Why do performance turbos make that sound?
 

I have noticed from watching a few videos that the high end turbos make a noise when the boost drops, why??

Does no one know??

do you mean the sound of the blow-off valve? that is the pressure being released to prevent the turbo from overboosting. this often happens between gear changes as the RPMs drop from gear to gear. you don't want to keep the turbine boosting and boosting and boosting else it will blow up.

OOOOOHHH, ok thanks for the info.

there is a difference between a diverter and blowoff value.

yes, a diverter re-routes the air after the compressor usually back into the inlet of the compressor. Blowoff valve is blown into the atmosphere

is one better than the other?

Depends on the application...:smilie_th

there are two basic types of Blow off Valves (BOV's

Vent to Atmosphere (VTA)

and

Vent to Intake (Sometimes VTI)


VTA gets that ricey sound often found in movies. VTI is not very good with stock intakes and stock air metering devices. They tend to work better with stand alone ecu's or a properly functioning speed density air sensor

All blow off valves make a sound, usually with stock intakes it is masked, but even a VTI will make a noise that is audible in the cockpit if there is a CAI or ram air intake fitted to the car.

I hope that helps

Some of the cool sounding cars are running with out a BOV or recirc valves. That gives that chatter sound or the compressor surge of air being forced backwards through the intake system.
Like in this video.
http://www.youtube.com/watch?v=SX0Z9...eature=related