"The BIG BOV thread" (Where all bov question threads get merged) - Page 696

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; yes perfect way to put it , and yes im a noob =/ but we learn something new everyday Originally ...

  1. #10426
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    yes perfect way to put it , and yes im a noob =/ but we learn something new everyday


    Quote Originally Posted by Rogan View Post
    that's not even close to what it means, or how to do it..

    1. loosen the nut
    2. adjust the screw (in = TIGHT, out = LOOSE).. to further expand on that, the tighter the tension is set, the more pressure it takes to open the BPV.
    3. once adjusted to where it needs to be, tighten the nut to keep the screw from moving during time/vibration.

    Note: a BOV set too loose, or 'soft', can actually sit 'open' during high-vacuum situations, such as idling, or light-throttle cruising.

    Summary: the screw/adjuster does not make a BPV or BOV louder or more quiet, it makes the piston/diaphragm easier/harder to open.

    The volume is determined by how much "boost pressure" is being expelled/rerouted, as well as the actual design if the BPV/BOV. 5psi will be a lot softer sounding than, say, 20psi.
    Think of yourself exhaling.. normal breathing is very quiet, because a minimal amount of 'pressure/volume (as in mass, not audible)' is being expelled. After a sprint, your breathing is much louder, because you are now expelling a greater volume/pressure of air.

    understand, now?

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  3. #10427
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    Quote Originally Posted by Rogan View Post
    that's not even close to what it means, or how to do it..

    1. loosen the nut
    2. adjust the screw (in = TIGHT, out = LOOSE).. to further expand on that, the tighter the tension is set, the more pressure it takes to open the BPV.
    3. once adjusted to where it needs to be, tighten the nut to keep the screw from moving during time/vibration.

    Note: a BOV set too loose, or 'soft', can actually sit 'open' during high-vacuum situations, such as idling, or light-throttle cruising.

    Summary: the screw/adjuster does not make a BPV or BOV louder or more quiet, it makes the piston/diaphragm easier/harder to open.

    The volume is determined by how much "boost pressure" is being expelled/rerouted, as well as the actual design if the BPV/BOV. 5psi will be a lot softer sounding than, say, 20psi.
    Think of yourself exhaling.. normal breathing is very quiet, because a minimal amount of 'pressure/volume (as in mass, not audible)' is being expelled. After a sprint, your breathing is much louder, because you are now expelling a greater volume/pressure of air.

    understand, now?
    I usually set adjustable BPVs/BOVs up to where the piston/valve stays closed at idle.. blip the throttle, and when the engine decels, the valve will open. Once it's returned to idle, the piston/valve closes up again. Once Ive got it there, I give it about 1/4-1/2 turn more, to help alleviate the tendency to 'push open' under high boost, which is pretty hard for it to do, considering there's boost pressure on the back-side of the piston/valve, helping to force/hold it closed in accelerated situations.



    edit: I can't believe I actually quoted myself...
    Rogan o_0
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  4. #10428
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    i know that a bov is bad for a wrx or sti, but y do almost ever srt-4 and jetta or gti have them? does there stock bov not recirculate? so they can put an aftermarket one on?

  5. #10429
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    Quote Originally Posted by joefman714 View Post
    i know that a bov is bad for a wrx or sti, but y do almost ever srt-4 and jetta or gti have them? does there stock bov not recirculate? so they can put an aftermarket one on?
    An SRT4 is a speed-density setup, IIRC.

    The MkIII / MkIV VWs are MAS setup, but the ECUs are much more tolerant of varying changes, where the Subaru ECU is far more sophisticated than the previous mentioned counterparts.
    Rogan o_0
    '96 Dodge 2500 CTD @ 40psi - over 700 lb/ft TQ, 7" stack, and 5speed! - SOLD
    '01 Dodge 2500 CTD 6-holed hand-shaker - 3850# dual disk - 900 lb/ft - SOLD
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  6. #10430
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    Quote Originally Posted by Rogan View Post
    An SRT4 is a speed-density setup, IIRC.

    The MkIII / MkIV VWs are MAS setup, but the ECUs are much more tolerant of varying changes, where the Subaru ECU is far more sophisticated than the previous mentioned counterparts.
    ohh ok thanks

  7. #10431
    Wrinklechops
    Just for the record, it was THIS post, out of all the other ones on the entire internet that made me buy my GFB hybrid. Had it for about 4 months now and I love it. So thanks! If you're still around on this forum, that is...seeing how ancient this thread is...lol

  8. #10432
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    Cool

    Although he probably wouldn't admitt it, I'll bet blarg would be happy that he helped.
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  9. #10433
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    Quote Originally Posted by lundholm08 View Post
    Just for the record, it was THIS post, out of all the other ones on the entire internet that made me buy my GFB hybrid. Had it for about 4 months now and I love it. So thanks! If you're still around on this forum, that is...seeing how ancient this thread is...lol
    Now this might make you think twice:

    Real blow-off valves are used in high boost (20+ psi) to prevent the momentary rise in boost pressure of up to 50 psi from blowing out intercooler side tanks or popping off hoses when the throttle is shut. But at normal boost levels (under 18 psi) we can use the rush of over pressure to prevent our turbocharger from stalling all the time when we lift the throttle. This helps the turbo make better throttle response and boost quicker in real world conditions.
    Enter the $35 by-pass (or priority valve) concept first developed on the AUDI rally cars and first introduced in the Audi Quattro Turbo and Porsche 944T. The very first Subaru EJ20 in 1989 also had this type valve. Your WRX has one also and we want you to keep it on your motor, unless there comes a reason to change it out.
    The compressor by-pass valve is connected from the turbocharger compressor high pressure side (intercooler) back through to the low pressure side (the intake section) just ahead of the turbo compressor. When you close the throttle to shift gears this valve opens. It makes a loop of air back into the inlet with the boost spike of air pressure in the intercooler. Everyone has probably heard a blow-off valve go 'whoosh'. Well, we want that 'whoosh' to go right back to work keeping the turbo compressor wheel from slowing down. Instead of spending money on an aftermarket blow-off valve just to make noise, we leave the factory priority valve in place. Why?
    The loop air flow effectively puts the turbocharger into a no load condition and the wheel keeps spinning. Under this very low load condition the high pressure air in the intercooler blows into the intake via the by-pass valve and pin-wheels compressor impeller. When the throttle is opened again, the turbine wheel is still spinning at a relatively high rpm and will go right back to work putting out boost.
    Without this by-pass valve feature the compressor/turbine wheels tend to stall between shifts and it takes longer to build up boost again after each shift. This is also true when the throttle is lifted in a corner for any reason. When you get back in to the gas, the by-pass valve actually is slow in closing and lets the turbine free wheel for an eye blink, bringing the boost on much quicker. Why any driver would spend money and give this throttle response advantage in away for the sake of noise of a blow-off valve is almost funny to think about. Yet, many shops will sell you a blow-off valve with a straight face. But, now you know. This is a classic case of, 'If it ain't broke, don't fix it".

    I could tell you that by adding curb feelers to my car it made it spool faster because my butt dyno said so.Are you going to believe me?I hope not.Not saying blarg's situation with his BOV swap did or didn't happen but when I make moddifications to my car I use a logging program to distinguish between real tanglable results and the "placebo effect" of my butt dyno.Unless you have a true way of measuring somewhat scientificlly then mabe it just "feels" faster because you have to justify the $200 dollars you just spent.Trust me,I've been there
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  10. #10434
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    BOV causing backfiring?

    Almost a month ago I installed a GFB hybrid bov, everything went smoothly and it was an easy installation. Now though every once in a while it will backfire. from what i know about backfiring it is the explosion of unburned fuel or air in the exhaust system. now installing the bov does richen the mixture somewhat so is this a possible cause for backfiring? thanks

  11. #10435
    Moderator Donkey's Avatar
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    This is a no brainer since you already know a BOV causes excessive richness between shifts.You already answered your own question.Not to mention the BOV stickies at the top of the page.
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  12. #10436
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    Quote Originally Posted by donkey View Post
    this is a no brainer since you already know a bov causes excessive richness between shifts.you already answered your own question.not to mention the bov stickies at the top of the page.
    +1
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  13. #10437
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    Quote Originally Posted by doubled177234 View Post
    now installing the bov does richen the mixture somewhat so is this a possible cause for backfiring? thanks
    Yes. It is likely the only cause.
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  14. #10438
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    recirc

    purpose over show

  15. #10439
    Wrinklechops
    Thanks Donkey, and yes, I feel sort of dumb for spending over $200 on something that isn't really helping me... and could have spent that $ on some new Eibach springs or something instead.... but with regard to the well written article you provided, doesn't the GFB hybrid BOV that I have work just like the stock one, with recirculating air back into the intake/turbo? I haven't noticed a lack of performance, at the very least. Not claiming that I noticed an increase either though, for sure...

    Anyone want to buy a BOV? Lol I could put that $ to use elsewhere on my car...

  16. #10440
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    So after reading this...I really want to take my hybrid bov off and put my BPV back on....I had it on for a while after I put the intake and exhaust on and you still hear the "cool" sound...its just not quite as loud....I got my car tuned with the hybrid on...I am only pushing about 18psi..if I put my BPV back on will this cause any problems...since it was tuned with the bov?
    Quote Originally Posted by Donkey View Post
    Now this might make you think twice:

    Real blow-off valves are used in high boost (20+ psi) to prevent the momentary rise in boost pressure of up to 50 psi from blowing out intercooler side tanks or popping off hoses when the throttle is shut. But at normal boost levels (under 18 psi) we can use the rush of over pressure to prevent our turbocharger from stalling all the time when we lift the throttle. This helps the turbo make better throttle response and boost quicker in real world conditions.
    Enter the $35 by-pass (or priority valve) concept first developed on the AUDI rally cars and first introduced in the Audi Quattro Turbo and Porsche 944T. The very first Subaru EJ20 in 1989 also had this type valve. Your WRX has one also and we want you to keep it on your motor, unless there comes a reason to change it out.
    The compressor by-pass valve is connected from the turbocharger compressor high pressure side (intercooler) back through to the low pressure side (the intake section) just ahead of the turbo compressor. When you close the throttle to shift gears this valve opens. It makes a loop of air back into the inlet with the boost spike of air pressure in the intercooler. Everyone has probably heard a blow-off valve go 'whoosh'. Well, we want that 'whoosh' to go right back to work keeping the turbo compressor wheel from slowing down. Instead of spending money on an aftermarket blow-off valve just to make noise, we leave the factory priority valve in place. Why?
    The loop air flow effectively puts the turbocharger into a no load condition and the wheel keeps spinning. Under this very low load condition the high pressure air in the intercooler blows into the intake via the by-pass valve and pin-wheels compressor impeller. When the throttle is opened again, the turbine wheel is still spinning at a relatively high rpm and will go right back to work putting out boost.
    Without this by-pass valve feature the compressor/turbine wheels tend to stall between shifts and it takes longer to build up boost again after each shift. This is also true when the throttle is lifted in a corner for any reason. When you get back in to the gas, the by-pass valve actually is slow in closing and lets the turbine free wheel for an eye blink, bringing the boost on much quicker. Why any driver would spend money and give this throttle response advantage in away for the sake of noise of a blow-off valve is almost funny to think about. Yet, many shops will sell you a blow-off valve with a straight face. But, now you know. This is a classic case of, 'If it ain't broke, don't fix it".

    I could tell you that by adding curb feelers to my car it made it spool faster because my butt dyno said so.Are you going to believe me?I hope not.Not saying blarg's situation with his BOV swap did or didn't happen but when I make moddifications to my car I use a logging program to distinguish between real tanglable results and the "placebo effect" of my butt dyno.Unless you have a true way of measuring somewhat scientificlly then mabe it just "feels" faster because you have to justify the $200 dollars you just spent.Trust me,I've been there

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