blow-off question
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This is a discussion on blow-off question within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; When i replaced my stock bypass valve for an HKS SSQ blow-off, did i sacafice my bypass valve? does the ...

  1. #1
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    blow-off question

    When i replaced my stock bypass valve for an HKS SSQ blow-off, did i sacafice my bypass valve? does the hks act as a bypass to??
    help please!

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  3. #2
    cnk
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    The HKS vents to atmosphere unless you got the recirc kit. The stock BOV vents back to the intake. You didn't sacrifice your bypass valve, you're just venting to a different location now. Some people notice a decrease in performance with aftermarket BOV's though. . .it's mostly just a sound mod. But as long as you like it, just do what you want.

    Calvin

  4. #3
    Registered User SonicYellowWRX's Avatar
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    yeah it tends to cause a rich idle... makes sense if you think about it. there are BOV's that vent both into the atmosphere and recirculate it to prevent that rich idle.
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    Registered User blarg's Avatar
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    yup...there are several

    I run a GFB 50/50 that completely eliminates any idle problems
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    Quote Originally Posted by Blarg
    go f*** yourself

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    yikes, i think i have noticed a little decrease in performance since i installed it. this is becasue aftermarket blow offs are intended to relieve turbos that are producing alot more horsepower than stock was designed? am i right? with a few mods, i should cancel out the loss in performance casued by the ssq

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    cnk
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    The main reason for the decrease in performance is because the ECU already knows how much air is in the system from the MAF sensor. When the stock BOV goes off, it assumes that air is going back into the intake and thus gives it the appropriate fuel. Since aftermarket BOV's vent to atmosphere, the ECU would be giving the engine more fuel to compensate for the expected air that isn't there, thus causing a rich mixture.

    Not sure if a bigger turbo would necessarily eliminate this, but it may make it less noticeable. The stock BOV is capable of handling 20.5psi IIRC though so an aftermarket BOV may not even be needed unless you plan on running more boost than that.

    Calvin

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    Registered User blarg's Avatar
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    50/50 valves split the outgoing air...since the 2 pathways are connected, if the motor creates a negative pressure (because it needs air) all the air actually goes back to the intake until the negative pressure is gone...this elimintaes the problem of running rich...in fact under some conditions you won't hear the BOV sound because the air isn't escaping to the atmosphere.

    the benefit? well...um....it makes a cool noise sometimes....and I guess it could be argued that the valve opens and closes a little faster and the vent it bigger so it dumps the pressure faster and reduces turbo lag. I noticed a little difference, but I have to admint that it probably wasn't the best way to spend $200.
    ScoobyDMC #009 - making dirty jokes since before you were making dirty diapers.
    Quote Originally Posted by Blarg
    go f*** yourself

  9. #8
    Registered User SonicYellowWRX's Avatar
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    Originally posted by blarg
    50/50 valves split the outgoing air...since the 2 pathways are connected, if the motor creates a negative pressure (because it needs air) all the air actually goes back to the intake until the negative pressure is gone...this elimintaes the problem of running rich...in fact under some conditions you won't hear the BOV sound because the air isn't escaping to the atmosphere.

    the benefit? well...um....it makes a cool noise sometimes....and I guess it could be argued that the valve opens and closes a little faster and the vent it bigger so it dumps the pressure faster and reduces turbo lag. I noticed a little difference, but I have to admint that it probably wasn't the best way to spend $200.
    yeah, well when you boost beyond 20 psi you will be glad you had gotten it.
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  10. #9
    Registered User blarg's Avatar
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    I"m actually about to get a spare turbo from a wrecked WRX that'll probably go out for that upgrade service where they bore it out and put it a bigger compressor or something...so I guess i will be....sooner than I thought.
    ScoobyDMC #009 - making dirty jokes since before you were making dirty diapers.
    Quote Originally Posted by Blarg
    go f*** yourself

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