so i have an fd. the motor has around 1000 miles, streetported with 2mm seals. the car had a microtech ecu, greddy 2 row, catback, downpipe, 850/1600s, aeromotive fpr, and supra fuel pump. the stock turbos went while tuning. so the shop who was working on the car peiced together a t04s kit for me. i dont know the specs of the turbo, just that they used their own manifold, made a downpipe and new ic pipe, and used a tial wastegate and blow off valve. we dynoed the car and it made 354rwhp at 14psi. the car made 300rwhp at 12 on the stockers. so i wasnt really impressed with these new numbers. i dont know what happened to the dyno sheet from the single run. but anyway the car doesnt feel all that fast. i mean when it makes full boost its a real kick in the pants, but the twins pulled like there was no tomorow especially down low. this t04s makes full boost around 4.5K which seems pretty laggy to me. i thought this turbo was somewhat on the small side for an fd in comparison to something like a t78. so i was hoping for less lag than i am experiencing.

here are my questions. does this seem laggy for a t04s? does my power seem low? am i being greedy wanting 400hp with this thing? keep in mind i am still running the stock cat. i plan to go with a high flow soon. also if anyone has this turbo in the tri state area and wants to let me bring my car over and give me a ride in their's you can drive mine and tell me what you think. thanks for any replies.

steve

 

It's slow?! Are you talking about boost creep?

 

no. did you read?

 

Oh course it's going to be laggy compared to the stock twin Hitachis. It is after all, a TO4S. Do you have a picture of your setup?

 

Still running the stock catalytic converter? My guess is that would hold you back quite a bit on power (maybe even 30-40) and also make boost build slower as well.

 

heres some http://www.steveprew.com/engine/

 

30-40 what? Horsepower, kW? That can't be right, but perhaps a high-flow cat might help reduce backpressure. Perhaps your turbo is feeling laggy due to the backpressure the stock cat creates. What is your exhaust piping diameter? Having too big an exhaust system could also be the culprit.

 

My SR stage II spools a little faster than that! I too would throw on atleast a high flow cat. If you can get away with it, I'd put on a resonated mid pipe.

Also, is the manifold divided or not? CJ

 

Your #'s are pretty low. You should have about 350rwhp at only 10psi. 1badd7's To4s gets full boost (20psi) at 4000rpms

 

my t78 hits 16psi before 4500, so i'd say something is up

 

You spool is slow and your hp numbers are low. I suspect its either manifold design, not effiecient enough exhaust or both. 3" MINIMUM from the turbo back straight through would fix spool and power. Preferably a 3.5" would be even better. A fully divided manifold with a divided turbine will decrease spool time as well if your running a collected manifold and open valute turbine. but even with the open valute turbine your numbers are still low.

~Mike...............

 

well when the shop first gave me the car back i coulda sworn it was making full boost at like 3500rpm. then when i was pullin out of rotorfest like an ******* i floored it in first, nailed second and something happened. ever since then it hasnt been making full boost until 4500rpm like i said before. i brought it to the shop a few times and told them what happened but they told me that it never spooled any earlier than 4500rpm. i know this thing is capable of spooling sooner, i dont really care about the power as much as the lag. what are some things that could have happened that day to make it lag more now? also the wastegate has gotten stuck open a few times since all this, sometimes for more than a half hour until it closed again. thanks.

steve

 

I'm not a big fan of the 2 90 degree bends in your IC piping. On the stock cat, are you sure it may not be clogged? Go spend $100 and get a midpipe to test with.

I don't know much about the microtech ECU but are you sure its tuned properly? As others have said you should be able to put down 360rwhp+ at 10psi on T04S.

 

those are very low #'s for 14psi on a t04s

 

I think you answered your own question.

I would say it's in the wastegate. If it is sticking open boost will build slowly because exhaust is bypassing the turbo.

I went through this on my car.

It must be fully closed until opened by the spring pressure/boost controller.

 

this is what i thought too. i had them look at it, they said it was fine. it shouldnt be lettering at any exhaust at idle correct? i will check it out tomorow after work.
also i would get the midpipe, but i have the most obnoxious catback available (dual n1). i cant imagine the car any louder. i am working on getting a new catback so that i can run the midpipe.

steve

 

Nope, no exhaust at idle at all should bleed past the wastegate valve. What pound spring is in there? I am assuming that the wastegate is a poppet style? If so it is like a piston car valve. It should be seated tightly as to not let any exhaust past until the spring pressure is reached. You boost controller will counteract the spring by pushing boost against the opposite chamber in the gate. Check all that out first before blaming the manifold design.

 

With all due respect to the good advice given, nobody has asked for the specs on the turbo, virtually everything you are talking about is dependent on that. What trim, Ar, and compressor? That power level, and boost curve is similar to my T66 when I had a 1/4 hole in the exhaust manifold. a 1.32 ar could easily spool that slow, and would not start being in its sweet spot until 20+ psi, any other problems like those suggested would make that even worse. So all that has been said is valid for a .96 or smaller, but all bets are off if you have a larger hotside. Carl

 

The stock cat is what is killing you. Run a MP and when inspection time comes (if you have to) put the cat back in.

That is what I do here in Houston.

 

Ditch the cat.

 

yea i'm gonna ditch the cat. i know there is a problem though, because something changed.

so i jacked up the car tonight. turned it on, went under. the wastegate is letting out exhaust at idle. is this normal at all, or is something definately wrong there?

also is there any way i can find out the size, trim of the turbo by looking at it?

thanks.

steve

 

the wastegate shouldn't let out *anything* untill you are building boost.

ask the shop what turbo they put on. As far as I know, their is no way to tell the a/r by looking at the housing.

I would honestly go to another shop...leaving the wastegate cracked open like that is a really bad sign...

 

[QUOTE=Mark'sMazda]

ask the shop what turbo they put on. As far as I know, their is no way to tell the a/r by looking at the housing.



[QUOTE]


Some turbo's, i.e. some of the off-the-shelf garrett/master power/etc turbo's will list the a/r for the compressor housing on the front, there is usually a number for a/r on the back of the hotside too(side where dp meets). The a/r on the hotside will sometimes tell you if it's divided or undivided if it's one of the conventional a/r's that's used alot. If all else fails and the shop doesn't know/remember(don't see how they couldn't since I'm sure they charged you for it), then look for a serial number of any sort. Another thing to ask is wheel trim if they know or any other info.

I think there is more info from the shop needed about what you have on this to diagnose this but I'll also agree that the stock main cat is probably an issue as well as the wastegate might be. Honestly not experianced enough in wastegates to tell you what's right though.

 

yeah, something is definitely wrong with your wg if it's bleeding exhaust at idle. Replace that, also you need a wide open exhaust to take advantage of the turbo.

My T04S set up sees full boost at 3300 rpm in top gear, 390 rwhp at 12.5 psi and 402 rwhp at 13.5 psi with Extremely good mid-range torque.

Good luck,

Fred
94 Single FD

 

thanks for the reply. that power and response sounds awesome.

steve