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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





 
#1,502 ·
EMarkDDS said:
From the sound of things, it seems an aftermarket BOV isn't going to be of any real benefit until 20+psi. Personally, I'd rather put my cash towards a nice catless STi uppipe or a turbo-back setup.
Oh yeah, you should definately get your basic mods before a BOV. By basic I mean exhaust, uppipe, boost controller, etc.
 
#1,503 ·
jsmonet said:
i got flamed on many occasions for saying that on nasioc.com... even though i HAVE a bov and the flamers don't. go fig :rolleyes:
Flaming is dumb and so are they who do it. I know thats sounds childish and hypocritical considering the statement I just made, but I stand behind it.

Didn't you know? having an opinion can be considered a crime.;)
Thats why this forum is so much better.

Back on topic though, I have a blitz DD. I like the sound and wanted it, and I got it used with the adaptor really cheap. My motor stumbles a little when I get off the gas really quick, because it gets a little too much fuel. Other than that, I dont know of any other problems.
 
#1,504 ·
jsmonet said:
i got flamed on many occasions for saying that on nasioc.com... even though i HAVE a bov and the flamers don't. go fig :rolleyes:
A lot of people read things and regurgitate it verbatim without any experience or thought going into it. They confuse this with knowledge rather than random information. Wouldn't worry about it.

My BOV was not propoerly adjusted for my car when I first put it on and it ran terribly bad (opening at 4psi!!). But now it is adjust correctly and works fine!
 
#1,505 ·
Well, I am far from a pro at this stuff, but I can speak from my own experience.

I have the Go Fast Bits StealthFX blow off valve and the Unifilter RamPod intake on my car, and I have not experienced any problems with either one. The only issue I had was with the blow off valve during the first week or so because it wasn't broken it and I was having a hard time turning the adjustments. Now I am running the BOV at about 30 - 40% atmospheric vent, and everything sounds and runs great.

FYI, I just ordered my gauges this week, and I will have an air/fuel and EGT gauge installed soon, so I will actually be able to tell if the intake is making the car run lean like a lot of people say they do.
 
#1,506 ·
E23K13L420 said:
Are Short Ram Intakes better than Cold Air Intakes?
Yes, the short ram is most definately better. CAI have been proven to decrease performance on our cars. The cold air you're getting gets heated back up by the turbo anyways, so it deems it pointless.

There have been numerous discussions about this topic. If I haven't answered your question adequately, you may want to try a search :)
 
#1,513 ·
i am looking at that bov also... i am not sure if the SSQ is louder, your best bet is to look on vendor sites for sound wav and video of the files and try to compare them. i know turboxs has a video of theirs on their site... hope this helps a bit. I have been in a car with the txs bov, and it is a very very nice sound. but i have not heard the ssq in person.
 
#1,514 ·
I have the TypeH.. it is pretty loud, engages everytime you put moderate load on the engine... you have to be granny driving not to make the sound.

It is about the same loudness as the SSQ, but isn't a shrieking sound, instead it's a longer psssssssssh sound.

You might get some fluttering at first, but wait until the spring gets seated to fiddle with the packing washers to adjust it.
 
#1,515 ·
hey eli, u know i have the type-h, and i love it. it always sounds a lil different, and sometimes by going half throttle i can make it shriek almost like a SSQV. anyway, it's a great bov and vents nicely because of the multiple holes... air has a better time going multiple directions than being forced through one hole (for example the RFL).

Jim
 
#1,517 ·
there is already a spring in it. The others are different tension if you need them for your set-up.

Install the BOV and see.

IF you need to change the spring - undo the hex screws and the thing pops apart (just hold it all together as you release the tension on the spring - it is a very simple mechanism - you don't really need instructions.

If you are worried - call George at Forge Motorsports in Florida - he gives great support of Forge gear.

Cheers,


Andrew
 
#1,521 ·
Question for Forge BOV Owners

I just installed my Forge BOV. IT has a nice sound most of the time, but sometimes I only get a flutter instead of the whoosh... Is this normal? Or do I need to install the stiffer spring? I usually get the flutter when I'm not going from WOT. Also sometimes I get the flutter right before I get the whoosh. Again, is this normal?

-MK
 
#1,524 ·
I get the same thing. I have not tried the other springs yet (I have all three) and I will when I get my car back. I agree with Richard, you probably need a softer spring....but I think a lot of people have similar situations with both Forge and other BOVs.

-joe
 
#1,526 ·
Ok, I'm gonna try the softer spring within the next few days. I guess that does make sense since the softer spring would allow it to open with less pressure (ie when I get the fluttering). Thanks for the help guys. I'll report back when I make the change.

-MK
 
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