Ricter

what exactly does a blow off valve do? Does it come a stock FD, or is it a purely aftermarket part? Also I commonly hear turbo-charged cars making a hig pitched decompressing type noise whe they shift. is ths the BOV doing that or something else? If soething else then what?

Thanks for putting up with my stupid questions, and thanks to anyone that actually responds.

Richard

sc93rx7

A BOV acts to releve pressure when on boost and the throttle is released, this prevents compressor surge(which is when the on rushing air hits the closed throttle plate , and slows the turbines which could possibly lead to damage). Our cars don't come from the factory with BOV's, they do however come with bypass valves which do the same thing , only instead of releasing the air to the atmosphere it is plummed back into the intake. And finally yes the noise made by some turbo cars when the throttle is lifted is a BOV. Hope this helps.

PraxRX7

I replaced my Stock "BOV" or more appropriately "bypass valve" with the Apexi Dual chamber BOV...it isn't the best if all you want it for is sound =/ but I like it all the same. (Although I may be switching to the HKS racing BOV soon because the APEXI one doesn't fit in our cars to well.

Ricter

Are there any performance benefits toa BOV alone? or is it just used when you're running more boost than normal, ie upgraded turbos... etc.... how much of a challenge is installing a BOV?

Richard

mmaragos

Dude, unless the PSHHHHH sound is very important to you, go with other upgrades first. In most cases, you don't really need a blow off valve. Most are installed for the sound. And you could just remove the return to the air box...open it to atmosphere and it will make some noise.

PraxRX7

I noticed a bit of boost consitancy gain with my BOV, higher boost in lower gears as well as my BOV holds some pressure in order to release the BOV at any time necessary (keeps the turbo out of harms way a lot better than a cheap *** "bypass valve")

It is mostly a safety/sound feature though.

Hell I installed hte BOV kit initially only for the sound when I first bought my FC and had no idea what anything on it was...and so began the tinkering.

Flybye

The ONLY time a BOV would really be needed to be upgraded is when you are running higher boost pressures. The GOOD BOVs actually release pressure faster than our stock BOV, and this is important at higher pressures as you dont want that pressure kicking back at the turbos.

If you are talking about HP wise, they do NOTHING to give you more HP. It's more of a safety device than anything else.