well, since ive just recently caught myself in a huge confusion about how they function, and im pretty sure there are other people on this forum who are in the same position but would rather remain anonymous, ive decided to ask you guys, pretty much known for your turbocharged beasts, how a blow off valve works, etc. Thanks in advance

 

bov: it's a vacuum actuated valve that opens when there is vacuum present in the intake manifold (as opposed to pressure). this scenario is present when the throttle is closed (i.e. at idle)...so, that's why every time someone shifts (closes throttle, and disengages clutch) the bov "blows off". it's that simple.