My Friend let me have a adjustable wastegate, so i put it on and cranked it up from 12 to 15psi to see how it felt, and after 5000rpms, the engine will surge and have some really bad clacking noise. my car is stock, do you think this is the valve springs, am i floating the valves, will it hurt my engine? I figure it is the valves and plan to replace them and the springs, what kind do you all suggest?
if you need to know the 2 times i tried it i pulled 11.7 and 27 degrees of knock
Thanks for any advice-Jon
Jonathan,
The factory tachs are known to be, well not too accurate. At WOT, mine reads anything past 3400rpm(as reported by TurboLink) as 6000+, all red.
New valvesprings may be a good idea but I doubt they are the problem you are talking about, the really bad clacking noise and the car surging is the computer pulling out boost because you are experiencing severe knock. You need to turn the boost back down before you blow a headgasket. You don't want to see more than a few(2-3) degrees of knock, and that's usually on a shift. You're really lucky you didn't damage your motor with 27 degrees of knock.
My advice is to turn down the boost, back where it was and then try to tune from there. You want to get as little knock as possible. Watch your O2 values, try to shoot for around 780 and watch the knock. You could try higher octane gas, which should help as well. Good luck
