Somone that knows a thing or 2 about turbos on cars

[Christine]

Ive watched some vids and im wondering what makes the swosh swosh swosh sound on the turbo when the air realses is it the bov or the wastegate?

[Rocko9]

swosh swosh swosh? The noise you are hearing is the impeller being spun by exhaust gas, and air being sucked in by the impeller.

[Christine]

well ive heard the normal bov sound but this one starts off loud and goes into a quiter and quiet'r sound like a 3 sound bov found a couple videos of a single bov sound and then one that blows out into a 3sound

[Afrospinach]

The sort of multi stage sound is turbo flutter from compressor surge. It happens when you let off the throttle lightly and there is not enough pressure to keep the valve open AFAIK so it opens intermittently as pressure builds. I just cannot find a good vid to confirm this is what you are talking about.

Wastegates open so you don't overboost and are usually a constant sound while you are pedal to the metal, if you have a dump pipe it will make your favorite machine sound like a tractor. Yay. My friends love these things especially when they are not plumbed back into the exhaust(which is usually illegal) and I really don't get it.


edit:
http://www.youtube.com/watch?v=Um9DUyUrtaE

there you go, there is also a related video called BOV myths busted, which will probably tell you that I am talking a load of shit :P but it is too long for me to watch.

[Rocko9]

well ive heard the normal bov sound but this one starts off loud and goes into a quiter and quiet'r sound like a 3 sound bov found a couple videos of a single bov sound and then one that blows out into a 3sound

It's probable that the driver floored it at the start then let off. In that case, the turbo is spooling down. Listen to other pneumatic tools, they also spool up and down.