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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





 
#3,752 ·
I think it was worth every penny. The bling factor under the hood is nice. Not to mention just the whoosh I can hear in first & second puts huge smiles on my face. If you have the extra cash I highly recommend it.
 
#3,753 ·
Thanks for your input. I got the cash, but I am just unsure as if to get it because I have not heard it first hand yet. I have heard the HKS, TXS, and the GReddy Type-S, but nothing else.

I have heard and seen the sound clips, but nothing is like experiencing it first hand.
 
#3,754 ·
You might want to try adjusting the spring inside the BOV to the loosest setting. That's where I have it, and it blows off at all gears, at anything over 3k rpms. It's not really loud inside the cabin, but with the windows rolled down I can hear it very well. There is also a plug in the firewall beneath the pedals in the footwell. With that removed, you can hear the BOV succinctly.
 
#3,756 ·
feedback on mods I did: Worx BOV, HKS and HELIX

Just got my ish isntalled at Racing Trenz in Denver, Co.

WORX BOV - This is LOUD yo! I did'nt really want to be that annoying on the road, but it's definitely cool. However, since the adjuster goes in continual circles, how do I know when I am at 50/50 or 100%????

HKS Carbon-Ti + Helix UP/DP - These elemnts combine for a SWEET sound. No loud annoying rice can sound. It's a Clean, Low rumble just like I wanted. If you don;t want to deal with being too much of a loud a$$ on the road, this is a good mod-combo.

HKS TT - a TT is a TT. Got it on and I like the added piece of mind of not having to sit in my car on a hot day to cool it down (even though most Rex owners say I dont need to do this neways).
 
#3,757 ·
bump, anything else?
 
#3,759 ·
ebr0t said:
you are in DIRE need of searching it seems. kill the cats.
alright got everything i need, thanx for all the help :wiggles:
 
#3,760 ·
Seems more and more people are getting the WORX bov. OR maybe I'm just noticing the posts lately. In either case, the response seems to be positive from most.

I wouldn't dream of having an aftermarket BOV until I get a tbe put on my car. The rice factor would be too high and it would just be ridiculous.

Mods sound good, so far.
 
#3,761 ·
I have a Worx and I've never thought it was loud. I even switched from the regular ring to the "loud" ring. I don't have that much exposure to other BOVs in person, however. Perhaps mine is loud? I kinda hope so, just so I can turn people's heads. They can't see me through the tinted windows.
 
#3,766 ·
TIAL bov issues..tech help needed

Heres the prob. I had my second HKS bov seize up on me sunday. It wasnt opening at all. From what I was told is happening (and makes sence) is water from my open hood scope is getting in it, heating up, drying the rubber and making it stick. I tried oiling it up and nothing so I got a new valve.

I got the Tial

Now the Tial valve is only opening alittle bit at low boost, and doesnt at all at high boost (higher rpm's) wierd huh.

Problems I know the car has through a check engine light check up

- Fuel level sensor (cant be it)
- CPS crank position sensor (keep this one in mind!)
- Fuel vapor leak (prob. a bad gas cap and unrelated))

I ran a Vacume check on the line going to the Valve yesterday BEFORE the new valve went on) it checked out fine "normal engine operation" it said.

Today with Tial valve on I ran the V-check again and it came up the same but when i reved the engine it came back to idle and vacume read "late ignition timing" and stayed there. (My guess is late ignition timing is timing being pulled?? and when i reved it a bit the timing pulled?

I don't see how the vacume could of went bad over night, or with the new valve on there. Im thinking that the CPS (CRANK POSITION SENSOR) is pulling timing and SOME HOW messing up my vacume???

To answer some qs. that you might want to ask if you can help-

-Its Tial BOV with 11lb spring (Im running 17psi so should be good there)
and this Valve can not be adjusted.
-I took the valve off and put it back on making sure everything was straight.
-Vacume checked out fine yesterday but is talking sht today
-no kink's in lines I checked 100 times.

Of course theres always a possibilty that I got a bad valve. If not Im thinking something with the crank sensor with it some how messing up vacume (which ive asked around and was told it couldn't be, but in my eyes could still be)

Any help will be greatly appreciated for I am a worrier haha!

Bob

P.S new Crank sensor is in the mail...
 
#3,769 ·
welcome to the club.

quick tip for ya:

do a search for BOV and youll see its not a good first mod as its all show, no go.

spend your money on a better mod and thats the general concensus.

hit up that search though and read the reviesws if you decide to still get one.

GFB hybrid is the best ive *read* about, you can go from closed to fully atmospheric and everywhere in between.

after reading youll see why the WRX doesnt need/benefit from one.
 
#3,770 ·
pretty much what they said, but if your set on a BOV, i think the hks ssq sounds excellent and i know of at least one person in particular who hasn't had any kind of problems. but if you want to hear the stock BOV, take out the intake silencer. thats what i did and i'm happy with it.

good luck modding and welcome:)
 
#3,771 ·
top right of screen in blue, second from the farthest right... SEARCH. this will be very helpful in finding the answers to many of lifes wrx related questions.

I run a forge BOV with medium spring (100% atmsph.) I really like it... no problems, sounds good, and is one of the only BOV known to not cause problems



 
#3,772 ·
Dont know how long you have had your rex or what mods you have done as of yet. but a BOV will do one thing and one thing only. a different tone PISSSSS. that is no hp gain nothing. but if you want to here the bov from stock that works well after a few mods like upipe and downpipe as others can tell you then get like a AEM Cold Air Intake. then you will hear the bov like a loud fart. It wount have the whisle sound but it's cheaper.

typing police "wich" :p j/p I do it all the time.

welcome... if you are new to wrx-ing then I would say you have much to read. I would start with stickes then move to your next mad like uppipe search as there are many different MFG's of them. Also know there are a few threads on what wont cost much or anything. also worth looking at.
 
#3,776 ·
you're really better off w/ the stock unit. surprisingly, it holds boost pretty well. although, there are some who say they have bad stock units. undoubtedly, there are probably flukes out there. but, until you're forced to switch to something b/c of an intercooler swap, stay stock. get an uppipe.

sounds great, sure. but, there are many who have complained of bogging. it's up to you, though.
 
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