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Discussion Starter · #1 ·
Is the WRX mass air metered or speed density? I have a friend who wants to sell his BOV to me but wants to check this info out first, because he wants to make sure I gain some sort of performance from this. Lemme know what's up. Thanks.
 

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The consensus is that you will not gain anything during shifts with an aftermarket BOV. I don't know, I've never tried one.

But the WRX uses a MAF system, and incorporates a MAP sensor as well (which apparently handles boost measurment).

VV
 

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Discussion Starter · #4 ·
Yea, that's what I've been seeing too about everyone agreeing or alot of people agreeing that there's no gain with the BOV... but what I was thinking was bypassing it instead which is totally different (right?). I dunno..

Is there some sort of bypass kit for the Greddy Type S btw?
 

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take it from someone who actually HAS one...there's a difference. I'm not going to go into great detail unless asked, but you'll see a difference. Maybe not in a 1/4 mile drag run, but if you run the car like its meant to be run (rally-style) you'll see a difference. now mind you its probably no more difference than switching to a K&B panel filter from stock, but its there (for some reason people expect a day-and-night difference). it doesn't actually increase your HP, but it gets you back into usable HP faster after a shift breaking.


i'd recomend against 100% atm.-venting valves as they will hurt performance and make your motor run worse, but the 50/50 valves seem to work fine...at the very least if you install the valve right (follow directions...read the whole thing...don't ignore anything) you won't LOSE anything...you might gain a bit.

your car already HAS a stock BOV....its a 100% recirc type so you don't hear it and "should" work fine up to about 23 PSI. all the aftermarket BOV will do is let you blow off your turbo pressure a little faster...is it worth it as a first mod? probably not. there are other things you can get for $200 that would give you more of a boost...its kinda like going after the last 10% (which is where you usually find 90% of the cost) before getting the first 90% (which is always cheaper). I'm happy with my BOV, if nothing else it kinda sounds cool, but if I had to do it again, I'd probably save up and have the uppipe/downpipe done first (and I'd have a proffesional do it). Yeah, it's breaking the law, but its a stupid law.
 

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Discussion Starter · #6 ·
The up/dp combo was my first choice but I got this good deal from my friend.

And oh yea, if it's a 100% recirc type then wouldn't that be a bypass instead of a bov?
 

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yeah, that's what you already have as a stock valve.
 

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A venting BOV may help you shift faster since you are making it run pig rich for a second and thus the revs fall faster, but then it makes your turbo spool a little slower. It doesn't really matter with the tiny stock turbo, but it will later on. This is all with the stock MAF-based system.
 

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blarg said:
your car already HAS a stock BOV....its a 100% recirc type so you don't hear it and "should" work fine up to about 23 PSI.
I don't think the fact that it recirculates is what silences it; I think it's the aircan. My late Eclipse GSX completely recirculated BOV air into the intake. In stock configuration the BOV was silent, but as soon as I put on a free-flow cone air filter, the "tweet" sound could be heard above the stereo.

BTW, has anyone measured how much the WRX stock BOV actually does hold? On the 2nd generation Eclipses, the BOV was noted for leaking pressure even as it got near max stock boost.
 
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