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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





 
#2,682 ·
I have the TurboXS RFL BOV and have lost no boost. I will admit, there is some power lost, but I don't mind. I may replace it now that I have an exhaust and intake on there.
 
#2,687 ·
I just purchased a greddy BOV

I just got my Greddy BOv (for those who dont know it is the one that is colored purple) I am going to install it 2morrow, but I was wondering if anyone knows exactly what these sound like and if they are going to give me any probs on my STI? any one know?
 
#2,688 ·
Re: I just purchased a greddy BOV

truckerspeed said:
I just got my Greddy BOv (for those who dont know it is the one that is colored purple) I am going to install it 2morrow, but I was wondering if anyone knows exactly what these sound like and if they are going to give me any probs on my STI? any one know?
can't answer any of your questions but please let me know if you have any problems after the install. i am really considering about getting a greddy type s bov so let me know.
thanks
 
#2,689 ·
Hey whats up man, the greddy BOV that you bought sound great, it has more of a long pshhhh rather then one of those high pitched sounds. You made a good choice by buying this BOV. Hope it works out for u.:wiggles:
 
#2,691 ·
dp and BOV questions

I have an Apex'i N1 catback in the mail right now and i'm trying to decide on a downpipe. I am trying to do this for cheap (college student cheap, not workin' man cheap) so I'm lookin at the HKS dp. Anyone had problems with it? What'll it sound like with the N1? would it be worth the money to get the Helix dp for the bellmouth?

second question: I've seen some people who have had bad experiences with the TurboXS RFL BOV, but i really would like that loud, get-noticed-ness it has. Anyone have it and love it? whos had problems? other options?
THANKS
 
#2,692 ·
Re: dp and BOV questions

stil2stock said:
I have an Apex'i N1 catback in the mail right now and i'm trying to decide on a downpipe. I am trying to do this for cheap (college student cheap, not workin' man cheap) so I'm lookin at the HKS dp. Anyone had problems with it? What'll it sound like with the N1? would it be worth the money to get the Helix dp for the bellmouth?

second question: I've seen some people who have had bad experiences with the TurboXS RFL BOV, but i really would like that loud, get-noticed-ness it has. Anyone have it and love it? whos had problems? other options?
THANKS

if ur not going to upgrade ur turbo anytime soon get the hks -- but if you are planning to get a belmouth or spend the extra loot and get a belmouth anyways... i have an hks dp with a blitz exhaust and man is it loud !!! remember ur getting rid of 2 cats with the DP

answer to the second no problems with the turboxs bov -- but i got rid of mine for a greddy type s
 
#2,696 ·
I bought Greddy because they are well made products and mr 700 whp supra that I know has 2 of them and had them for about 6 months hard use at the track and he hasnt any probs whatsoever, no creep no compressor back pressure nothing.;..... so in your opinion maybe it did give you problems but I installed it and it sounded just like my friends 2x Tur Supra, (Unfortunately he lives in alabama and me in cali :-( ) but if it gave you probs maybe you had a bad valve or something and should call greddy and have them replace it. Ill let you know if I get any problems but that thing sounds great and blows off real fast once you get it road tuned to how you like it to work. At first it seemed like it was leaking my boost out so I tightened it up a few turns and Boom my car was pulling as hard as &^^* once again. and was nont easy to install on the STI I had to do some minor fabrication and alteration.
 
#2,697 ·
RLsChMiDt said:
did you even think about looking into what you were buying before you clicked the "purchase" button? :rolleyes:
Oh and BTW I did buy locally and I knew what I was getting just wasnt quite sure if it was higher pitched or more of a fluttering sound. anyways I didnt want one of those RFLs they are too damned loud
 
#2,700 ·
All BOV sound different depending on how much boost you run. It should sound like air rushing out of a tube, followed by a whistleing noise.

Also, the more I read the "STi Forum" the more I realize that you people need to look at the rest of this website more often. This EXACT question has been asked an answered more times than even god could imagine. Same goes for any question about an exhaust system. Try that searching that lil' guy down there named "engine performance."
 
#2,701 ·
CKxx said:

Also, the more I read the "STi Forum" the more I realize that you people need to look at the rest of this website more often. This EXACT question has been asked an answered more times than even god could imagine. Same goes for any question about an exhaust system. Try that searching that lil' guy down there named "engine performance."
:eek: You mean theres very little need for a sti forum!!! No way;)
 
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