What are the performance aspects, if any, of a blow off valve? I’ve been thinking about it for awhile now and I can’t figure out any real useful purpose for it. Other than it sounds cool but not overly useful.
it prevents compressor surge, good way to make sure your turbo lasts
Yup… saves your turbo.
Also if your turbo doesn’t break first, the throttle plate can break off and get sucked into the engine.
What do you mean by compressor surge?
when the throttle plate is closing or closed and there is still boost being pumped toward it, and has no where to go but build up, therefore a blow off valve releases that.
Think of it this way. Imagine that you (turbo) are blowing through a straw (intake piping). When the end of the straw is uncovered (throttle open) everything flows fine. Now plug the end of the straw (close throttle) and all the sudden the air that you are blowing into the straw has nowhere to go. Pressure builds up and forces back against your lungs (turbo) unless that excess pressure is vented. Unfortunately when you force air back towards the turbo it causes it to stall and eventually spin backwards. This can be extremely hard on the bearings and the turbo impeller itself, just like continuing to try and blow into the straw with the end plugged isn’t very good for your brain cells.
If you don’t want your turbo to fail and break down faster than normal, don’t run a bov, if you don’t like the sound of a bov then recirculate it, that should cut down on sound. Either way it’s not smart, to not run a bov.
Think of it this way, turbo pressurizes the air between your turbo and throttle body, throttle body closes, air goes rushing back towards the turbo, and could cause the impeller to spin the other way, in otherwords, it’s bad. turbo spins one way, you don’t want it spinning the other way.
Whoever told you a bov isn’t needed or has no purpose probably needs to wear a hockey helmet when he/she goes out in public (to keep himself safe).
Awesome explaination…if you can’t figure it out now, just keep holding ur finger at one end of the straw and keep sucking
Most turbos, escpecially used ones have at least a tiny bit of play in them. And when all that pressure backs up against the turbine and cuases it to slow very quickly, that also causes it to vibrate. This damages the bushings or bearings and then causes more vibration…soon the vibration takes out the turbine blades or the bearings/bushings for good. The loose bushings/bearings can also alow enough play in the tubines to let them touch the sides of your housings, shooting flecks of metal into your engine. And then the whole turbine blades right behind that!!
Cool thanks for the explanations guys I get it now. I liked the one with the straw, lol made it easy to understand.
i did that and passed out, so if that happens to my car does that make it a sleeper??? 
[quote=“nis_mo”]
i did that and passed out, so if that happens to my car does that make it a sleeper??? :)[/quote]
yes the rims with stock suspension help the sleeper look come alive.
i did that and passed out, so if that happens to my car does that make it a sleeper??? :)[/quote]
yes the rims with stock suspension help the sleeper look come alive.[/quote]
i have coilovers sitting in my room now rob :finga: