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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





 
#1,457 ·
I've put at least 75 miles on it, and I'm still having the same problems. It seems like I'm losing power because of it. It seems as if it's bleeding while in boost....if I got the red spring, do you think it'll still vent!? I'm running stock turbo with 15.5 psi from a JoeP. :confused:
 
#1,458 ·
i was running into the same problem...give it 25 more miles...if you are still running into problems give forge usa a call and explain the problem and they will send you the correct spring...i have not heard of anyone having so many problems that they have had to take the forge off....

i think the red spring may work...
 
#1,465 ·
That's it.

WRXin' said it all, go to their link and you can even listen to a clip.
Forge is a UK company specializing in billet products.This BOV was anodized at the factory.It is 100% VTA and is mysteriously one of those 100% BOVs that do not seem give any of their owners grief other than changing the springs to accomodate non stock boost applications.Forge Motorsports will answer all your questions and supply replacement springs.
I do not know if anything has changed , but when I purchased mine , Stratmosphere said they were no longer stocking parts for Subarus , only Audis. Call them up.
 
#1,469 ·
WRC_Obsessed said:
again...i would suggest that you give forge usa a call...they are a great help and will send you exactly what you need to fix the problem...

great customer service :cool: :D
definitely do that. they are great guys to ask, especially about their own product. oh yeah, and my forge keychain looks killer :) i sold the bov in favor of an hks unit, but not for any mechanical reason. it simply wasn't the sound i wanted.

if you don't call them, at least send them an email. now where's that keychain... *scrounging through desk*
 
#1,470 ·
I read the post, I was just hoping that he gave stratmosphere as a recomendation and got it somewhere else - stratmosphere doesn't carry WRX BOV's any more since like 6 weeks. Just really wanted a blue one but Forge doesn't list one and Stratmosphere ain't sellin' 'em. oh well, thanks for the replies.

As for the description, thanks but I've heard plenty about this valve - I've been browsing these boards for over a year and have yet to come across a negative post about Forge's valve or their customer service. The same can't be said of the others...;)
 
#1,474 ·
Cheap , Cheap!

I got the idea from one of my son's friends who did the same to his little Honda.
That is simply plastic convoluted tubing that you can buy at most performance shops , the best is Taylor brand (they make plug wires too) , the Spectra brand at Kragans etc. is not uniform in color and thickness. the blue pieces are just 6 coats of Duplicolor Ceramic engine paint on any removable piece I could take off and sand , why didn't I do the belt cover???I ran out of paint!
The WRX on the IC was done with a cardboard stencil I made by carefuly measuring and drawing the WRX logo onto a piece of bannana box from Costco , lots of newspaper and masking tape to protect the car and there you have it. One weekend and about $40 in materials , Don't forget to replace all the zip ties with colored ones!
One day I'll do real Samco hoses but for now this was a fun project for me and the kid.
JV
 
#1,475 ·
stilesg57 said:
I read the post, I was just hoping that he gave stratmosphere as a recomendation and got it somewhere else - stratmosphere doesn't carry WRX BOV's any more since like 6 weeks. Just really wanted a blue one but Forge doesn't list one and Stratmosphere ain't sellin' 'em. oh well, thanks for the replies.

As for the description, thanks but I've heard plenty about this valve - I've been browsing these boards for over a year and have yet to come across a negative post about Forge's valve or their customer service. The same can't be said of the others...;)
IMO I would go with the GFB Blue Anodized 50/50 BOV. I've had the GFB (RED) on my car for well over a year now, and it's been GREAT.
 
#1,476 ·
Stock bov question

When I forst put my mbc on the car it was tuned to 15psi with the stock bov vented to the atmosphere (not the smartest thing in the world)..my question is could the stock bov leak some boost up top because when I got my forge bov the other day..I put it on and took it for a drive and hit the cut in 3rd...I dont have a boost gauge, I was using a friends gauge to tune the car..I turned the boost down to god knows what and now it works fine..but it is slow becuase I dont know the psi....could this be true
 
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