This is the big BOV thread. If you didn't find this thread, you didn't search.
This thread is where all BOV question threads get merged into.
The quote below in this first post is from our BOV info sticky and contains links to some very explanatory BOV information. Please take the time to explore the links before you ask repeated questions.
A stock WRX/STi comes with a BPV (Bypass valve) which is a vacuum-actuated valve designed to release pressure in the intake system when the throttle is lifted or closed. This air pressure is re-circulated back into the non-pressurized end of the intake before the turbo.
An after market blowoff valve (VTA) does basically the same thing BUT unlike the stock unit it releases air to the atmosphere (giving you the loud sound). Some people see an after market BOV on a stock WRX as being in poor taste (probably due to the fact that it is basically a noise maker that really as no other benefit), while others simply find the sound very attractive.
Proponent opinions notwithstanding, there is a small mechanical downside to having an after market BOV (VTA) on a stock WRX. The problem comes when releasing air to the atmosphere that has already been metered by the mass airflow sensor. When the BOV releases (blows off), the ECU will be injecting the wrong amount of fuel into the cylinders. The engine temporarily runs too rich (meaning too much fuel is injected into the cylinders). This temporary rich condition isn’t typically THAT harmful, but it may cause bucking or hesitation on lift-throttle as well as some other concerns outlined in the links below.
so nobody recommend the turbo XS? or any other 100% atmospehere venting one? nowwhat about one that may vent competely into the intake rather than 50/50? And is sems that forge is quite popular.
What other options do i have for 50/50 venting?
the guy at subaru said something about a Fastbit BOV anyone ever heard of it?
I have the turboxs RFL and love it! No problems whatsoever! I have to new one. It comes with better washers I guess. I would only reccomend this if your NOT running the stock boost.
0260B4U--the "fastbits" bov that the dealer mentioned is the GFB hybrid, 50/50 or 100to atmosphere, GFB stands for Go Fast Bits. and i think the stock bov is a 100% recirculating bov, IIRC, really, until you are boosting over 19 or 20 psi, the stock one functions fine, these aftermarket ones are pretty much just for the look/sound
hm I see, now is GO FAST a compnay in itself or would another site cary the BOV? With all the crap about 100 atmosphere guess i'll go 50/50 since I want the sound and might go with higher boost later on.
My last turbo car was a 1990 Talon TSi and I loved the loud hiss from the BOV. With my 03 rex I can't hear a damn thing!?! It seems to me that my talon was so much more fun to drive as well, and, maybe it even felt a little bit faster? Maybe this was because it was lower to the ground? What can I do to make the stock BOV louder? Is there something wrong with my head or my car? Please help.
the stock BOV doesn't vent the air into the atmosphere, so it doesn't give you that pssssst sound. If you remove the intake silencer, you will hear the turbo spool up more and also the BOV will be louder. Costs no $$ and takes 15-20 mins. If you would like that nice psssst, there are plenty of aftermarket BOV's available. Just do a search, there's tons of info on this site.
nothing wrong with your wrx. my 02 does not make any bov noises either. perhaps you would enjoy an hks ssqv. they are real loud. as for ride height my wrx is notably more tipsy thru the corners than my supra just a different kind of car. at least the rex doesn't scrape on driveways.
You won't be able to hear pressure relief from inside the cabin but it's still audible outside if you listen for it. Aftermarket BOVs cause a rich condition on idle because MAF accounts for returned air that isn't there. Nonetheless if you go with aftermarket BOV you won't need to remove the silencer to hear it.
Actually, the car runs rich in that split second the the boost is released into the atmosphere and not while in idle. When the car is in idle, the BOV is closed and nothing is being vented.
i just installed mine....i get the usual rich between shifts condition which is defined by the occasional backfire between shifts.
however...my bov makes a very odd noise at upper boost. i run stock boost and when i try to blow off ( by that i mean...go wot and get around 13psi and completely release my throttle. ) i dont get the usual PSHHHHH that my rfl makes at lower boost. Instead...i get a quick/sharp Sqeak, which is much much quieter than a lower boost bov noise. and even sometimes...i dont get a noise at ALL. this worries me alot...because i thought with more boost pressure the Louder your bov is supposed to be?