jetfire76

ok...i went out on another test drive to try to solve my boost problems. same story.
i boost to about 8 psi at 5500rpm then it slowly starts to drop to about 5psi by 7000rpm. i was testing in 2nd and 3rd gear. i tried 4th and it got to 8psi but was dropping a bit as i got to 6500rpm. i then shifted to 5th but when i started to creep up to 120mph i backed off since my wipers started moving from the wind resistance. the odd thing is it was a slower creep to 120mph than i expected. anyway, the main issue here is what i think is low boost.

i wont list all my mods but the ones pertaining to power are: rebuilt S5 turbo and manifold(i've only put about 300 miles on it since the rebuild), FCD, 3" DP that reaches to the stock cat back, 3" custom TID into K&N cone filter, Halman MBC(lowest setting). also my airpump and ACV are removed. my boost gauge is autometer is that makes a difference. going by the other stock gauges my oil pressure seems pretty stable only going to about 90 under hard pulls, my coolant temps have been a rock solid 1/4 since i flushed and filled.

i checked for any vaccuum leaks and can't seem to find any. i'm thinking it might be the wastegate but i see no reason why it would not be working properly considering everything had been rebuilt. help is appreciated. thanks!

-jet-

S2-13BT

Check this out for a few ideas.

http://ausrotary.dntinternet.com/for...ic.php?t=12667

a7r

You might try pressurizing your intake system (i.e. from the turbo inlet back). Take it to a bar (15 PSI), and see what happens. I found a bunch of problems with my intake system only after simulating boost and noticing where air was leaking.

jetfire76

hmmm...thanks. i'll check that out. i'm prolly gonna try putting the stock TID back on and removing the MBC and see what happens. i am starting to think i have some sort of obstacle in the stock Y-pipe and/or mufflers since they are 14yrs old and rusty. as far as the boost drop, i still have to check the wastegate and leaks again...