Blow Off Vavle Questions???

[CAV3MAN227]

Not sure where to post this but i figured here. I have a stock vf11 with a jdm water to air inter cooler. it has the stock bov on it that recirculates back into the intake. my question is, can this be replaced with anything better? better performance? Esp. better sound? something along the like of the hks sound. sorry if this has been asked before. any links or advise is appreciated!
-Joe

[Mattheww044]

from what I understand, there isn't really anything performance related about it. All it is doing is letting out that air built up. The only reason why I would think you would need a new one is once you start pushing quite a bit more boost... plastic won't hold up with too high of pressure... and as far as sound goes Im not really sure on our options... I had a Perrin one but flipped it for a profit

[CAV3MAN227]

i would just like one that will work with this system and sound better. hks style!!!

[Mattheww044]

Yea, they might sound a little different but I can't confirm that. The Perrin one was adjustable so that might be something to look into. They are 240 new, I bought mine almost brand new for 50, then sold it for 100. You should be able to find one for about 100 or so on nasioc. The only thing is I heard that the stock WRX/Sti ones are actually better than almost any aftermarket one.

[CAV3MAN227]

i'll have to look into that Perrin and the site u told me, nasioc. what does that stand for by the way?

[Mattheww044]

North American Subaru Impreza Owners Club

Its definately the biggest Subaru forum.
Post a WTB thread in the WTB section, and you can also search the FS sections too. Alot of those guys think that their stuff is worth alot more than it actually is so don't be afraid to throw offers out.

[CAV3MAN227]

ok kool. i will def. check it out!

[93forestpearl]

There is no point to going to an aftermarket BOV unless you are pushing much more than stock boost from a much larger than stock turbo. The rest is an exercise in futility.

[CAV3MAN227]

well like i said i just really wanted it for a different sound!

[Penguin]

when i had the stock motor I just blocked off the hose going to the intake and let it go full atm. with the air box mod it sounded AWSOME!
not like my greedy type rs but awsome for stock stuff!

[Mattheww044]

didn't it run like crap though?

[dscoobydoo]

well like i said i just really wanted it for a different sound!

But you need to realize that you will be giving up the dependable stock one that runs well and is made for your car, vs one that will probably make it run like crap just to sound better.

I have a metal one from a Supra that is almost an exact fit.
Try one of those instead- might be able to get one real cheap.

[CAV3MAN227]

well like i said i just really wanted it for a different sound!

But you need to realize that you will be giving up the dependable stock one that runs well and is made for your car, vs one that will probably make it run like crap just to sound better.

I have a metal one from a Supra that is almost an exact fit.
Try one of those instead- might be able to get one real cheap.

are u talking about like 2nd gen supras? what if i just got one from the wrx or sti. (stock one) heard they r better than ours, built better or something...

[Mattheww044]

yea they are, they are metal. But they fit directly on the TMIC that comes on the WRX and Sti. Its a different set-up, you could probably make it work somehow... but I dont really know if it would be worth the trouble.
Can anyone verify if it made a different sound after their TMIC and wrx/sti intsall?

[cartwheels]

I'm running a GoFastBits blowoff valve.



I'd like to get an adapter plate and go back to running the stock bypass valve. I love the sound of the atmospheric one, but the car seemed to be much happier with the stock part. Maybe its just the nocebo effect...

[CAV3MAN227]

wonder why our cars don't like atmospheric bov's. i heard if u have one on ur car would run lean. and i heard they run rich between shifts. what to believe...

[Legacy777]

They don't like them because our cars use a MAF sensor to meter the air into the engine. By venting that metered air to atmosphere, you are changing the air fuel ratio that the computer calculated based upon what it metered at the MAF sensor.

You will run rich when BOV is venting/open.

[CAV3MAN227]

but like in this pic of my car,

,

how can the maf monitor the air of the bov when the maf is right next too the air filter and the bov recirc's right at the inlet of the turbo... unless i'm looking at the wrong maf...

[Legacy777]

I think you may have missed my point. The MAF is not monitoring/metering the BOV/BPV directly. The MAF is metering ALL the air that has passed it and is entering the engine. This amount air is used by the computer to calculate the correct AFR. The air that is bypassed through the BOV or BPV is air that has been metered by the MAF.

Think of it this way. Let's say you're trying to make a big bowl of jello and it says to mix 10 cups of water for everyone 1 ounce of jello powder mix. That's your mix ratio or in car terms AFR.

Then let's say that you need a cup of that water for something else. You get a measuring cup and take 1 cup of water out of the bowl before you pour in the jello powder. Think of that 1 cup of water as the BOV / BPV.

If you now add the jello powder to the bowl, the mix ratio (or AFR in car terms) is not going to be the correct 10 cups water to 1 ounce of jello mix, it's going to 9 cups water to 1 ounce of jellow mix.

With the BPV, that air (water in the jello example) gets added back into engine (bowl) so the AFR (jello mix) is correct. With the BOV, the air (water) does not get added back in, and over AFR (jello mix) is not correct.

Questions?

[CAV3MAN227]

sorry for sounding so dumb, hence i am new to this car and still learning, but that was an excellent example! then in this case what can work and how should i look for it? there has to be something out there that is better than stock. maybe a better stock piece? like off of another car?

[Mattheww044]

There are plenty of recirc BPVs available, but the stock one we KNOW works and although it may not sound the coolest, its reliable and is there for a reason. You can try out diff BPVs and keep us informed, but its an expensive experiment I don't have any intention of messing with.

[ciper]

If you want a good replacement "universal" BPV look at this page http://www.alltrac.net/tuning/bypassvalve.html

[CAV3MAN227]

If you want a good replacement "universal" BPV look at this page http://www.alltrac.net/tuning/bypassvalve.html

That was very informational thanx ciper!

[CAV3MAN227]

well i found another bov/bpv off of a saab, wish i would of paid attention to what model but seems to be working fine and it sounds cool. i'll try to get a sound clip up soon!