Newbie with a stupid question

[Jas89TTA]

I just got my 89 TTA and not familar with turbo cars, My question is when I get on the car and it boosts up the car moves and let off the gas to slow down the turbo makes a noise it sounds like something flaping, I was told by someone that they thought it was the wastegate letting the air out Is this normal? I just want to make sure. Thanks, Jason

 

[OKTurbo]

Perfectly normal....

What happens is that when you're under boost and you let off the throttle, the throttle body butterfly closes....well everything from the turbo outlet...thru the intercooler is still charged up with 15 psi of boost. The throttle is now closed and the pressure has to go somewhere....so it goes back into the turbo.

This isn't necessarily a good thing, but at moderate boost levels it's just fine and very normal.

The wastegate controls the max amount of boost the turbo will make. The WG is located on the turbine (exhaust) side of the turbo.

There is another device you can add on the compressor side called a blow-off valve which will eliminate this "problem". (It's not really a problem until you pushing a lot of boost with a bigger turbo)

John