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Best BOV for a wrx

20K views 64 replies 26 participants last post by  Cosmo 
#1 ·
I need some advice from anyone's experience on which Blow off Valve has had the least problems and the best sound and performance.. Thanks !Thumbs Up
 
#28 ·
mrpoman99 said:
Whole lot of confusion going on. If your going to get one, go with the dual ports. I have a Turbosmartdual dual port 50/50 or what ever you wish, fully adjustable either way. If you have a standard BOV it will plug the recirclation valve, the ECU will still think the air is being cycled, so you'll run rich. Over time this isn't good, and the benefit of a 50/50 is that you'll get the protection for your turbo from the atmosphere blow off, to keep your turbine spinning, less lag, and the recirclation dump like the stock, so your 4 stroke will be fine and dandy. Best of both worlds. Down side is they are expensive, Mine was $280. That was even a good deal. Cool? -POMAN
That is incorrect. An atmospheric vent BOV will not make your car run rich. The stock bypass valve "protects" the the turbo just as much as an aftermarket BOV does, they just do it in different ways.

In fact, most problems are reported from 50/50 valves.

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#29 ·
So cosmo, i know this had been rehashed again and again but i want to be sure. I have a slightly modified 04 wrx sedan. I have helix catless flex uppipe, and helix downpipe. Thats about it for performance mods. I did the intake silencer removal and plan to add cat-back very soon. Anyways - I just picked up a used HKS ssq BOV for a very good price. If installed correctly will i have any issues? I dont plan on doin too many more mods. I know the aftermarket BOV is purely for sound unless you go with bigger turbo, higher boost setup, etc. but i love that sound!
 
#35 ·
Turbo XS RFL

Havent posted in a while but moneys been real tight (havent made any mods worth bragging about). I'm getting the turbo xs turbo back exhaust with race pipe and perrin up pipe soon and was going to order a bov at the same time. I'm leaning towards the turbo xs rfl only because I like to be obnoxious. Anybody, is this gonna throw off the cel or make my rex run like garbage or am I safe with this bov. Thanks for the input.

(sorry for the confusion on my post, had to edit)
 
#38 ·
As far as effecting (or affecting I never get them straight) performance, I believe the stock ECU is used to and expects the BOV (or air bypass valve) to shoot a burst of air back into the intake when you shift. If you take that air out, you would end up running rich during shifts. Makes sense to me, but I'm no scientist nor a turbo expert.

So, if you have EM you can deal with the fact you aren't getting the recirculation and make your map accordingly. I also agree, no performance gain, just needed when high boost levels are desired.
 
#43 ·
lobsterhat said:
As far as effecting (or affecting I never get them straight) performance, I believe the stock ECU is used to and expects the BOV (or air bypass valve) to shoot a burst of air back into the intake when you shift. If you take that air out, you would end up running rich during shifts. Makes sense to me, but I'm no scientist nor a turbo expert.

So, if you have EM you can deal with the fact you aren't getting the recirculation and make your map accordingly. I also agree, no performance gain, just needed when high boost levels are desired.
That's not true. The throttle body is closed when the BOV or bypass valve opens, so that air wouldn't be going into the engine anyways. Plus, when the throttle body is closed, very little fuel is coming out of the injectors.

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#45 ·
Cosmo said:
It should hold up to 30 psi. What kind of turbo are you running to make 25 psi? Are you still on the stock block/heads?
BOV for all you that dont know is to release pressure! it make a sweet noise especially TURBO XS, or HKS, and prolongs the life of your turbo! also it stops the back pressure so when u switch gears it prevents the turbo from spinning backwards! (FOR ALL U NOBBIES) and prevents what some call turbo lag! IF U WANT TO BE ALL TECHINCAL! no oviously it dont make u go faster but again makes the turbo last longer and keeps u at a higher boost instead of getting more lag!
 
#47 ·
^^^Another BS flag has been raised by me. A BOV doesn't prolong the life of your turbo. The stock bypass valve does just fine, if not better than the aftermarket ones, that is up to about 21 psi. Preventing turbo lag, that is BS as well. Turbo lag is just the time it takes for the exhaust to flow fast enough through the turbo to spool up the intake side of the turbo. Stops backpressure? I think not. Yeah a BOV will prevent the turbo from spinning backwards, but the stock bypass valve again does as good of a job if not better than an aftermarket, up to about 21 psi. It doesn't keep you at a higher boost either, and the level of boost has no relation to lag. I might have said a few things wrong but basically the only thing you said right in your post was they make a cool noise and it doesn't make you go faster. Please know what you are talking about before trying to give advice.
 
#48 ·
IBAUCLAPlaya said:
^^^Another BS flag has been raised by me. A BOV doesn't prolong the life of your turbo. The stock bypass valve does just fine, if not better than the aftermarket ones, that is up to about 21 psi. Preventing turbo lag, that is BS as well. Turbo lag is just the time it takes for the exhaust to flow fast enough through the turbo to spool up the intake side of the turbo. Stops backpressure? I think not. Yeah a BOV will prevent the turbo from spinning backwards, but the stock bypass valve again does as good of a job if not better than an aftermarket, up to about 21 psi. It doesn't keep you at a higher boost either, and the level of boost has no relation to lag. I might have said a few things wrong but basically the only thing you said right in your post was they make a cool noise and it doesn't make you go faster. Please know what you are talking about before trying to give advice.
I concur.
 
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