bov+bpv, good idea or bad

[azn2nr]

i was having some trouble with surge on the 39 when i had it in. now though i have a rfl that is venting aptnophseric (sp) the only problem is that without a washer for adjustment it doesnt like to stay completly closed at idle.

my stock valve didnt work well enough to vent all of the pressurized air flowing thorugh the tubes and the rfl at low boost doesnt stay open long enough to vent completly causing verry little surge combined with the opening and closing sound of the piston being pushed open.

will having a stock vlave plumbed in right after the trubo suplementing the rfl work to alow full depressureization of the pipes without causing any harm one way or another? i think that it works in theroy but do you guys think it will in reality?

[BAC5.2]

Yea. I know of 1 WRX owner who ran 2 BOV's, and I have seen multiple Supra's doing it.

The WRX guy had an SARD just after the turbo outlet, and an HKS SSQV on the intercooler.

Sounded pretty bitchin. I will probably run the stock BPV right after the turbo outlet, and a different BOV off of the throttle body.

The atmos. BOV can then be set just for Higher boost, and the primary BOV should be able to handle lower boost settings.

[azn2nr]

sweet. its just the low boost thats givin me issues so i know that the stock one will be fine.

[BAC5.2]

Well, be warned. My stock one was opening under boost above 13psi.

I'm thinking about getting a stock one to use though, or maybe one from an EVO or something.

[vrg3]

Jason - Yeah, like Phil says, putting two in parallel is a common way to get more flow, so if you do it correctly it should be fine.

Phil - I think your stock valve was opening not because it was leaking or anything but just because of the pressure drop across the Saab intercooler. I'm assuming jason will have his BOVs on the cool side of the intercooler, so he shouldn't have a problem with the stock BOV.

[BAC5.2]

Hmmm... so you mean the compressor outlet pressure was greater than the stock BOV was allowing?

With the stock valve, all you would hear is an annoying "woooosssssshhhhhh" when on-boost.

My friend with the WRX had one on the hot side and one on the cold side of the IC, and that seemed to work pretty well for him. He was running dual atmospheric though, and never seemed to have any problems.

[vrg3]

I mean the pressure drop across the intercooler was simulating the pressure drop across a partially closed throttle plate. Read over what I said in this thread: http://bbs.legacycentral.org/viewtopic. ... 6855#76855

[azn2nr]

i was actualy goona put the stock one on the hotside right outside of the turbo. it didnt have a problem holding boost just venting the large amount of boost in an efficent enough manner to prevent surge. with the rfl im getting verry little surge and it doesnt come at a consistent rate, only if the conditions are just right. aslo the rfl stutters like a surge sound as it opens and closes to relive low pressures the volume of which is the only thing that differentiates it form the sound of surge.

on a side note even if the rfl is recirculated it will still be loud. the seal plate is smaller than the area in the vlave when opened. the sound it makes comes from the air going out and around the seal plate before exiting the vlave.