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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





 
#1,028 ·
If the STi is anything like the current WRX here are the answers:

1. EASY.
2. $225+ for the "better" ones
3. Lots of places (look at our vendor section)
4. Most like the HKS SSQV, Blitz DD, and/or GFB
5. Hurt as in destroy? No. Hurt as in reduction of performance? Most will say yes (I had hesitation issues with my GFB 50/50).
 
#1,030 ·
The v2 was revised to increase clearance between the intercooler and a/c lines (v1 had NONE :D) and to allow for (some) aftermarket BOV's to be installed. Plus it's nice and shiny with improved end tanks and is lighter.
 
#1,031 ·
Okay, final question from me...how loud is it when compared to say, a Blitz or HKS? Is it loud enough for people on the sidewalk to hear?

I just wanna make sure it can be heard over my exhaust...hehe
 
#1,033 ·
definetly loud enough, i've scared plenty of people walking on the sidewalk. hehe

its by no means txs-rfl loud (too loud) but it sounds really good to me.
 
#1,036 ·
I had it, it sounds really ,,,,,, good. ( or bad, depends on the taste, it is a high pitch whistle )
I got rid of it because my car suffered poort gas milage ( like it is going to make much different with my set up ) and jerkyness between shifts ( my girlfriend hates it so bad she refused to get into my car )
there is this one post about the hks exhaust, you can hear the HKS ssqv in the short video.
quality wise is great, also a great engine dress up mod.
good luck
SL
 
#1,038 ·
yep, that's the one.
that is the most i've seen it cost though:eek:
i paid 109 for mine
 
#1,040 ·
I'm definatly getting one of these. I wanted a BOV, but a lot of people say most of them cause performance issues. I'm glad this one doesn't and it sounds ballsy. =)

How is the install? I know it's just bolt on, but it there anything I should know about? Can I just tighten the bolts or do they have to be at a certain torque?
 
#1,041 ·
yeah just tighten them so they're snug (so you know they won't fall out) and don't forget to put the vacuum line back on.
 
#1,042 ·
Verdugo said:
Okay, final question from me...how loud is it when compared to say, a Blitz or HKS? Is it loud enough for people on the sidewalk to hear?

I just wanna make sure it can be heard over my exhaust...hehe
It's louder than the Type-H and gives a more sustained duration vent. It also does not flutter at low vent pressures like the TurboXS unit does.

I had it on my car and for some reason it would not vent with my setup (altitude? TMIC?), but I've heard it on other local cars and it sounds great.

-Pace
 
#1,046 ·
its making the longer and louder sound because 100% of the air is coming out... so the gate opens for a longer time.....

u should set it at 50/50... u probably will have to buy a stock BOV... take off the pipe that connects to the recirc. hose and dont forget the black O-ring either... and take off the side cap of the GFB BOV and connect the recirc. pipe and hose onto it....

it has also been argued on this board that 100% vent could actually hurt your performance....
 
#1,048 ·
Has there been a conclusion made about 100% atmosphere BOV's?!

With tax season rolling around, I'd really like to put a little money into my car. A BOV is one of the things that I want. A lot of purists say that "the stock one will hold boost up until 20 psi" or whatever, and I am aware of this. I just want the cheap thrill of the sound :)

I read one thread like this and a guy talks about the normal problems of decreased gas mileage, stumbling etc.


Before that I read a thread like this where everything is fine.

I'm torn. :(

Has anyone found what will determine whether or not you will have problems? Or is the general consensus that you just have to spend the money and find out?
 
#1,050 ·
Where and how much? I looked around and they seemed to retail for $150-200, but they were on ebay last week for $109,does not look anymore are up for bid, and I would much rather pay the lower price.

-joe
 
#1,051 ·
i ordered it from rallyperformance for $190 (YIKES!)...the only other place i saw them available is directly from forge....they charge $150 but that doesn't include shipping and customs from the UK...

i figured that i have a fat tax return check coming and i can swing it :D
 
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