QwkTrip

iTrader: (23)

I have a Nick Williams 102mm cable throttle body on a wet sump H/C/I LS7. Drilled a 1/8" hole in the blade to get enough base air flow at idle. I often times hear a whistle noise, like a turbo blow-off valve, when I let off the throttle at high rpm. Trying to decide whether this is from the crankcase, or just noise from the throttle body. Anybody else experience noises like that?

I'm thinking it's the throttle body. I don't have any oil seeping out the air filter on the valve cover that would indicate a lot of crankcase pressure. Almost bought myself a vacuum pump but it costs sooooo much money that I'd like to better convince myself that it's necessary before taking that jump.

Che70velle

iTrader: (6)

I hear the same noise from mine. It’s currently undrilled, but that may change in the future. I built my own carbon fiber air intake, and put the filter behind a close out panel, actually inside the drivers fender. I can hear mine “whistle” going onto, or off of the throttle at certain low rpm’s. I only hear mine do this when the drivers window is down.

Darth_V8r

iTrader: (4)

It is the iac solenoid. At wot it opens way up and you hear the whistle

Russ K

iTrader: (1)

Is your clean air side pcv hooked up to the air bridge?

Russ Kemp

Che70velle

iTrader: (6)

I don’t run a pvc setup, or have an IAC valve and mine makes the “blow off valve whistle”...

QwkTrip

iTrader: (23)

I don't know what you mean by air bridge?

I have LS7 valley cover and valve covers. Valley cover is plumbed to intake manifold like an LS1, LS2, LS3 would be.
Passenger side valve cover has an air filter on the vent tube. Driver side valve cover is capped.

I had to use an air filter on the valve cover because the throttle cable blocks access to the clean air port at throttle body. Shouldn't make any difference, it's all just ambient filtered air either way.