Lvangundy

Just making another thread for this airbox discussion.

Lvangundy

LexusWhoSmokedU --

"I have a friend who works at a performance shop so we got to really find out what air filter set up worked out the best. I first began by taping and cardboarding to make the area around the filter only take in air from below the headlight and the lower part of the bumper. I then began the test with the stock Toyota filter, housing in place, and the ducting to above the radiator there. On that run I had about 170 RWHP max. Then, I removed just the plastic air ducting above the radiator and made sure to seal the area so that no radiator air was getting into the intake. I had a 178 RWHP max. I then removed the front piece to the filter housing, wrapped the edge of the filter in tape making it seal and then just secured the clamp so that you could see the entire filter cylinder. I made 185 max RWHP. Then I removed everything and descreened the MAF and made sure there was no air leakage in from the hot radiator. This produced an astonishing 195 RWHP BUT the car did not run all that well and the service engine light came on alot. I put the MAF screen back and attached the Rod Millen Intake I bought with a K&N filter. It made 186 RWHP. I was happy with that but then decided to run without the K&N, open intake, no filter, with just the Rod Millen intake on. 197 RWHP is what I managed AND it ran really well. The Rod Millen intake is what I suggest to anyone wanting better flow. The cast MAF adapter is the same dimensions as the MAF housing so it doesn't restrict, my car ran smoother, and it sounds great. I thought this all might be some help but whatever you do, get rid of your stock intake from the filter housing forward. By the way, I used to get only about 13 MPG in my car no matter where I went. Once I replaced my intake, I easily manage 24-25 MPG on the highway. The only problem is that if I floor it all the time, it uses more gas. A more freely flowing intake will always improve gas mileage. It is the manner in which this more free flow is used that causes problems in gas mileage. Oh and one last thought. The intake was the first of my performance work. My last dyno showed 273 RWHP at 5,823 and then 291 torque at 5,236. The exhausts on these cars rob more power than you know...
Sean Gillette"

Lvangundy

LexusWhoSmokedU

"
The car, until this Christmas is naturally aspirated. Rod Millen intake, I polished the MAF, MAF adapter, put PVC from the MAF to the throttle, polished throttle body, polished the intake, ported the exhaust, took off rear catalytic converter, and have dual straight pipes to the rear (no mufflers). The car passes emissions with flying colors. I also defeated the EGR circuitry and just capped it all off. I spent alot of time though polishing and wound up with a mild porting on some parts. I also made myself a homemade transmission kit. I made a controller that feeds impulses to the computer from the odo pickup to make it think the car is rolling and then I also use a switchable adjustable resistor for the ECT for first gear to cause the valve for first gear to engage more slowly and allow the tranny to slip so that I can put the car in neutral, rev to 6100 and then pull the car into drive without destroying anymore flex disks and driveshafts. The car launches through first gear and runs 5.3 to 60. My only problem is that this will ruin my tranny in no time. I ran it in the quarter and managed a 13.3 at 104 MPH. Not bad for a standardly 8 second 0-60 beheamoth!
"

Lvangundy

LexusWhoSmokedU


Well, basically when I went to buy a car I was going to keep for a while, I did some research. I learned of the 91-92 LS400s being the most reliable but I also knew that they had brake problems like crazy in 90 so I nixed it and the problems were not fully cured until 93 and 94. The part that caught my attention, was where the engine and drivetrain mostly came from. Toyota's F-1 racing team used this same block and only had slight differences. For instance, the F-1s went to 16,000 RPM. The crank and block basically the same. They had cams which were used up in one race because of their design. Obviously, 16,000 RPM is not a reasonable goal to shoot for, but it at least gave me ideas. I am about to rebuild the entire engine with forged just about everything to handle the N20 setup I am adding and also to handle a 16 lb eaton supercharger. I liked the LS for its room and comfort and ease at which I will be able to put in an intercooler and intake plumbing. I would like to update the front end and rear to a 98 style and that will prob be a spring break project. MY Christmas project is going to keep the car in my garage for nearly four weeks. But when done should run a 10.5-11 in the quarter with about 650 RWHP. I am having new cams custom built to allow for shifts at 8,200 RPM. The HP curve should peak at about 7800 or so. I would really like to put the supercharger on at the same time, but college and Christmas gifts will keep me from being able to afford it. By spring break though, I am hoping to have the supercharger on there and running mid 9s. After that, I am done. I cannot run correctly at the track now. I wait at the line for three seconds to go so that I don't need to get a helmet and put a roll cage in the damn thing. Currently, I run only 235/45/17s on the track but I am sending the old stock 16" rims and having a welding shop cut them and weld them together to make a wheel to fit 345 wide tires in the back. I want the car to almost seem stock so no huge body kits or anything. I just want it to look nice, sound good (exhaust and stereo) and run like hell down the track. Now, to answer questions... The intake suggestions I will go ahead and take pictures of my car with each different set up I was describing because yes that was confusing when I read back over it and it is hard to describe but the BEST AND CHEAPEST route I have found was this:
1.) Remove the air intake which routes to above the radiator and is about 2 feet long and 9 inches wide.
2.) Then take off the plastic piece which wraps around the filter to hide it. Itis the piece that looks like a bowl and connects to the air intake that would have been above the radiator.
3.) Take electrical tape and start wrapping the very outer lip of the air filter (plastic that seats up to the plastic piece that comes from the MAF) Wrap the edge about 5-6 times to make the diameter of that plastic seating piece wider and also the tape is soft and provides a seal. Put the filter in as if you had the plastic piece on it but just push it up to the plastic piece coming from the MAF Clamp it down and you are done. 25 cents of electrical tape and it will perform almost as well as the Rod Millen ($220 from Lexuspros.com) It also filters better since it is the factory paper type but being open really allows the engine to scream.
Many people's LS400s I have serviced all had a problem with seeming to choke off when floored and it got to 5700 RPM. This is because the stock intake system was designed for quietness, fuel economy, and lower emissions. You will not fail emissions, as long as the car is not floored all the time, economy goes up, and the sound you get is awesome. Go under a bridge at full throttle and you will sound like the F1s. I swear on my life you will worship the sound your car makes. All my friends with Trans Ams and Mustangs all think my car sounds better than anything they have ever heard. Sorry, but it has been raining in Houston and I can't take pics until later tonight or tomorrow. It is 40 degrees here and my car is running SOOOOOOOO well. I love cold weather. By the way, for anyone who doesn't understand the quarter mile stuff and 0-60 here is a quick list of kills I have made:
TT Supra 96 46,000 spent on mods raced to 80 and I killed him.
02 Camaro Z28 6spd raced quarter and killed him
03 Mustang GT ??? tranny but beat him all the way from Houston to Brenham. 155 is quite fast by the way. He topped at 150. (3am in the morning no cops But for anyone who doesn't believe my dynos or times, bring your car to me, let me work for about 24 hours and I can guarantee similar times and numbers. I will list the dyno charts too this weekend. Along with my track slips. I am going to run the car this weekend again cuz its colder than last time I ran. I'm not saying my car is faster than all Z28s or anything like that. I know that with the right driver and all the free mods the LS1s have, they could kill me. But I really enjoyed trouncing the hell out of a supercharged S2000!!!
Sean Gillette

Lvangundy

I think I've done what you described for the airbox mod.

I did it really quick, slapped some electrical tape on and kept the intake redirector (over the radiator) because I figure this part does provide some air from the front of the car..maybe it gets hot as it passes over the radiator? I also removed the little hard plastic piece that covers the lightbulb connector socket. I think jbrady described a rubber seal, but I haven't found one on my car for the headlight.

I'll take some pics today. The sound is louder than stock, but not as loud as the K&N was. People on the freeway could hear the K&N, heh I could see them look over as I kept the car in 2nd or 3rd gear.

JBrady

Ok, here is the list so far of Seans mods:

1) Rod Millen intake with cold air box.

2) Polished the MAF and the RM MAF adapter

3) PVC from the MAF to the throttle body

4) ported the exhaust

5) Removed entire exhaust from the catalysts and replaced with 2.5" straight pipes with NO mufflers.

6) defeated the EGR circuitry and just capped it all off.

7) Alot of time though polishing and wound up with a mild porting on some parts.

Ran it in the quarter and managed a 13.3 at 104 MPH

Now, I intend to meet up with Sean at the track and get some first hand information and hopefully some pics and vids. As of now, here are my thoughts and notes on the above.

Number 1: According to Seans post the Rod Millen Intake was tested alone and resulted in 186rwhp vs. his stock 170rwhp. His test with the stock air filter housing and air filter with the housing cover removed and a fabricated cold air box resulted in a near identical 185rwhp so it may not be necessary to purchase the Rod Millen part. 15rwhp for this alone is impressive but well within reason. 84rwhp to go

Number 2: not sure what he accomplished here or what if anything power wise was gained.

Number 3: this improves the flow from the MAF to the throttle body, again no specifics yet on this mod.

Number 4: need specifics

Number 5: obviously a BIG help. He doesn't have an X or Y or H pipe just 2 separate pipes with no mufflers. My guess... 25-30rwhp... maybe more. Of course most of us will want muffling of some sort and that should be very doable... possibly with no decrease in power... remotely possible with a slight improvement over no mufflers do to scavenging of a good Y or X pipe configuration.

Number 6: EGR shouldn't hurt WOT performance but who knows?

Number 7: need specifics.

Lvangundy

Good summary jbrady!

Ok- Here's my attempt at the airbox mod from what i could understand from LexusWhoSmokedU's post.

Yes, I used electrical tape, and was in a hurry and it was a night, I figured it would take 5 minutes so I ran outside and did it. I can clean up the tape later.

Lvangundy

Heres a shot from above and behind pointing to the plastic cover I removed that guards the headlight connector.

JBrady

Actually... NO...

You want to wrap the tape around the EDGE of the filter. The edge is the part that the clamp contacts. This is because the filter is not wide enough with the front cover removed and unfiltered air can be pulled in around the loose filter/clamp area.

Take the filter off, hold it in your hand, wrap the tape around the edge around 3 to 4 times completely around, place the taped edge inside the clamp and close the clamp. Your filter should now be held in place without leakage.

Another option, one that I had done before modifing my airbox lid, was to cut the edge off an old filter and using it to take up the loose fit.

Lvangundy

So the filter needs to be reversed?

Lvangundy

Ok..

I think I did it right this time. I swear I have the most backwards thinking process..

Flipped the filter around, no tape this time and I see how the clamp fits the filter edge. Much better fit. LOL.

Will take a pic tonight.

Thanks to jbrady and lexwhosmokedu-

JBrady

Well... Ah... I didn't notice that you had reversed the air filter in you "tape" picture :eek:

Yes, keep the filter in its STOCK position. Mearly use the tape to take up the slack that the front cover leaves that the V clamp holds on to.

Now, the mod that I did on my LS400 creates as much flow and KEEPS the stock air feed over the radiator. This feed is cold air and also seals off some of the engine compartment heat. YOU MUST fabricate a cold air box. Look closely at my mod and you will see I am actually using cardboard to block off engine heat/air flow. I am drawing cold air from around the headlight area and the stock cold air feed over the radiator. The modified front cover helps form both part of a cold air box AND supports the factory cold air feed.

Lvangundy

What's the status on the pics of lexwho--'s car?

lexwhosmokedu also suggests taking the air dam over the radiator out..I think this would keep colder air coming from the grill..any ideas?


J- Do you have any better pics of the heat shield?

Also - when dyno testing, the environment is closed and usually a fan is running. Don't all these mods to the airbox yield barely noticeable differences especially when the external conditions to the car are the same every single time? The only thing that's changing is some of the airflow to the MAF and intake.

JBrady

Here are some photos of another members 1st gen LS400 air filter housing mod. In addition to removing the plug around the headlight he also removed the one for the side light access. Like my mod he kept the stock air feed tube.



He also states that there is a gap between the radiator and filter headlight area that allows cold air and gives the following picture but I can't vouch for the area as I have not done a first hand inspection.



Here is his modified lid but I would recommend cutting the hole in the lid larger, exposing the entire face of the air filter element.



The important thing is to create a solid mount for the MAF, block the engine heat, reduce the all restriction to the air filter and provide as much cold air to the filter as possible.

JBrady

This thread is titled "Airbox mod" and therefore I am adding what I can to that end. The other engine mods listed above probably need a new thread appropriately titled so I will start one. Below are the links I recommend reviewing by all interested in the air box mod.

My airbox mod thread:

https://www.clublexus.com/forums/sho...threadid=55111

1st gen thread:

https://www.clublexus.com/forums/sho...threadid=56619

1st gen additional thread (see my above comments on the 1st gen):

https://www.clublexus.com/forums/sho...threadid=55911

The inspiration for my mod and a complete step by step for an SC400:

http://www.users.bigpond.com/pgscott/BFIDIY/BFIDIY.html