Basically the same thing. The difference is what they do with their "waste" boost. A blow off valve dumps it's boost into the atmosphere. Giving that familiar sound. A wastegate dump's it's boost into the exhaust system quietly doing the same thing.
Wastegate vents exhaust gasses to controll boost levels while bov's vent compressed air once the throttle body snaps shut. They both vent air or exhaust...but there purposes are quite different.
I was under the impression that a wastegate vents hot gas back into the intake....at least that's what it does on an SRT-4. Might be wrong but that's what I've heard.
The wastegate limits boost pressure and the blow off valve prevents the turbo from "stalling" when the throttle is rapidly closed under boost conditions. The waste gate directs exhaust flow away from the turbo inlet into the exhaust system downstream of the turbo. The BOV vents boost presssure to the atmosphere. It is installed between the turbo outlet and the intake system.
We did not use a BOV on our Bonneville car because it was wide open for the five miles and if you jumped out of the throttle it was because you were crashing in which case the turbo stall was a non problem.
Howard
alright guys some of you are way off here. They are completely different. The wastegate diverts exhaust gas from the turbo so it doesn't spin any faster or make any more boost. A BOV just vents off INTAKE air that would rush back into the turbo when the throttle blade is closed.
PS for anything turbo go to www.turbomustangs.com please. Im sorry but this place has a large lack of knowledge compared to there. That place has some serious dudes on there.
alright guys some of you are way off here. They are completely different. The wastegate diverts exhaust gas from the turbo so it doesn't spin any faster or make any more boost. A BOV just vents off INTAKE air that would rush back into the turbo when the throttle blade is closed.
The BOV gives you the distinct "psshhh" sound. This is because the compressed/boosted air is being released via a valve when the throttle body shuts. Because when the TB shuts, the air has to go somewhere as it is being forced in.
A BOV doesnt need to atmospherically vent, it can be used as a bypass valve which recirculates the boosted air back into the intake before the turbo/supercharger. Unless you are using a blowthrough MAF, you have to recirc. the boosted air back into the system on a Mustang because its already been metered.