dyno is not a quantative tool. BUT the feel of the pants improvement is seriously good stuff. I am jealous I can't get this for at least a month

Looks like the dyno is on for Monday.
You bet . Actually, if I had traction the night I ran 14.22 at 99mph I would have definitely gone high 13s. This was done on a stock 99 LS400 with a modified stock airbox at a raceweight of 4000lbs.

3.77 LSD and it would have been around 13.7.

TC plus drag radials 13.2.

Headers and exhaust with above POSSIBLY 12.9s.

A GS400 should be able to run 2 tenths quicker than my LS400 all else equal.

A 100hp shot of NOS and we would be threatening 11s.

07-30-05, 08:52 AM
Yes, you are correct, if the dyno shows a nice increase in power I am certain the line will grow longer.

That said, MANY if not most do not understand what dyno testing REALLY tells you about a part.

Most people want to know one thing and one thing only... how much power did it gain? Of course they are refering to PEAK horsepower (or killowatts in some reqions). While it is always good to gain peak power what is actually more important is power/torque under the curve AND responsiveness of the engine. These numbers are partially shown in dyno runs but the nature of an inertia chassis dyno (dynojet) does not lend itself well to measuring transient response.

Lets compare an actual situation right here. gawd had a 2.25" Y pipe welded up with parts that I donated to him. (these were for my car but I felt the GS400 needed them NOW) Unfortunately the person that welded it up did not have a lift and therefore bench welded the system and it did not fit correctly. BUT, the main problem is that there was not enough pipe length after the collector. gawd immediately noticed the car felt sluggish accross the power range (compared to the stock Y pipe) and he didn't like the sound. (sound turned out to be the misfitting pipe rattling and an exhaust leak). He dyno'd the bigger pipe against the stock pipe and found that the bigger pipe actually gained 6tq and the power was within 1hp.

So, what do we have? A gain in torque should indicate that this part is better than the stock pipe. HOWEVER, it FELT lousey. How many people would spend money on a part that made their car FEEL slow? Even when the dyno said it helped?

Now, gawd has had the bigger pipe reworked, fit corrected, 6" length added after the merge. He did not have a chance to test it before the header install but he reports it feels at least as good as stock if not better

He intends to dyno with both pipes so that additional info will be helpful but for now it looks like a good idea to upgrade Y pipes on header equiped cars. Based on the data so far I am actually working on a different Y pipe design that should further improve power AND response. If effective it should be a good upgrade for all GS400s with or without headers.

Back to the Headers....
Many posts back I described the "feel" of 20+rwhp as more or less the "feel" of a stock car in hot weather vs. cold weather. My LS400 runs a solid 2 to 3 tenths quicker in cold air than hot air. Drag racing dyno charts will tell you it takes about 10hp for every tenth quicker for a car in the 14 second range. So, is my car ACTUALLY gaining and or loosing up to 30hp??? On ONLY air temperature???

YES
How is this possible?

The answer lies in the fact that colder air is denser air. This means that there is MORE actual molecular weight in any given VOLUME of air. Engines pump volume. Density determines MASS at any given volume. Mass determines power NOT volume.

Also, our engines have highly sophisticated electronics and both the fuel flow and the ignition timing is altered as air mass increases and air temperatures decrease.

Even though this is LONG and BORING to some... it is actually a simplified tiny fraction of information intended to make a POINT.

The POINT is the FEEL of you car when you drive it.

My previous estimation appears very accurate. gawd's car FEELS to him like it does in very cold air when in fact it is around 100 degrees and very humid in Houston. So, the car FEELS like it picked up 20-30hp. This means several things. The car is more fun to drive. The car is almost certainly quicker, much quicker, than without the headers. This also means that it will be QUICKER still in cold air.

Now, what will the dyno numbers say? We do not know yet. But WHATEVER it shows we already KNOW these headers are working and working very well at that. This means at the very least we have nice gains in responsiveness. This will USUALLY be seen as increased mid range torque. gawd is reporting a noticeable gain from 2600rpm up. The problem is that it is very hard to dyno these automatic transmission cars from low rpms. They will try but we may not get that data.

I guess the best way to describe the headers improvement is as I did above. Your car will FEEL like it does in very cold air when the air is actually hot. It will FEEL even faster in cold air. I would be HAPPY to race a GS4xx with only headers against another GS4xx without them. I would not need a dyno sheet to be confident in placing a wager

So, again, I am sure that a nice increase on a dyno chart will sell more headers. That actually is not helpful or hurtful to me. I do not get a cut off the deal. But, as I have tried to illustrate above it is not always the car with the bigger peak dyno number that is the quickest. In the Corvette and Supra and other hi-po car world it is VERY COMMON indeed that it will be the "weaker" of 2 cars (based on dyno charts) that WINS the RACE

07-31-05, 08:42 AM
If you add in other factors such as a high stall TC and different gearing and then consider the different types of dynos, weather variables, other mods to the car etc. it becomes VERY difficult to use the dyno numbers as an absolute standard.
That said, dyno runs can certainly be beneficial for comparison purposes on the same car and same dyno taking into account weather etc. As they say "Use for comparison purposes only, you mileage (or HP) may vary".
I am looking forward to gawd getting some good pulls on the dyno now that his ECU has had some time to compensate for the headers.
I like what I'm hearing so far though!
Yes, dyno numbers are a usefull tool IF DONE CORRECTLY and if USED CORRECTLY. That said consider the many many conditions that are NOT measured on a dyno pull.

Part Throttle Tip in Response: This is how responsive the engine "feels" under normal driving conditions. Does the engine "feel" crisp and powerful even without using full throttle? This is a BIG part of the joy of day to day driving.

Fuel Economy: While a dyno that takes A/F readings will tell you the BSFC under full throttle it does not tell you the part throttle efficiency and that is what determines fuel economy.

Off The Line Power: On a stock torque converter this is the torque available at 1800-3000rpm. With a 2800 stall TC this is 2600-3500rpm (both are target ranges and not absolutes). This is how well the car responds from a standing start.

RPM Drop Recovery: This is how the engine response during gear changes. How much torque is available when the next gear is engaged AND how well the engine accelerates going from a high RPM and then abruptly dropped to a lower RPM while still under WOT.

Part Throttle Balance: The peakiness or lack of when maintaining part throttle 50-80% load. Definitely effects how "driveable" a car is during driving manuevers (hint, the throttle is a variable control not an on/off switch).

And many other part throttle/load/response conditions that make up the very complex mapping needed in an ECU controlled engine.

Now, looking at what a dyno DOES measure it is important to understand HOW to interpret the information.

Peak Power and Peak Torque are what almost everyone wants to know for "bench racing" discussions. These are fun numbers and worth knowing BUT the IMPORTANT full throttle dyno information is the POWER UNDER THE CURVE. This is the average power (torque and HP) for the RPM range used. Of course "Off The Line" is important for drag racing type competition but once underway the engine will never drop below a certain RPM. The average power between say 4000 and 6300rpm is more important than peak numbers. While still laking the responsiveness data this AVERAGE power under the curve is the best data available from a dyno. When was the last time you heard someone compare power under the curve data?

Like I have said before there is MUCH more to the story than simplistic measurements. Considering the above driveability conditions let me pose a couple questions:

Would having a much more responsive car that gets better mileage AND performs better be worth spending money to achieve even IF peak numbers were not increased on a dyno?

Would you spend money to gain peak numbers on a dyno even if the driveability and in fact real world performance went down or didn't improve?

08-01-05, 08:55 AM
The SRT addresses the fact that the factory MAF is restrictive. They do it by placing the MAF element in a larger diameter housing. The increased flow relative to the factory MAF calibration makes the car run VERY lean. This requires a correction to the signal to the ECU. SRT calls this part their Race ECU. If you tune the ECU to run a slightly leaner mixture than the factory setting under full power you will gain power. However, each application tends to be slightly different as the factory OBDII programing is dynamic and even resetting it tends to produce a variable in the relearn. gawd ran a baseline dyno on his 3.77 LSD and SRT intake equiped 99 GS400 prior to the header install. His torque was good at 260 but the power was on the low side at 230rwhp. A/F ratios were too rich at 11.5-to-1. His ECU needed a leaning to closer to 12.5 or 13 to 1 for best power.

So, to answer your question, IMO the SRT is currently the best aftermarket peak power intake for the GS400. There are some other tuning considerations including tapered pipe and resonator chambers that could improve the intakes performance and possibly regain any lost low RPM power. Since no one is making this theoretical part YET... the SRT is the best choice for PEAK performance but not low end performance. When in comes to confrontations such as the one gawd had in the street stories section of CL... the SRT was definitely helpful.

08-01-05, 12:20 PM
Thank you for taking the time to research and read what I have already written. Some will PM or post a repetitive question and actually say "too much to read, please answer my question". Although I generally do answer the request is basically saying "I am too busy too read but you should take the time to answer me". Truth is, I could read almost all of the posts I have made here in less time than it took me to put together a couple of the more complex posts I have written.

Now, to your question, you want the primary pipes to join together forming a TOTAL angle between them of 30 to 45 degrees. Do not slash cut each pipe at 45 degrees as that would yield a total angle of 90 degrees (much to wide). The tighter the angle the better in some ways. The outlet pipe is the center pipe and 2.50 is a reasonable choice although I intend to experiment with 2.125 primary and 2.50, 2.75 and 3.00" center pipes and also step centers and alternate merge configurations. For now 2.25 into 2.50 should be OK. Create at least 10 inches of center pipe before you split it back into the dual muffler section.

08-02-05, 10:05 PM
Yes, the dyno was ran, power is up. Before I comment further check out this post from gawd.

https://www.clublexus.com/forums/sho...d.php?t=172937

JBrady

08-04-05, 11:03 AM
Guys, just spoke to John and he's working diligently to get those charts up today. Until then, here are some quick pics.





08-04-05, 11:28 AM
Now, what will the dyno numbers say? We do not know yet. But WHATEVER it shows we already KNOW these headers are working and working very well at that. This means at the very least we have nice gains in responsiveness. This will USUALLY be seen as increased mid range torque. gawd is reporting a noticeable gain from 2600rpm up. The problem is that it is very hard to dyno these automatic transmission cars from low rpms. They will try but we may not get that data.
Now, back to the dyno runs just completed. While it is normal and usual for people to want quick "sound byte" answers to their quick oversimplified questions... the truth is that you MUST know and compare the FULL range of information gathered in order to draw logical and acurate conclusions.

So, that said I am NOT going to just type in the peak numbers. I know human nature and that will be to skip all this and look at the peak numbers.

Instead, I am going to focus on another GS400, owned by CL member Halo, who was also had his GS400 dyno'd same day same dyno. The reason is that in those 2 pulls the peak numbers were within 1hp and 1tq of each other. NOW, if you look at the numbers between 3500rpm and 4000rpm the torque figures varied by as much as 15rwtq with an average difference of about 12rwtq. WHY? Same car, same dyno, back to back runs, no changes. You would tend to think that it was because the car was hot. Actually, no, the higher recorded run was the LAST run

So, what I am saying is on this car WHAT IF he had made some ineffective change, say added different spark plugs or grounding wires or changed air filters, etc. The quick conclusion would have been "it gained/lost 1hp and it gained/lost 20tq in the midrange". Ask yourself, would that be a reasonable conclusion?

Now, Halo's car put down 246rwhp and 253rwtq. Power peaked at 6000rpm holding nearly peak to fuel cut at 6350rpm. Torque peaked at 4300rpm. This car has the SRT intake/early ECU. I am not aware of any other power mods.

gawd faxed me 4 dyno pages. Halo's 2 runs were on one page. One page contained 2 runs, one was Halo's best and the other gawd's best. These 2 pages were relatively easy to read. The other 2 pages each had 4 runs on them and decifering which run was which as the lines crossed at at LEAST 8 points is not as easy.

Considering that the data above on only Halo's car showed a big variance in mid range torque it is also inconclusive about other mid range chart data.

A CRITICAL piece of information is missing as none of the cars had their air fuel ratios measured. Based on gawd's baseline his car WAS reading 11.5 to one ratio. This is MUCH to rich for peak power. Halo's car is making what I would expect to see a stock engine with the SRT intake and gawd's baseline was 15rwhp less.

I just had a LONG conversation with gawd and he helped decifer the various multi reading sheets. With this I will post the results soon.

08-04-05, 01:01 PM
Thank you, this is correct, we have ONE car running ONE set of before and after pulls on the ONE set of headers in existance. No tuning was done of ANY kind. The fact that I am NOT the "company" and not doing this for profit puts this entire exercise in a MUCH different light than a typical marketing promotional "dyno" test.

With all due respect to chuckb and Morris... the very reason that I have been spending a great deal of time explaining this IS to HOPEFULLY preclude quick snap judgements.

AGAIN, we have ONE car that was NOT tuned correctly on the BASELINE and then that SAME car without A/F ratios (tuning data) on the follow up test dyno. NEVER will a manufacturer that is advertising performance information do this.

That said, we have incomplete data. No A/F ratios, NO usable data below 4600rpm. Previous peak torque seems TOO high. Torque on Halo's car varied 15rwtq on back to back runs below 4200rpm. Neither gawd's car or TXGS's car had full throttle/full load info below 4600rpm. gawd's baseline torque peak occured at 4300rpm. Before and after torque at 4600rpm was the same for the baseline and for the header runs. This number is 236rwtq.

Horsepower increased from 4600 and gained 2rwhp at 5400rpm, 7rwhp at 5600rpm, 10rwhp at 6100rpm and 15rwhp at 6300rpm. Peak power was at 6200rpm at 237.5rwhp.

Again, there is something wrong with the tuning on this car. No tuning was made. If the A/Fratio is still 11.5 to one there is 15+rwhp to be gained in this alone. This car should have in the neighborhood of 250-260rwhp when the A/F problem is corrected.

Additionally, the dyno conditions were miserable for making power, 99 degrees, high humidity. As I have said before my car makes SUBSTANTIALLY more power in cold air. This is not the final word on the power these 1UZFEs are capable of. It is really just the beginning. Stay tuned.

08-04-05, 01:08 PM
An example of the inconsistency of the dyno pulls. Comparing TXGS's GS430, with a factory torque rating of 325tq at 3400rpm vs. Halo's best pull on his GS400 factory rated at 310tq at 4000rpm, Halo had 75rwtq MORE at the supposed 430s PEAK rpm of 3400rpm.

Do you think this is because TXGS's car is just weak? Absolutely not. This dyno operator was not able to properly load the cars and the range was all over the map below 4600rpm.

We need more and repeatable TUNED dyno info before we know more.