will i lose power???

[bersh240]

story time.so i was driving home from work at 1 am roads are always empty.so i had a lil fun and noticed that my car seems to pull harder at 3/4 throttle when boost is around 10 psi than at full throttle at 14 psi.ive read that a t25/t28 turbo is only good till about 13-14 psi.so is it possible that with my set up that 10psi is ideal and that the 14 is just smacking my engine around? i dont wana turn down the boost if its gona take away alot of power but it seems i may gain a little if i back it off, plus i know 14 is pushin it on stock injectors...so could anyone be so kind as to set my brain on the right path?

oh if you people dont remember me its an sr turbostock injectors and such. just 255 fuel pump

[BACARDI_DWB]

what you are feeling is the wastegate. at 10psi the wastegate is most likely closed and your not loosing any power.

but at 14psi your wastegate may be cracked open and your exhaust is going thru your wastegate, not your turbo.

keep it at where it is, your car is fine.

[bersh240]

learn smthin new everyday.thankyou sir

[ca18detgabby]

are you tuned for that kind of Psi?

IIRC the stock fuel system is best suited for 12PSI.... but idk.

you could just back it down to 12PSI and see how it goes, whats the worst that can happen? you loose a bit and change it back......

[float_6969]

There's a big difference between a T25 and a T28. Which are you using? What mods do you have? I could be that you're running lean at the higher boost pressures and loosing power. It could also be that you're getting detonation at the higher boost pressures and the ECU is pulling timing. You'd never hear it because the ECU will pick it up way before your ear can and pull the timing back.

[Danski]

what you are feeling is the wastegate. at 10psi the wastegate is most likely closed and your not loosing any power.

but at 14psi your wastegate may be cracked open and your exhaust is going thru your wastegate, not your turbo.

keep it at where it is, your car is fine.

Unlearn this, its completely wrong.

[BACARDI_DWB]

Danski,

if you think that it is wrong then please explain to me the correct answer, its easy to say something, but i would like to see you back up your reason for it to be wrong.

A wastegate is there to bleed off exhaust gasses that the turbo can not take without surging, it will do so at a specified boost level, and then progress to open further to let more exhaust go thru as the boost gets higher to maintain a certain PSI. if you look at any turbo dyno or listen, you can feel the surge of power while the wastegate is closed and once it opens, you can hear a difference and feel a difference in power. I highly recommend you read Corky Bell's book Maximum Boost, if you are unfamiliar with how a turbo system works.

Please don't come in a forum, say something is wrong without giving your explanation of why you think it is wrong. I am happy to say that I am wrong if someone presents a better case, but by judging your post, I don't have much to learn from you so far.

I would also have to agree with Float, he has an excellent point that it may be timing...

[bersh240]

im honestly not sure if its a t28 or t25.its bb tho so i think its t28.i cant read the numbers on it so idk how to tell.

im gona back it down to 12 and see how it goes.i think im leaning out like float said.i have a n62 maf and 450cc injectors im gona throw in when i have money for a tune..

and if my ecu is correcting timeing due to detontation could that cause the car to jerk while at full throttle? like stop accelerating then start again? cause the guys around here think its a trans sensor problem. but i think it may be related to this.

[BACARDI_DWB]

What RPM is it jerking at? does it give any noise when it jerks? if you are on a T28 and 14psi then you are most likely leaning out. explain the jerk please

[bersh240]

like 5k rpm mabey.car seems to stumble.mabey fuel cut due to ecu thinking everythings about to explode?

[BACARDI_DWB]

when you back the boost down does the stumble go away? if it does then you know what the problem is.

[bersh240]

ya im gona try that later today.i have to go put my interior back together first so i have a seat to sit in tho.

[CakeEater]

If your still using the stock MAF then you are hitting the boost cut for it and that's what is causing the jerk.

14 psi is right around where most stock CA MAF die out at. I've hit a couple times by setting the boost controller just a little too high.

[Ca_Silvia]

If your still using the stock MAF then you are hitting the boost cut for it and that's what is causing the jerk.

14 psi is right around where most stock CA MAF die out at. I've hit a couple times by setting the boost controller just a little too high.

My car PRE-TUNE did the exact same thing.