Whats the max anyone has boosted on a stock EJ25 and stock 4eat?

[Andrew]

I'm wondering what the max boost the 4eat has seen. I've seen a couple 7psi people but anyone running 10+?

* Registered users of the site do not see these ads.

[NickSTi]

Joe Hogan is the man to talk to. I ran 7.4# in my 2000 with no tranny work (and no electronics).

[HRE | giulio]

adam bloom did over 20psi, didnt he?
though i think it broke the motor at 24#.

my memory isnt what it used to be though so i may be mistaken.
g

[8Complex]

giulio - I think he ran like 18, actually. But that was on a STi RA manual trans, not a US-spec auto.

I think Kevin Thomas would be the man to talk to about this one, though he was running on an EJ22 instead.

[Andrew]

oops, forogt bout the tranny forum. if this shoudl be moved, move it.

[oem]

12 psi is the max anyone should run on the stock EJ25 for racing, not even using it for daily-driving. all the blown engines are resulting from people pushing their boost too far. As for the tranny, gears can be broken on light boost. it all depends the driver. I drag raced my five speed gears at 10 psi and drove around for about two weeks and did not have any problems.

[Andrew]

well thats nice for your MT but I just want to know the max someone has boosted on the Automatic 4EAT. I KNOW the MT can handle a fair amount of boost but everyone talks about the 4eat being stronger. well i want to know the boost limit at when things start to break down and what exaclty breaks down. is it that it just gets too hot? does the torque converter fail or something? what happens?

[NickSTi]

Like I was saying Andrew, Joe Hogan is the man to talk to. He has a EJ25 4EAT. As far as i know you need to do some work to the TC, maybe some more stuff.

[Legacy GTR]

Andrew,
If you can post your findings on that here that would be great. I'm wondering the same thing. I have almost all the parts for my turbo, wonding if/how soon i'm going to need trans parts.
Mike

[Joe Hogan]

It appears that the 4EAT can handle somewhere around 300-325 HP. When you push more than that the clutches begin to slip at the shift points. This is with very high line pressure and street tires. R tires would probably cause more slip.

This info was gathered with a Level 10 competition tranny, valve body and TC. We are on the third edition of the competition tranny. Most trouble has been with the TCU and the everyday grind of a daily driver.

When everything is working with this tranny it is very powerful. However the electronics are a bear.

Most people that race with this tranny use a MY98 or earlier. Rally Khight uses a MY98 4EAT with a manual shift valve body. Not something that can easily be lived with on the street .... though I have considered it:P

I'm going for broke [literally] with the 4EAT. Pat at Level 10 and I are close to getting it right. Then I can get back to making 400 HP with the Cobb motor in the car

[Kevin Thomas]

Originally posted by Joe Hogan
I'm going for broke [literally] with the 4EAT. Pat at Level 10 and I are close to getting it right. Then I can get back to making 400 HP with the Cobb motor in the car

Good lord! I must bown down to you! That's awesome! I don't count because I never ran about 5psi. I played with the manual boost controller but it was WAY too touchy and boost would immediately go up to 12psi and back.

I don't know what 5psi of boost and a 70 shot of nitrous is comparable to boost only but that's the highest I have gone (A big mistake but didn't notice the 70 shot nozzle until 2 bottles later and lots of unnatural burning metal smells coming from my engine bay).

[Andrew]

isnt 1psi equal to around 10hp. if thats true, then kevin you might have been pushing an equivalent of 12psi. but im probably wrong.

[NickSTi]

yeah as far as i know (reason it out) it wont equate like that. psi = lbs per square inch i.e. a pressure. so since nitrous is only adding oxygen and nitrogen (catalyst right?) to the air/fuel mixture you dont add the two together for a turbo/nitrous car.

unless you were equating it to psi needed for a turbo car to match the hp output of turbo/nitrous.

[Andrew]

unless you were equating it to psi needed for a turbo car to match the hp output of turbo/nitrous.

thats what i meant by what i said. im just trying to see when the tranny will blow hp/torque wise.

kevin, you were doing 70shots with or without the bottle warmer? IIRC once you put on the bottle warmer it shot the bottle PSI through the roof and lead to the failure of the tranny. or am i wrong?

[Kevin Thomas]

I didn't mean for you to put the two together. I was only running a 60 shot when the tranny went and the 60 shot was with a newly installed bottle warmer. I ran a 70 shot a few months back by mistake. Nothing happened bad. I just noticed odd metal scents coming from the engine bay.

On the other hand, I was wondering what the hp equivalent of pure boost was/is as compared to a 60 shot (with bottle warmer) and 5psi of boost from a Minnam turbokit. If somoene new the answer (Say 10psi of boost) then I am assuming you can say this is where you could expect your tranny to fail. Everyone's car is different and someone else's tranny may fair much better or worse but this could give you an estimate of sorts on where you can expect tranny failure (without a tranny cooler or any upgrades to your transmission).

[NickSTi]

well kevin you maybe are overlooking the easier comparison, instead of equating it to boost, equate it to hp. if with 5psi and a 70 shot you are getting peak 310 at 6krpm then your tranny may not last much longer.

but i have an interesting quesiton here: dont most good nitrous systems inject at WOT and stop when the throttle closes (come off the gas to shift? oops exclude the auto guy)? oh well since this is an auto related thread skip that wondering. cuz i was saying no nitrous off-throttle would drop your hp output down enuff to make it a less stressful shift.

[Kevin Thomas]

Originally posted by NickSTi
well kevin you maybe are overlooking the easier comparison, instead of equating it to boost, equate it to hp. if with 5psi and a 70 shot you are getting peak 310 at 6krpm then your tranny may not last much longer.

Good point Nick! Even with hp figures though....we need to know the torque at the point of breakage since torque is what kills the tranny. *getting dizzy* I'll let you guys figure this one out. I'll go drive now.

[Andrew]

if the problem is when it shifts and the clutches slip, then an EBC should work wonders. we could lighten the PSI as we get higher in the RPMS and around 6k drop it to around 5-6psi. that should help it shift better than at a flat 10psi. or am i wrong?

[NickSTi]

True kevin. That was what i meant... torque. just didnt say it

EBC? I do not understand how that helps the situation. I am not saying they do not exist (maybe the expensive fuzzy logic ones do this) but i do not know of any boost controller that tapers off boost at higher rpms. but when you think of it, this is not that hard of a feature to have in a boost controller so maybe they do exist.

The truth about our AWD tranny and high torque output is sometimes even stock cars get broken gears (some have this bad claim to fame like Danny). so tapering off the boost from 10psi to 5psi will help, but once the shift isnt smooth the shock may still kill your tranny.

Seems to be no cheap way around more power and bulletproof tranny. I think the auto guys are gonna have the best chance tho. shouldnt have jumped on the manual train. only if level 10 returned my emails!!!

[Andrew]

i thought all EBCs can tapper off boost. I KNOW the AVC-R can do it.

[Kevin Thomas]

Originally posted by Andrew
if the problem is when it shifts and the clutches slip, then an EBC should work wonders. we could lighten the PSI as we get higher in the RPMS and around 6k drop it to around 5-6psi. that should help it shift better than at a flat 10psi. or am i wrong?

If the problem is in fact when it shifts and the clutches slip, than an upgraded valve body is THE solution. In level 10's case, the Hydrosystem. Why I didn't mention this earlier I do not know but this is what Pat Barret of Level 10 told me all along (call him and ask). Maybe that's why I haven't had to hitchhike a ride home from the dragstrip yet since my tranny got rebuilt. I had my tranny rebuilt after I got the valve body job but my tranny was already going south. It still preserved it just long enough for some more racing.

Remember that Level 10 isn't the only game in town, just the most popular autotranny shop. A shop near me swears they can upgrade any autotranny valve body and torque convertor of a car that I bring in. I'm sure there are autotranny shops all around a good bit of us that we have not bothered to give a call. Keep the info coming.

[ImprezaRS dot com]

Mark Josetsky (he was "mjos" here) ran his AutoTranny turbo at 14 psi here at 6,000 feet a few times with no problems.

Joe at JC Sports bought the car when Mmark got a new S4 as a company car, and still has no trouble with the autotranny a year later, although he did blow the motor and dropped a 2.2L in it with 8.5:1 pistons and runs 7 psi now.

Larry

[Kevin Thomas]

Originally posted by ImprezaRS dot com
Mark Josetsky (he was "mjos" here) ran his AutoTranny turbo at 14 psi here at 6,000 feet a few times with no problems.

Joe at JC Sports bought the car when Mmark got a new S4 as a company car, and still has no trouble with the autotranny a year later, although he did blow the motor and dropped a 2.2L in it with 8.5:1 pistons and runs 7 psi now.

Larry

Here's Mark's old website: MJOS

[ImprezaRS dot com]

Wow, that was a slow turbo then, running a 14.6 @ 14 psi at 6,000 feet - my 5 speed got a 13.7 on only 3 cylinders and 8-10 psi at Bandimere

Larry