My boost creep theory:

[GoldT]

I posted in the turbo section a couple of weeks ago about my boost creep problem. I think I might have figured out the cause. My lifters/valvetrain have been getting noisier as time goes on. I've also noticed that my transmission(so I thought)was having trouble upshifting at full throttle. I think, instead, that my valves are floating due to weak valve springs(100k mi.). And I theorize that my intake is getting pressurized. I've tried using 2 different boost guages and I'm seeing 20-25 lbs. at WOT with very little detonation and not much power. So does that sound reasonable?

 

[Ormand]

No. It doesn't sound reasonable to me, anyway. Why would your intake get "pressurized"? If the valves are floating, usually exhaust valves go first, not sure if that's true with the GN cam or not. But the result is misfire, maybe backfiring, not more boost. Will certainly limit power. But the valve float won't occur until higher rpm than max boost, so knock and peak torque should occur BEFORE valve float. High boost without power, and without knock, can mean that the boost is not getting to the cylinders. Where is the boost gage connected? If it's to the doghouse, then it's reading the same boost the intake valves are seeing, but if it's to the turbo, then there could be a restriction in the IC, or maybe in the throttle body. Is the throttle opening all the way?