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"The BIG BOV thread" (Where all bov question threads get merged)

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#1 · (Edited by Moderator)
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.

Thanks!


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.


Links for BOV info:

Sinister's BOV FAQ

Wikipedia

Unabomber on Nasioc

Davenow on Nasioc





 
#1,258 ·
Just ordered my Stealth hybrid GFB I'll let you know how it goes. totally adjustable for if you just want the soudn the able to be louder once you start increasing boost.
 
#1,273 ·
i know two people, one with a hks which sounds obnoxious and annoying after a while, and one who just got a forge two days ago and it sounds amazing, if you have ever watched wrc or even are remotley interested in rally then go with the forge, not to mention its much cheaper and dosent sound like a burping snake
 
#1,275 ·
Bummer...

I believe I purchased the last Forge BOV from Stratmosphere that they had for the WRX.They will be concentrating on their Audi/VW forte.
I know there are many other Forge distributers , even Forge themselves , but Stratmosphere was great to work with.BTW , mine is anodized blue and if you think the silver one is pretty this one realy takes the cake.
 
#1,276 ·
The HKS sounds excellent but made my car run terrible. I sold it and bought the GFB and I'm running that in hybrid mode. I am VERY satisfied with the GFB. It is not nearly as loud or cool sounding though. It doesn't make any noise unless you really spool up the turbo, and when it does it sounds like a clean pssshhhh sound. The HKS had a cool squeal. One thing I didnt like about the HKS was that it released and made a fairly loud noise with even the slightest throttle release. I think it would have gotten annoying pretty quickly for my tastes. I'd recommend the GFB... got mine from mastrowrx.com :)
 
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