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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





 
#2,627 ·
No problem with mine. Just make sure the spring is tight enough so that it holds boost and idles fine, and you should be ok.
 
#2,635 ·
qbbraveheart said:
hmmmm some have problems..some dont :confused: :confused1

what are your mods?

oh...HKS also makes it just for the STi now...so im going to go with that and see how it goes :confused:
The closest I've done to a performance mod is removing the intake silencer. Soon I'll be ordering a downpipe. The kit fits perfectly and required no adjustments for me. Maybe others tried to adjust it or something.

RN
 
#2,637 ·
#2,638 ·
Silverbane said:
Heres a link as to why aftermarket BOV's cause these "problems".

http://www.imprezawrxsti.com/postnuke/index.php?name=PNphpBB2&file=viewtopic&t=5459

Hope it helps you guys understand whats happening.
im well aware of the problems with BOV's and the STi and all that other good stuff

whats weird is some are having problems...others arent :confused:

what i would like to know is:
there is 2 different kits for the HKS SSQV BOV
theres one for the regular WRX
and one just for the STi

those who are having problems....which one are you using???
the one for the regualr wrx
or the one just for the STi?

im trying to see if they changed the BOV from the regular wrx and the STi
what i really mean is are there 2 different BOV's...
 
#2,639 ·
qbbraveheart said:
im well aware of the problems with BOV's and the STi and all that other good stuff

whats weird is some are having problems...others arent :confused:

what i would like to know is:
there is 2 different kits for the HKS SSQV BOV
theres one for the regular WRX
and one just for the STi

those who are having problems....which one are you using???
the one for the regualr wrx
or the one just for the STi?

im trying to see if they changed the BOV from the regular wrx and the STi
what i really mean is are there 2 different BOV's...
The BOV itself would be the same. And since either one fits, I'm assuming the base pieces used to bolt it on are the same but just listed differently so the STi guys don't have to ask if the WRX kit fits.

RN
 
#2,640 ·
renichms said:
A car *bucking* due to an atmospheric BOV? It may have happened, but come on. Mine's given no problems whatsoever, so I'm sticking with it.

RN
I also said it vary's from car to car. Do this on an MR2 and they run so rich they have shut off mid-shift. Its an explination of what is going on, I never said to get rid of you bov :D

Its simply information for people that wonder why this happens when they switch to an aftermarket bov not a "Sell your BOV's now" Statement :D
 
#2,641 ·
renichms said:
The BOV itself would be the same. And since either one fits, I'm assuming the base pieces used to bolt it on are the same but just listed differently so the STi guys don't have to ask if the WRX kit fits.

RN
yea its the same part #

so the people having problems with this BOV what are you experiencing???
running rich?
turbo lag?
stalling?

im going to contact HKS and see what they have to say about it
 
#2,642 ·
The HKS BOV, IMO is a better bov compared to spring loaded (Push vs PULL) BOV's. It reacts very quickly to pressure changes, a very good quality BOV IMO. The running rich/lag issues depend soley on how much fuel your computer dumps compared to how much escapes when you shift.
 
#2,643 ·
Silverbane said:
I also said it vary's from car to car. Do this on an MR2 and they run so rich they have shut off mid-shift. Its an explination of what is going on, I never said to get rid of you bov :D

Its simply information for people that wonder why this happens when they switch to an aftermarket bov not a "Sell your BOV's now" Statement :D
The thing with the MR2 shutting off sucks dude, sorry to hear about that. In my observation, the STi isn't much affected by it. My mileage has remained the same, lag (what little there is) has not been increased at all, etc.

I know you didn't mean to sound like you wanted us to get rid of the BOV if we had one already...sorry if I came across that way. It's also easier to switch between stock and aftermarket or vice-versa if you can install it yourself...so if it doesn't work you don't have to pay someone else to swap again. ;) Excepting for one clamp, mine was a 20 minute install. Rant over.

RN
 
#2,645 ·
qbbraveheart said:
so how easy is it to install that BOV?

anything special needed?
I'm hardcore postwhoring on this thread. :D

To install a BOV, you need: hands, tools to loosen and tighten the bolts (good ol' socket stuff), patience and the BOV kit. One person can easily do it, but two make it easier with some of the @#$% stock clamps on the hoses. The HKS kit comes with good instructions and even includes the plug for the recirculating hose.

RN
 
#2,647 ·
Blitz BOV

Hi all,

Does anyone have the Blitz BOV installed on their STI? Did the installation cause any problems? and how is the BOV performing now that it's installed? I have searched for this but it seems that there are no Blitz BOV for the STI right now and i like that sound the best, any info would be greatly appreciated.

Thanks in advance.
 
#2,649 · (Edited)
I ran the Blitz DD on my STI for about 1 month. At low RPM's, I did experience some strange idle characteristics no matter how much I tried to adjust it.

Most of the BOV's should work on the STI with the addition of shims if necessary depending on manufacturer. However, you will probably be more satisfied with a BOV that does have some recirculation such as the WorxTuning or TurboSmart.
 
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