SC400TT

iTrader: (4)

Proof, Proof, Proof... While I understand you guys do not want to waste money, it is pretty clear that these headers are going to help improve low end performance, something the SC400 really needs. How much is a real toss up. Anyone of you could put on a set and possibly show some great gains, and then another installs them, and the Dyno does not show it...Many, many variables...But, if you are going to stay NA, and want to gain performance, and do not want to spend too much money, do the following:
1)Purchase a set of the JB Headers
2)Design and install a proper and efficient exhaust system that scavenges well
3)Purchase a Dragon TQ Converter with proper stall speed
4)Consider some type of engine management for air/fuel tweaking.

Should be much more responsive...

Ryan

Hollywood

There is no point when they are fubar'd from the dyno operator. Minor changes in the calculations make a major difference.

If my headers were to come earlier I could provide the digital results (power/AF's) by the dynoing by a master dyno technician who wont **** **** up He has a mustang dyno which induces load for the most accurate dyno results and a motec (over $2K) sensor for air/fuels.

bitkahuna

iTrader: (20)

Well that's a BUNCH of money (prob. $4-5K). Let's just focus on the headers alone. Assuming $600 for headers and $500 for installation, that's $1100. For that money someone should probably do the TC upgrade instead which will give much better real world gains.

But I'm not saying these headers aren't worth it. We just have very little to go on right now.

RMMGS4

iTrader: (5)

I too would like to see a before / after dyno run from some of those who will be installing these headers.

Using Butt-o-meters and responding subjectively with a bunch of "WOW "and "Oooo" responses doesn't mean squat to me.

It is not critical what type of dyno is used as long as it is operated consistently. It is the delta value we are looking for, so I really dont' care what the HP reading is; I just want to know the gain. As long as both tests are done under similar conditions and no other changes, that should be a decent analysis.

For that amount of money I'd like to minimally see a 20HP gain. I don't think that's asking too much and any power more than that is great.

Hopefully I can convince redgs4 to dyno his car since he and I have dynoed our cars in the past. Our mods are very similar and we are within 5HP/TQ of each other.

Cannonbear

but where would you want the 20 hp gain? At peak power or throughout the powerband?

RMMGS4

iTrader: (5)

Well for me, low end is preferred, but since the design of the headers dictates the powerband, nothing will change that at this point.

JBrady

Yes, this is a header thread but many who are purchasing these already have the TC.
BUT... to say that the TC will give better results than headers really needs to be defined.
Theoretically a TC will give better 0-60 times due to the ability to launch the car harder than with the stock TC. The TC does not make more power. The improvement in performance is also much more dependent on driver skill. An unskilled driver in a TC equiped car could very easily loose to a skilled driver in a stock car. Once under way driver skill is less of an issue and all other things being equal the header equiped car will make more horsepower and will pull harder compared to a TC.

Using the dollar spent vs performance gained is subjective as MANY have spent $600 and more for center back exhaust systems that generate no shown power increase.

Bottom line is the stock manifolds are not designed to make power. Low noise, reliability and emissions are the design goals. Anyone that intends to maximize or improve their engines output will appreciate the availability of better flowing manifolding.

JBrady

Dyno racing

Who has the fastest dyno car?

RMMGS4, 245hp/250tq are good "numbers" for the mods you have listed. Have you taken it to the track to find out how quick/fast your car/driver combo is yet?

As we have seen dyno numbers are subject to many things, not the least being the temperment of the Toyota engine management.

CinFulxgs

Regardless of HP increase everyone wants to be faster and the TC is proven to do so along with making the car more responsive even on a roll. The general consensus is that it shaves a half sec off 0-60 and 1/4 mile which is what is important.

The headers is not some big HP upgrade as some would hope I don't think, just another Mod that improves flow... although this has yet to be proven in our particular application... I am sure it flows better, but we don't know if our engine sees it as a good thing.

I am sure the more people that put these on and then report on the butt-o-meter the more interest they will generate.

JBrady

Cin,

I almost hate using your post as an example but dang if you don't continue to make it appropriate.

Again, this is a header thread. Not a TC thread. Yes, I understand the comparison and that is why I commented above and elsewhere.

Again, TC does NOT increase horsepower. TC does NOT make the car faster. It does give the car the potential to run 0-60mph quicker due to the potential launch improvement. Fast is top speed potential. Quick is the rate at which any given speed is obtained. I understand these terms are often interchanged so it is worth noting the difference.

Without LSD it is not that easy to maximize the TC gains of around 1/2 second. Just bolting on a TC without the traction and/or ability to put the added torque down is NOT going to allow you to "win" a race. Spinning your tires becomes MUCH easier with a TC and that is a sure fire way to LOOSE a race. Also, changing the stall speed of a TC is something that Lexus could easily do at the factory for no change in manufacturing costs. They set it at 1800-2000 for a reason and changing that WILL affect gas mileage and drivability. Most performance enthusiasts are comfortable with this trade off but the opinion is not universal.

It WOULD cost the factory substantially to change manifolding. Manifolding does effect emissions, particularly cold start emissions. Higher flow cast iron manifolding would be VERY similar in performance to the headers herein but would be heavier. Higher flowing tubular manifolding would be more costly to build than iron manifolding and speed of production would slow.

So far the only data we have on the manifolds is a gain in power, no sacrifice in noise levels and an increase in fuel economy.

You state that these headers are not some "big" HP improvement.... compared to what? Obviously nitrous, super or turbocharging would be considered a big HP improvement but in naturally aspirated form what other choices do we have? Any "big" improvements?

Bottom line is until more data is obtained it is speculative to what the potential is with exhaust upgrades. When someone pops in here and gives yet another negative opinion what does that help? If you are just trying to go on record with a guess to the outcome (without data of any kind or apparently any exhaust tuning experience) does that help the community?

Frankly, I have waited longer than virtually anyone on this board for these headers and I can wait a little longer for a fuller body of data in which to build from. I would suggest that virtually ALL the negatives have been expressed, recognized, addressed, and cataloged. Unless someone has NEW information of VALUE it helps no one to jump in and post baseless grumbling.

Hollywood

Roger that.

How much of this whole thread is already redundant!

I have been on jbrady's side on almost all of this. The only thing that dissapointed me was the information that the dyno tests were innacurate could have been mentioned earlier instead of 3 days later after the dyno.

CinFulxgs

JBrady,

Try not to take threads in here personally, they are really not intended or directed to holding you in anyway accountable for the gains of the header project yet just a sounding board for everyone interested in how to improve performance.

The TC improves performance and according to everyone very much so... no reason to split hairs with how that improvement is phrased, bottom line most everyone here agrees it is the biggest bang for the buck whether coupled with LSD or just wider rubber... you will win more street or strip races with it.

Will the headers contribute as equally... we don't know yet and I agree with you that a dyno may not help with that determination either.

I guess the big question at this point is do the headers work well with our engine and it's fuel management / ECU or do they have no effect or negative effects.

morris

iTrader: (2)

Jbrady, I figure you have to be getting pretty frustrated by now, I just wanted to reassure you and encourage you. What you are doing and have done is extremely valuable to the community, I would guess that even those that are "skeptical or cricical" will admit that they do appreciate what you have accomplished. Please do not mistake the continued questioning for pessimissm or plain old naysaying. I thank you and I know that many others on the board thank you. I'm not sure where you are with all this but if you get to the point where you feel like throwing your hands up, just unsubscribe from the thread for a few days, chill out put things in perspective then come on back.

Congratulations and thanks Morris.

bitkahuna

iTrader: (20)

I know this isn't about TC's but I don't think either Cin or I said a TC increases horsepower. As far as quick vs. fast, mmmkay. So the TC makes the car quicker, ok. I guess the headers in theory have the potential to make the car quicker (e.g, 0-60), and faster (top speed) by your definitions.

Agreed!

Right, and Lexus reasons aren't performance, they're keeping the engine quieter and improving gas mileage by keeping rpms lower by shifting gears sooner.

Sure - an intake, exhaust, and tuning or SRT ECU gets probably around 10-20WHP and some torque. And I'm sure the headers will improve things some further.

Agreed.

Neither Cin nor I are being negative. The availability of custom headers for the Lexus V8 is a great thing. How great and how good a value we don't yet know.

Peace.

TexasLex

Ditto to what Morris wrote to jbrady!