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2JZ NA-T
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5,413 Posts
Discussion Starter #1
Hey guys, in a couple of days im going to be taking the supra down to the Zmax 1/4 track here in NC. I need some help.


firstly, i have a set of the M/T ET street coming in the mail, 26x11.5x16, what kind of tire pressure should i be looking at running?

oh, I have a 95 NA-t with the 6spd conversion and the GS400 rear end, so that puts me to 3.26 rear instead of the tt 6psd's 3.13, but still pretty close.
BL stage 2 kit
t61 turbo,
2.5mm hg ( i have shit for low end torque).
AEM EMS
car makes a little over 450rwhp and 400ftlbs of torque @ 16 psi on pump.

so i also wanted to know if anyone could help me set the 2step settings to boost maybe 4-6 psi off of the line at like 4k rpm maybe? the last settings I got form a member here were supposed to be for 8psi, but as soon as i hit the cut im seeing 15psi (im not too crazy about anti-lag....)

any input would be greatly appreciated guys, thanks
 

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2j GT4294 stickersadd20hp
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1,594 Posts
on the tire pressure I personally started at 20psi, and then as I get a good feel for the track/prep, I lower the pressure to about 10psi.
 

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Registered
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3,236 Posts
Just drop the 2 step settings a cupple hundred rpm and see how much boost you get and go from there untill your target boost. I would imagine the car will not leave that hard at only 6psi unless you slip the clutch out if the hole pretty good. Your turbo is so small that you may have better luck modulating the throttle at the line.
 

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2JZ NA-T
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5,413 Posts
Discussion Starter #4
so you think 6psi would bog down really hard if the clutch is dumped? i dont mind setting it alil higher really.... just dont want to be boosting 16 psi off the line, dont wanna break anything just yet.... but i gues i'll start with 20 psi for the tire pressure and see how she hooks
 

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Is GS400 rear end as strong as stock supra rear end?

If you have skinny's I'd start with rear tire pressure at 13psi cold and continue to bring it down towards 10psi hot as you feel comfortable. They are 26in slicks so they will feel a lot more stable than 28's on the big end. I'd set the two step @ at least 16psi... Probably a little higher.

If car bogs bring boost and rpms up on the two step.

Keep bringing the launch up till it blows the tires off... then it's too high.

I had stock rear end and driveshaft. They lasted plenty of 1.5's and 1.4 60ft's but as soon as the car started going 1.3's they broke. However, I was on 28in ET Drags. I dont think you'll be able to leave as hard on the 26 ET streets.

-Clark
 

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WI-FI FTW, GTFO fuse box!
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8,108 Posts
Start at 18-15 cold in the tires. What drishaft? If its stock you can still break it. I pretzled mine at a bar on the 2step so it can happen. The difference is I was on a 28x11.5x16 et street at 13psi in the tires. 8psi on the 2step will not be enough,waste of time. What clutch? Don't slip it too much or it will end up being a bad day. I have the wotm single disk and its great as long as its not slipped. Just a alight 'blip.'
 

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2JZ NA-T
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5,413 Posts
Discussion Starter #7
im using the SPEC stage III unsprung single disk.

the driveshaft is the TT 6spd fronthalf, TT auto rear half combo.

im sure the gs400 is not as strong as the TT 6spd, but more along the lines of the tt auto one.

im affraid of leaving the line at 16psi....but would anthing from 10-12 be enough? and could any one shine any light on the actual numbers for the 2step settings? right now i cant just sit on the throtle, b/c it seems like it'l build in upwards of 20 psi,

how can i set it to hold a consistent 12psi maybe?
 

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NA/T aficionado
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303 Posts
For the 2step try running less ignition retard, that should help. You need to know what wastegate spring you have too, normally without a lot of 2step parameter toying you won't be able to run less boost then what the spring designates the minimum boost to be at. Dont be afraid to leave at higher boost, you'll just spin. Work from there and move down until it hooks without bogging.....but you'll want some tire slippage for the best times.
As for the rear.....you won't break it.
 

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8 sec supra chick!
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2,753 Posts
Hope its not a daily driver because if you hook at all say bye to the driveshaft and possibly the diff. I wouldn't run without an upgraded driveshaft and trd dif in a 6 speed supra.
 

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2JZ NA-T
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5,413 Posts
Discussion Starter #10
yea im not concerned about the rear end too much. as far as the driveshaft, i gues we'll just see what happens to it.

and you're right about the launch psi, i would rather builds 16 psi (thats what spring i have int here anyways) and spin too much rather then bog or hook TOO well.

and thanks for the input Jessica....i just hope you're wrong :) no offense
 

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2JZ NA-T
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5,413 Posts
Discussion Starter #11
yea im not concerned about the rear end too much. as far as the driveshaft, i gues we'll just see what happens to it.

and you're right about the launch psi, i would rather builds 16 psi (thats what spring i have int here anyways) and spin too much rather then bog or hook TOO well.

and thanks for the input Jessica....i just hope you're wrong :) no offense
 

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8 sec supra chick!
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I hope im wrong too :) I break the stockers the first time out though.. Also I run about 10.75 psi in my tires and check it after each pass...
 

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2JZ NA-T
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5,413 Posts
Discussion Starter #14
me? no im running my regular wheels with a 225 tire on the front.....dont have money for skinnies right now...


question, i have my stock 16in rims with really good tires on them, almost 100%....should i run those instead of the 18 inchers with Riken tires on them up front?
 

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I would not recommend running that tire without skinnies and bias ply tires up front, it is not worth risking your car.
 

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8 sec supra chick!
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Whew, yeah not a good set up at all. Might end up with more than just a broken driveshaft if you run like that. Not safe I don't care what anyone thinks.
 

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w/out a skinny up front you mean? can you guys elaborate on exactly why/how?
it's not recommended to mix and match radial/bias ply tires. since the et streets are bias ply, you need bias ply skinnies on the front. some people will run with regular radials up front but you better be on your toes and on top of it. The ET streets have a very weird swaying feeling (feels like the car is moving side to side or floating) and with a radial tire up front if you correct too much/too quickly it can be ugly. With a bias ply skinny up front it will help the car track straighter and when you do have to make minor adjustments the skinnier tires aren't going to move the car as much because they have a softer sidewall and will allow the entire car to remain moving back and forth (if that makes sense?). The sidewall is too stiff on a radial tire is basically what it comes down to and the faster you go the worse it will get. I agree with some of the others, personally, I wouldn't risk running with radials on the front.

I start with about 18 psi (cold) in my ET Streets and go down from there.
 

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2JZ NA-T
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5,413 Posts
Discussion Starter #20
oo ok, that makes plenty of sense, just never thought about it that way. thank you for the input.

Now how skinny is skinny? b/c i also have the set of factory 16" front wheel laying around, i belive thats an 8.5 in rim?? could i get a bias ply tire for that size wheel and be safe? i really dont think my car will see aything lower that a 12s pass, i will be the more then happy if i can see an 11.999999 , lol, but i really dont think it will....

thank you for the input.


so i decide to risk running this combo i just need to really ease into it the first few passes to get a feel for the car, im not trying to be cocky but i have a pretty good sense of how to control a car that is going into a slide, been there more then enough times with wet road conditions and what not......and now i know that it will be much different going in a straight line with a realy soft sidewall down the track...but i do greatly appreciate all the input
 
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