What is a BOV (Blow off Valve)?

What does it do?

What is that cool sound i keep reading about in the posts?

 

It is to reduce excess pressure on forced induction cars I believe.

 

If the throttle plate is closed while engine is making boost, the compressed air will return to the compressor housing which causes "compressor surge" and also damages the turbine shaft. In the same condition, a Blow Off Valve will release the compressed air from the charge pipe to protect the turbocharger/supercharger from the pressure spike and also gives quicker boost recovery. By modifying the vacuum line routing, it can also be used as a relief valve.

 

i guess...there is no use for it for N/A =\ i like that sound hehe..