"The BIG BOV thread" (Where all bov question threads get merged) - Page 652

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; That is imposible to do! The math alone, well you know.......

  1. #9766
    Registered User bcyb1029's Avatar
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    That is imposible to do! The math alone, well you know....
    Tuned by Jorge at P&L, 240.83whp 239.60wtq at 14.8psi on 2.0L with stock td04 (But doesn't run)

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  3. #9767
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    Need Bov Help

    my friend just sold me his hks bov (just the bov), and im wondering is the flange and the plug the only thing i need? is there a website that sells the flange? and the plug?
    Last edited by sheckephano; 04-25-2008 at 11:06 PM.

  4. #9768
    Registered User Death To Ricers's Avatar
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    You made a mistake by buying the BOV. They are not good for our cars.
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  5. #9769
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    Quote Originally Posted by Death To Ricers View Post
    You made a mistake by buying the BOV. They are not good for our cars.
    why, i heard if i increase the psi, hks bov help reduce turbo surge.

  6. #9770
    Registered User Death To Ricers's Avatar
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    Quote Originally Posted by sheckephano View Post
    why, i heard if i increase the psi, hks bov help reduce turbo surge.
    Blow Off Valve FAQ: Read if you are thinking of buying one! - Newbies & FAQs - NASIOC

    Read this. It will explain all of you're questions.
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    Quote Originally Posted by RayfieldsWRX View Post
    You could vote to fix me a sammich.

  7. #9771
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    ibtmerge!
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  8. #9772
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    Quote Originally Posted by sheckephano View Post
    why, i heard if i increase the psi, hks bov help reduce turbo surge.
    what kind of car do you have? are you getting 'turbo surge?'
    "I do well to be angry, even unto death."
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  9. #9773
    Geriatric Ginger Mod Rogan's Avatar
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    Quote Originally Posted by sheckephano View Post
    why, i heard if i increase the psi, hks bov help reduce turbo surge.
    I get compressor surge, sometimes under light loads, but that's because of a big turbo, and a 12psi spring in my BOV..

    stock subaru turbos, be it a td04, or a vf, will not surge, as the bpv has a light spring tension, thus opening easily.

    Surge is not an issue.
    Rogan o_0
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  10. #9774
    Would Never, Ever Say Something Bad About an Admin's Mom SonicWagon's Avatar
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    Quote Originally Posted by sheckephano View Post
    my friend just sold me his hks bov,
    If I were you I would kick your friends ass, and spit in his eye socket.
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  11. #9775
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    Quote Originally Posted by jma_1000 View Post
    what kind of car do you have? are you getting 'turbo surge?'
    07 rex, my friend said that might be surge

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    i think you need a new friend

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  13. #9777
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    Quote Originally Posted by wrxtreme06 View Post
    i think you need a new friend
    agreed.

    "what" makes him think you have "Compressor surge"?

    Does he know what compressor surge is? Do YOU know what compressor surge is? It appears that neither does.

    Surge is the situation when the compressor "spits out" more air than the engine can swallow, which causes a backup of air at the intake and it actually creates reverse-flowing pressure waves that can be very damaging to the turbo.
    Another situation is when the throttle plate slams shut (let off the throttle) and all that boost, coming down the pipe, suddenly has nowhere to go. This is when the BPV opens (since vacuum is present on the diaphragm), giving the air a place to go.. Picture you riding a Big Wheel ( old man reference) down a hallway at 20mph.. Just before to leave the hallway and enter the room at the end, someone slams the door shut.. WHAM youve got nowhere to go but backward, as you slam into the door.. But, just as you reach the slammed door, a side door opens, and you quickly steer into that room, and come to a smooth decel, and make your way to the back of the line, to try down the hallway again.

    Picture that same scenario but with 30 people on bigwheels, nose-to-tail, doing the same thing.. without that side door opening, you all are gonna get backed up, until noone else can enter the hall, so you head out the way you came in (through the compressor outlet..)
    problem is, the compressor outlet is trying to still shoot people in.. so you abnormally try to reverse the compressor wheel. This is the bad part, because at the other end of that wheel shaft, is another wheel, not being impeded, and still trying to spin the correct direction. See where I'm going with this? Hold a straw by each end and twist one end opposite of the other. Same thing tries to happen to the turbo, but can result in expensive consequences.

    You want to avoid surge at all costs.


    Turbos move Volumes of air, at a rate.. The OE bpv will handle quite a bit of volume. When this volume has been reached, you start to get a backup (hall theory), which begins the surge issue.


    I can go much deeper into details, and make it more of a technical post, but I'd rather not, right now. At least you are now a little more educated with surge, or at least now have an idea. Now go out, and find you some new friend(s).
    Last edited by Rogan; 04-26-2008 at 12:21 PM.
    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
    '97 Dodge 3500 CTD DUALLY built Auto - 40psi boosties - 750 lb/ft

  14. #9778
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    Quote Originally Posted by sheckephano View Post
    07 rex, my friend said that might be surge
    so what kind of turbo are you running? larger than stock? what kind of dp do you have on?

    let me know just how far off i am on this:

    you have cobb apv2 with stage 2 map (w/LC, FTW!)
    you have catless dp
    you have either boost creep, spike, or both

    sound familiar? what you need is a bcs and tune, not a bov. and follow advice of above posters, about beating up your current friend (after educating him on his stupidity) and get a new one.
    "I do well to be angry, even unto death."
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  15. #9779
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    Quote Originally Posted by Rogan View Post
    agreed.

    "what" makes him think you have "Compressor surge"?

    Does he know what compressor surge is? Do YOU know what compressor surge is? It appears that neither does.

    Surge is the situation when the compressor "spits out" more air than the engine can swallow, which causes a backup of air at the intake and it actually creates reverse-flowing pressure waves that can be very damaging to the turbo.
    Another situation is when the throttle plate slams shut (let off the throttle) and all that boost, coming down the pipe, suddenly has nowhere to go. This is when the BPV opens (since vacuum is present on the diaphragm), giving the air a place to go.. Picture you riding a Big Wheel ( old man reference) down a hallway at 20mph.. Just before to leave the hallway and enter the room at the end, someone slams the door shut.. WHAM youve got nowhere to go but backward, as you slam into the door.. But, just as you reach the slammed door, a side door opens, and you quickly steer into that room, and come to a smooth decel, and make your way to the back of the line, to try down the hallway again.

    Picture that same scenario but with 30 people on bigwheels, nose-to-tail, doing the same thing.. without that side door opening, you all are gonna get backed up, until noone else can enter the hall, so you head out the way you came in (through the compressor outlet..)
    problem is, the compressor outlet is trying to still shoot people in.. so you abnormally try to reverse the compressor wheel. This is the bad part, because at the other end of that wheel shaft, is another wheel, not being impeded, and still trying to spin the correct direction. See where I'm going with this? Hold a straw by each end and twist one end opposite of the other. Same thing tries to happen to the turbo, but can result in expensive consequences.

    You want to avoid surge at all costs.


    Turbos move Volumes of air, at a rate.. The OE bpv will handle quite a bit of volume. When this volume has been reached, you start to get a backup (hall theory), which begins the surge issue.


    I can go much deeper into details, and make it more of a technical post, but I'd rather not, right now. At least you are now a little more educated with surge, or at least now have an idea. Now go out, and find you some new friend(s).
    i know what surge is, and my isnt dumb. my friend did some motorswaps and turbo upgrades. he said it might be it.

  16. #9780
    Geriatric Ginger Mod Rogan's Avatar
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    Quote Originally Posted by sheckephano View Post
    i know what surge is, and my isnt dumb. my friend did some motorswaps and turbo upgrades. he said it might be it.
    my isnt dumb?

    I never said you were dumb. Bottom line, a BOV isn't going to help your situation, whatever it may be. unless you're running a 30R or equivalent, and 20+ psi boost, I highly doubt the stock bpv is being 'over-powered'..

    Is the vacuum line in good shape, no leaks, and operational? has the stock bpv failed? I cant recall ever hearing of that, but doesn't mean it cant.. If the stock bpv isn't working, then yes, you could be getting a little bit of surge..
    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
    '97 Dodge 3500 CTD DUALLY built Auto - 40psi boosties - 750 lb/ft

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