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

2M views 12K replies 2K participants last post by  WRX-maniac 
#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





 
#8,166 ·
yeah im thinking about getting a hks one? ? ?good or bad choice :screwy:
I had the HKS SS BOV on my old 03, it works and sounded great. Look into a Tial though... I think you wont be disappointed.
 
#8,180 ·
But given that there's not a train in existence that can instantly accelerate to over 100mph, there would still be quite a bit of error in the calculation.

The train will not fly.
 
#8,182 ·
If it accelerated to 150 and stuck there for a few minutes then dropped down to 130 and was a tilting train so it didn't have to decelerate for corners... then it's possible.
 
#8,190 ·
I think we have 1 of these posts a week. it's fine! If you're really concerned about what makes the sound...Use search on the top menu bar like you should have in the first place...
 
#8,191 ·
Yo Sinister, If this is about the question i asked, ya know it would have taken you a quarter of the time that it took you to write this to just answer the question. my question was if some intakes make a slight BOV sound....im not concerned about anything...its not on my car...just wondering, way to be a dick about it.

P.S. I did you the search on the menu bar...it brought me to this thread, and im not about to read through the entire BOV thread that started in 2001.
 
#8,192 ·
#8,193 · (Edited)
#8,194 ·
#8,195 ·
how to install a bov

hey i know its prob one of the most stupidest questions to ask and you guys have prob answered this but i just bought a SSQV bov for my 06 subaru. and i'm just wondering how to do the hoses. i put the ssqv on and i hooked up the stock hosing up to the bov and i pluged up the return hose. and i started the car up and it idles really rough. the engine revs by itself to prevent it from turning off. and then it just putters out. i'm not really sure out to install the hoses or how to set them up. can sumone help
 
#8,197 ·
I would delete this if I were you. It should have come with instructions. I really hope your serios and not messing around. But I'll tell you how.

1) make sure you have an adapter flange.
2) remove stock BPV on the I/C, 2 12mm bolts, 1 "pinch" hose clamp, 1 vac line, don't lose or rip or gouge the gasket.
3) install new BOV onto flange
4)Plug recirc hose with hose plug, use new wrom type clamp aka screw in type
5) take gasket and put between I/C and BOV
6)Bolt on new BOV, make sure you haven't lost the triangluar gasket and is seated properly
7) Hook up the vac. live to the nipple the size of the ID of the vac. line.
8) start up the car, make sure the idle is steady, if not you have a leak.
9) go drive it, make noise, and make sure that your rpms don't drop off when you shift to neutral
10) come back on the forum, read stickys, FAQ, or SEARCH!!!
11) install stock BPV



I don't know why I did all this typing!?! I could have been a D**KHEAD and said just search, or just gave him a simple link with no other words
 
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