Odd sound under boost

[TType85]

Had the car out this weekend for the Bates car show. On the way there the car ran fine, only had one issue where I forgot to turn down the RJC boost valve when I put everything back together.

(side note: Bison built TA6262 MFS turbo will do -14hg of vac to 28psi in 1 second according to the power logger from a 70mph roll )

On the way back from the show, about 30 miles out I started hearing what sounded like a supercharger any time I would go above 5psi. The car would boost to 20-22 then drop down to 15. No knock, ~820mv on the o2. Other than that the car drove without issues.

My first thought was the hose clamps so I pulled off and checked the clamps and they were all secure.

Tonight I pulled the IC and the hoses and I don't see any holes in them but the turbo to IC hose seems like it may have a few nicks in it but nothing that goes through and that looked like it would cause the sound. I am going to put a new ones on just in case though.

I checked the turbo, pulled both the intake and exhaust side. No play, no damage so it's good.

What else should I check? Any ideas?

Car mods are TA6262MFS, CAS v4, 55# inj, TT chip, ATR 2.5" DP, 3200 stall converter, racetronix 340lph pump, custom CAI with LT1 MAF and MAF translator.

 

[V6sleeper]

Check for a cracked header or separation in the exhaust in the turbo area, was the down pipe loose? sometimes the dp bolts loosen up and cause boost issues.

 

[TType85]

Check for a cracked header or separation in the exhaust in the turbo area, was the down pipe loose? sometimes the dp bolts loosen up and cause boost issues.

Headers are good, no leaks. Downpipe was tight too. I'm hoping it's the 2-2.5 step hose between the turbo and ic. Going to replace all 3 hoses just in case.

 

[aminga]

Verify oil supply to turbo?

 

[TType85]

Verify oil supply to turbo?

I'll check that tonight, oil pressure for the motor has been good (~20psi hot idle). Last turbo I had make a strange noise was a DBB PTE that had issues in the center section.

 

[TType85]

Called RJC and have all new hoses an clamps are on the way.

 

[Heskahoka]

Maybe not the turbo? I had a bearing start to go on a tensioner pulley on my G35. Sounded exactly like a supercharger whine at certain RPMs.
Made my car sound pretty cool until it locked up and smoked the belt.

 

[TType85]

Found the issue. Was putting on the new hoses and clamps on the throttle body and it moved. Somehow the bolts must have backed out. Tightened them up and put it back together. Going to test drive it tomorrow time permitting.