Turbo-charged

i started off with a 10psi spring. held 10 psi perfect. cranked the boost up in baby steps up to 15psi (AVCR). above 15 psi the boost would drop, it might touch 16 but start dropping down. thought maybe it was the boost controller, threw on a manual boost controller and it did the same thing, only the boost dropped down to about 12 psi at 9k rpm.

at this point i thought maybe there was a leak somewhere and pressure tested the intake system to about 35psi via airhose. no leaks anywhere. figured it was the wastegate spring maybe being to small? threw in a 15 psi spring.

boost was dead nuts rock solid at 15 psi. turned the boost up to 18 and it was fine. turned the boost up to 21 psi, it hit 21 psi then dropped to about 13 psi REAL fast. after that boost would only go up to about 13psi, even when i completely dissconnected the wastegate all together (should have made an *** ton of boost).

im pretty damn confused now. its a brand new tial wastegate. the only thing i can think of is that i did not get the wastegate intended for race gas, however my last 35mm was not the race gas version either and i probably ran 50 gallons of racegas through it with no problems.

whats my next step at this point? bigger/differnt wastegate? is this just a defective wastegate? wastegate intended for race gas?

just for some more info.....manifold is a 4-1 tubular with the wastegate location right in the center of the front of the collector. turbo is a GT35R. boost contollers used are apexi AVCR and extreme MBC. precision 750hp IC with all aluminum charge piping. 3 inch downpipe and 3 inch exhaust.

thanks in advance for any imput.

tub_sephiroth

Bump. I'd like to know the solution to this problem also.