whats up...
i am gettign very confused with the whole BOV thing..i have an HKS SS but it was on the supra when i got it...what i am wondering is if i want to change it do i have to buy just the BOV or do i have to buy the whole kit...what is the difference...and my friend just bought an HKS SS for his evolution...i thought that the BOV's just replace the stock BOV and go in the same spot...a shop installed it for him who works with alot of high hp turbo cars and they welded it onto the stock piping with a flange..and left the stock BOV in its spot as well...how can this work and is this the right thing to do...also is the BOV supposed to be mounted before or after the turboes...thats a really stupid question but i could have sworn i saw a car with the BOV mounted right after the intake and not after the turbo...IDK everytime i look at a diffedrent car i get more confused...also are some BOV's not compatable with some cars and can they make you loose performance and how?? just please someone answer as many of these stupid questions as possible..i need to be cleared up on this...and i did a search and found nothing BTW...ok thanks
icedsupra

Red 1994 Supra Twin Turbo 6 Speed
BPU

"You know you can't keep up"

Ok, why are you replacing the BOV? If its broken, just get a new BOV and put it where it previously was. If you just want a different one i have to ask why. The HKS SSQ is know as a top quality BOV, maybe the best for sub 20psi applications.

As for the stock location vs. welding to IC pipes, its really about preference. If you are still on the stock MAF and you are experienceing stalling problems it would probably be a good idea to weld it to an IC pipe. The reason people keep their stock BOVs is because the air that is blown off of the stock valve is recirculated into the intake. The stock MAF system, expects to see that air re-enter the system and therefore adds more fuel. If you have an open atmosphere BOV, the air never gets recirculated and your car goes rich. Get it?

Also, I have never heard of a BOV not being compatable. Plus they don't make you lose performance unless they are leaking boost. And as was said previously, the BOV goes between the turbo and TB. How would a BOV work if it was before the turbo? Would it blow off air that wasn't compressed? Just think about how the system actually functions and it will make more sense.

BOVs leak when they are not functioning properly of like Ryan said, the spring is set too soft.

As for the kits, each kit made to fit in the stock location is different for each car. Each BOV flange is specific to only the BOV(s) it was made for. And as Ryan said, many BOVs offer options for recirculation. That is probably why the EVOs don't run well, the air is not being recirculated. read my previous post again and you will understand why that is bad.