low boost

[87supraturbo19]

ok i have 2.5in exaust and intake. i cant seem to get my car to boost over 5psi in 2 gear . so i shimmed the wastegate with 4mm i think. i thought maybe the spring was weak. i didnt really do anything, until i got into third then it went to 8 psi. i read that you dont always build full boost till second gear but i cant get it too. ?

 

[starscream5000]

I've got a 3" exhast (well half one, stops at the test pipe) and i boost really fast and hard (stock psi for now). My car came with the pacesetter catback (2.5") and I couldn't spool for shit when I put it on (that's why I've just got half of one right now.
I'd say your problem is in the piping size itself. GET RID OF THE STOCK TURBO ELBOW. Once that's done, BAM! big power difference. On turbo cars, the bigger the exhaust the better.

 

[87supraturbo19]

ok i take it back it only goes to seven psi. my car runs perfect. could it still be a small boost leak?

 

[87supraturbo19]

anyone, 4mm shim and only 7psi. any suggestions?

 

[xXxICExXx]

anyone, 4mm shim and only 7psi. any suggestions?

sounds correct to me...my car was 8psi with an 8mm shim when it was all stock. You cant get more than a couple psi gain by shimming the wastegate.

 

[87supraturbo19]

not saying this has anything to do with it but, before i switched turbos i was running a solid seven with the shims.

 

[xXxICExXx]

what was your reason for switching turbos? Just replacing with the same one?

 

[87supraturbo19]

if this adds any help my car pulls hard in mid range but seems to lose power in higher rpms. my clutch brand new.

 

[87supraturbo19]

i had it rebuilt by a certain person and when i put in on after about a day or two in started whining and the bearings were shot. so i bought a used turbo to put on because i wasted so much money on the rebuild.

 

[xXxICExXx]

hmmmmmmm.....can you take a picture of your engine bay? My car used to do that and its because the guy that rebuilt my car last year connected two vacuum lines in the wrong place.:nono:

 

[87supraturbo19]

sorry i cant. but i am pretty sure they are all connected correctly.

 

[87supraturbo19]

anyone?

 

[bigaaron]

With 2.5" exhaust, stock turbo, and stock elbow you probably should not run any more boost then 7psi, and shimming the wg is ghetto. You might have a boost leak.

 

[87supraturbo19]

thank you i geuss. i have a wife and a kid so i am broke. i just done it to see if it was the wg. i do anything i can to fix and keep my car. i just knew 7 was lower than what i was running without the shims. i guess i will swith back to my other wg.

 

[bigaaron]

i have a wife and a kid so i am broke.

Even better reason not to increase the boost, just keep it where it is and drive it. When you start increasing the boost is when bad things happen. 7 psi is totally normal. If you are reading the stock boost gauge then that could be the problem, the stock one is sooooo slow.

 

[87supraturbo19]

like i said i wasnt doing it to increase the boost higher than stock i just couldnt get it to read the stock psi without shimming it. i dont even have the shims in there anymore. i just want to know what is causing me not to have normal boost.

 

[bigaaron]

like i said i wasnt doing it to increase the boost higher than stock i just couldnt get it to read the stock psi without shimming it. i dont even have the shims in there anymore. i just want to know what is causing me not to have normal boost.

Possibilities:

Boost leak
Turbo on the way out
Clogged cat
Gauge wrong
Wastegate spring weak

 

[87supraturbo19]

Wastegate spring weak- thats what i was trying to eliminate with the shims.
Clogged cat-new cat
Turbo on the way out-used turbo possibility
Boost leak- good chance

thanks man

 

[87supraturbo19]

alright at about 5500 to 6000 my car has a slight stutter in it. would this probably be a boost leak.

 

[starscream5000]

I believe your car should fall off on power in the upper rpms due to the restrictive stock ic piping and intercooler. Get those bottlenecks out and that should clear up the loss of power up top.