"The BIG BOV thread" (Where all bov question threads get merged) - Page 203
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This is a discussion on "The BIG BOV thread" (Where all bov question threads get merged) within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; Originally posted by t I'm currently stock waiting for the warranty to end, so this gives me time to think ...

  1. #3031
    Registered User TurnWRX's Avatar
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    Re: BOV question

    Originally posted by t
    I'm currently stock waiting for the warranty to end, so this gives me time to think about what I want to do, Iv'e read in a few threads that Bov decreases the engine performance when the turbo is stock, why is that ? My understanding was that the bOV opened to let air into the turbo when you're not on the throttle to keep the turbo spooling.

    While we're on the subject what's a everyday turbo , that I don't have to worry about detonating my motor with? Responses greatly appreciated.

    - thanks

    Technically, when the bov vents 100% to atmosphere, there isn't air going back in. The turbo is suppose to be spinning freely at the time, which would help the turbo spool quicker when shifting (at least that's what I've read). But most (ok, all) people haven't noticed any increase in performance.

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  3. #3032
    t
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    Re: Re: BOV question

    Originally posted by TurnWRX
    Technically, when the bov vents 100% to atmosphere, there isn't air going back in. The turbo is suppose to be spinning freely at the time, which would help the turbo spool quicker when shifting (at least that's what I've read). But most (ok, all) people haven't noticed any increase in performance.
    I don't mind not having a performance increase I just really like the sound for some reason.....and do you know of an everday turbo ?

  4. #3033
    Registered User scooby24's Avatar
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    The BOV will cause the car to run very rich for the brief period that it vents boost into the atmosphere. This is because when the throttle body closes and builds up the pressure to release the BOV, instead of the air staying in the intake, it's releases, causing an excess of fuel and shortage of air. However, because it's only when the throttle body is closed, you should not notice any sort of performance change. I'm running the TurboXS RFL and love the sound and haven't noticed any performance change at all...which is a good thing!

    Also on a side note...I called Subaru and asked them about an atmospheric BOV and they said it wouldn't void the warranty
    05 Crystal Gray STi
    304 hp 353 lbs on 92 octane ------> Mustang Dyno
    12.6 @ 109.2 > new numbers coming soon.

  5. #3034
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    you can always just install the BOV on a different intake pipe. then if you ever needed to go to the dealer you could place the origina BOV back on the car. If you have a turbo you must a have a nice BOV. just make sure when some guy in a honda wants to race, becuase you popped air in his window, that you smoke the krap outta him.

  6. #3035
    Banned emosubaru's Avatar
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    for that brief period of time it will not run rich on Mass Air Sensor cars because the fuel injection recognizes how much air is in the intake path. it also does not matter when you run rich for that period of time because there is no risk of detonation (the main problem with rich a/f ratios) during a blow off valve egress.

    blow off valves are not made for aesthetic, they are not made for performance. their primary and most important function is to combat or eliminate compressor surge, the shock of the throttle body closing under boost. the resulting shockwave will travel through the boosted air and hit the compressor blades, shoving the compressor wheel up against the bearings. this is bad for your turbo and can cause wear over the long run.


    tuning a blow off valve correctly is essential for this reliability gain to be attained. if the spring is turned too tight(usually because the person wants a high pitched sound associated with high-boost cars' bov's) it may not release all of the air quickly enough, and the shockwave will travel through the air that cannot escape fast enough. when a bov "shudders" or has an echoing sneeze sound to it, usually the bov is turned to tight. that sound is the shockwave bouncing back and forth in the intake runners. if the spring is too loose, the bov will not close quickly enough to seal off the intake runners and you will have the danger of running rich for too long.



    if you want the blow off valve for the sound, then you are, by popular definition, a ricer.

    come to terms with it. i'm proud of my few ricer tendancies(i like atmospheric bov's, so long as they are tuned properly and don't echo), i like JDM sidemarkers(yes they're flashy and unnecessary but hey, they are safer) and i like lowering springs and camber ajustable suspension. it makes the car look better, no matter if it is right for the car's suspension setup and geometry.

    come to grips with being a ricer. you don't have to like altezza tails and vinyl (i hate both) but don't be ignorant just because you like something. you can't change the right definition of something just because you're too vain to call yourself a ricer in some regards.

  7. #3036
    Banned hippy78's Avatar
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    for that brief period of time it will not run rich on Mass Air Sensor cars because the fuel injection recognizes how much air is in the intake path.
    That's not true. The maf is the reason the car runs rich with atmospheric bov's. The maf sees how much air goes in, and the ecu fuels the engine depending on the maf reading and a few other things. When we shift, and an atmospheric bov opens, it lets air into the atmosphere that the maf already metered. Since the ecu thinks that air is going into the engine and not into the atmostphere, it fuels the engine for the amount of air that is going into it and the air that left the bov(cause the maf doesn't know the bov let air out).

    Most people think the stock bov is pretty cool. Even if people say that aftermarket bov's won't void your warranty, you don't wanna be the one going to subaru with the dead engine. They might just say that it had something to do with your malfunctioning aftermarket bov and that you have to pay to fix the engine(it's happened to more then one person). Not that you're worried about your warranty, but once your car is off warranty, do you want it making noises or running like it should? It's nice to want a sound, but after a while you might just get tired of the sound. All the sounds of the car blending together. Wondering if your bov is leaking or if another sound started. Not that you shouldn't get one, but is a sound really worth your money and possible problems?

    peace

  8. #3037
    Banned emosubaru's Avatar
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    i stand corrected

  9. #3038
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    Originally posted by hippy78
    Most people think the stock bov is pretty cool. Even if people say that aftermarket bov's won't void your warranty, you don't wanna be the one going to subaru with the dead engine. They might just say that it had something to do with your malfunctioning aftermarket bov and that you have to pay to fix the engine(it's happened to more then one person). Not that you're worried about your warranty, but once your car is off warranty, do you want it making noises or running like it should? It's nice to want a sound, but after a while you might just get tired of the sound. All the sounds of the car blending together. Wondering if your bov is leaking or if another sound started. Not that you shouldn't get one, but is a sound really worth your money and possible problems?

    peace
    your argument doesn't make a whole lot of sense.. sounds all blending together? it doesn't happen. I have a TBE, hks bov, not-so-quiet axxis ultimates, and prodrive springs (providing plenty of extra road noise). you can pick out each and every noise. I also have gear whine to some extent. less now that i've changed to a different tranny fluid. these sounds don't mix together.

    if you're worried about the bov leaking, just look at your boost gauge. you'll notice a drop as well as reduced performance. if you're paranoid about leak, go hks. by design it doesn't leak.

    functionality? you run rich to the tune of a sneeze's amount of gas on shifts. meh. i've recently begun to wonder how big the difference really is from bov to bpv. when you vent back to the intake charge pipe, you're releasing pressurized air into a big open environment. that air will immediately drop in pressure as it hits that vacuum. it takes a brief moment for the ecu to react as it is, so what is the actual difference in the amount of oxygen between lifting off at full throttle using a bpv, and using a bov? that is, simplistically, what makes you run so rich.

    now i'm VERY curious. i get the feeling nobody has the testing equipment or want to furnish me with an answer though
    05 STi...not stock

  10. #3039
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    Different BOV question

    My current mods are listed below. I am upgrading my headers, intake, and going w/a txs FMIC. I had an RFL bov but sold it and went back to stock. What a difference. My stock one was much better. I however want to know that with 300whp do I need to change my bov to an aftermarket one ? I am going to be running approx. 18 psi from my vf 22.....

    any thoughts ? thanks
    L.I.S.C #00 (Treasurer)
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    387whp and 371 whtq. 93 Octane

  11. #3040
    Registered User Snowvert's Avatar
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    I would say it's more based on the psi you are running instead of what power you are laying down as different dyno's read differently.

    most say the magical number is about 20psi, but if yer going with a fmic and looking for 300whp, I would pick one up myself. it wouldn't hurt and i'd recommend the blitz, it's a nice piece.
    03 wrx - 300whp/270wtq
    Originally posted by zoophagy
    The people that work there are, for the most part, retards. I used to work there.

  12. #3041
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    If you think that a bov won't leak cause it's called hks, you might just be wrong. If you think that hks works any differently then any other bov(other then having two vents), you might be wrong. If you think that your boost goes down just cause you have a bov leak, or that you will notice the performance difference, you might be wrong. If you think that noone out there checked there a/f ratio while running an atmospheric bov, you're wrong(cause I have and so have a ton of other people). If you think there's no difference between at atmospheric bov and a bypass valve, you're also wrong.

    It isn't all about running rich though, cause most people wouldn't care less if they ran a little rich between shifts. It would make a nice sound if I took the tires off the wheels and drove, or the exhaust pipes off the engine, or the intake filter off the intake. I don't remove parts from my car (like many people) without there being some type of benifit. In general, removing parts from the car(like recirc hose) results in a noise being made. That doesn't mean I'm gonna start going around my car seeing what parts I don't need(like the recirc hose). If you want a sound, I'll sit next to you while you drive and scream between shifts. You could also get an electrical device that does it instead of me. It would do the same thing as an aftermarket bov without any drawbacks and probably cost less at the same time. I mean if you're gonna be a ricer you mine as well do it right. Or, you could waste $200+ on a part that came with the car and remove another that you already paid for(the recirc hose). For a lot less, you can put a knife in your tire and make another noise. It wouldn't have the possiblility of screwing up your engine either......

    peace

  13. #3042
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    Originally posted by hippy78
    If you think that a bov won't leak cause it's called hks, you might just be wrong. If you think that hks works any differently then any other bov(other then having two vents), you might be wrong. If you think that your boost goes down just cause you have a bov leak, or that you will notice the performance difference, you might be wrong. If you think that noone out there checked there a/f ratio while running an atmospheric bov, you're wrong(cause I have and so have a ton of other people). If you think there's no difference between at atmospheric bov and a bypass valve, you're also wrong.


    the basic design of the hks makes it so it will not leak. in other bov's the stopper in the bov is held shut by a combo of spring tension and positive manifold pressure routed through that vacuum line. in the hks the stopper is held shut by both the boost pressure coming from the IC and the combo of positive manifold pressure from the vacuum line and spring tension. the more you boost, the tighter the hks holds. the reported problems with the hks leaking have all been at the C clamp on the adapter, but that's only with supra guys.

    the nature of a leaking bov is that less boost will make it to the throttle body, and thus the cylinders. most people tap a line in the manifold for their boost gauges, not the peaky line coming off of the bpv/bov. with it tapped at any of those places you'll notice a variance in boost pressure immediately. I noticed it when my forge bov leaked at -2psi (negative two psi). and yes, with all that other stuff going on i could tell that happened because it made a very distinct sound.

    the hks does not have two vents. i'm not sure how you came up with that. it's a sequential bov, meaning the stopper opens in increments, but that's about it. I really don't know where you got that from...

    It isn't all about running rich though, cause most people wouldn't care less if they ran a little rich between shifts. It would make a nice sound if I took the tires off the wheels and drove, or the exhaust pipes off the engine, or the intake filter off the intake. I don't remove parts from my car (like many people) without there being some type of benifit. In general, removing parts from the car(like recirc hose) results in a noise being made. That doesn't mean I'm gonna start going around my car seeing what parts I don't need(like the recirc hose). If you want a sound, I'll sit next to you while you drive and scream between shifts. You could also get an electrical device that does it instead of me. It would do the same thing as an aftermarket bov without any drawbacks and probably cost less at the same time. I mean if you're gonna be a ricer you mine as well do it right. Or, you could waste $200+ on a part that came with the car and remove another that you already paid for(the recirc hose). For a lot less, you can put a knife in your tire and make another noise. It wouldn't have the possiblility of screwing up your engine either......

    peace
    now you're just not making any sense again. how does this relate in any way to having a bov? are we going back to that whole "too many noises" thing? or are you assuming a certain level of modification? honestly there isn't a whole lot left for me to modify (power-wise) beyond a turbo swap and the necessary reflash. remove the filter? tires? what the hell are you babbling about? remove the exhaust pipes? lol you seriously are making no sense...
    05 STi...not stock

  14. #3043
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    it's kind of a combo of cfm and psi. with the vf22 you're looking to be venting a LOT more air between shifts. the stocker may hold fine, but i'm not sure. good valves to look into are the greddy type S and hks sseq. i'm NOT entirely sure if the greddy type S will hold what you will run. you might need a stiffer spring for it. I know if you go too much higher you will need to get the type R, but my gut tells me you don't need that at 18psi on a vf22.

    take heed, my gut is decently large. it knows a thing or two even if my head doesn't

    you can go ahead and get an adapter welded on your intake piping so you can use your oem bpv (bypass valve) with your new setup. it may hold fine. the worst that will happen that way is that you'll be able to run various bov's with wrx adapters (kinda nice, but more expensive in the long run by just a tiny bit).

    the SAFEST route is defintely just going that latter route. thing is, that may be unnecessary. it's def. an option and all up to you. i've seen posts where people running vf22's held more boost more reliably with a good bov as opposed to the factory bpv. I've also seen posts where people swapped and it made no difference.
    05 STi...not stock

  15. #3044
    Banned hippy78's Avatar
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    I'm currently stock waiting for the warranty to end, so this gives me time to think about what I want to do, Iv'e read in a few threads that Bov decreases the engine performance when the turbo is stock, why is that ? My understanding was that the bOV opened to let air into the turbo when you're not on the throttle to keep the turbo spooling.

    While we're on the subject what's a everyday turbo , that I don't have to worry about detonating my motor with? Responses greatly appreciated.

    - thanks
    ......
    I don't mind not having a performance increase I just really like the sound for some reason.....and do you know of an everday turbo ?
    Everyone can do whatever they want(obviously). I'm confident that most seasoned wrx owners would say that especially on a stock car the money is better spent elsewhere(on anything but a bov basically). If you really want a noise when you shift, you hooking an air horn to the clutch pedal is a better way about doing it(imo). If the horn doesn't work normally, chances are that your turbo won't break. You might even be able to have more fun with an air horn then a bov.

    peace

    ps - I wonder how many bov owners are wishin they had air horns?

  16. #3045
    Registered User 13secwrx's Avatar
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    I do like the rfl..If i place the proper amount of washers do you think this is a good BOV ?
    L.I.S.C #00 (Treasurer)
    02 Wrx...465whp and 472 whtq. 100 Octane
    387whp and 371 whtq. 93 Octane

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