"The BIG BOV thread" (Where all bov question threads get merged) - Page 781
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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 castro702 Im wondering what type of bov I should use on my 2003 wrx top intercooler Sent ...

  1. #11701
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    Quote Originally Posted by castro702 View Post
    Im wondering what type of bov I should use on my 2003 wrx top intercooler

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  3. #11702
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    My 08 wrx is stock outside of the ap (stage 1 93 oct.), cobb cai and turbo xs rfl (I am aware many people don't like these ) I put on last night. My question is what to look for on a datalog to see if there is compressor/boost surge? I think there may be a little but not at WOT. Usually it happens around 2,000- 3,000 rpms if let off the throttle quickly, it sort of sounds like a horse. What is really throwing me off is I've read a lot of threads saying that the td04 is so small there will only be minimal if any surge; can anyone shed some more light on this? Will be running and hopefully posting datalogs later on tonight once I'm out of work. Sorry if this has been answered/asked already but I haven't found anything that really helped me out.

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    Quote Originally Posted by jraz08wrx View Post
    My 08 wrx is stock outside of the ap (stage 1 93 oct.), cobb cai and turbo xs rfl (I am aware many people don't like these ) I put on last night. My question is what to look for on a datalog to see if there is compressor/boost surge? I think there may be a little but not at WOT. Usually it happens around 2,000- 3,000 rpms if let off the throttle quickly, it sort of sounds like a horse. What is really throwing me off is I've read a lot of threads saying that the td04 is so small there will only be minimal if any surge; can anyone shed some more light on this? Will be running and hopefully posting datalogs later on tonight once I'm out of work. Sorry if this has been answered/asked already but I haven't found anything that really helped me out.
    Took some datalogs last night and the bov is causing boost leak, peaking at 10.8 psi @ 4666 rpms. Cleaned it today will drive with it to work tonight and log a few more pulls if the results are the same it will be coming off and the stock bpv will be going back on tomorrow and I'll run logs with that and post all the log results for viewing.

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    Gotta quick question for the pros.

    For ****s and giggles, did the quick run around the block with the stock bov running atmospheric. 2013 limited model. With the recirc hose plugged, I got on it and nearing 4500rpm I could hear the stock valve opening to release pressure under boost.

    Should the stock bov bypass air that early? Or is that just because it was no longer recirc-ing?

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    Quote Originally Posted by CoolGuyRx2 View Post
    Gotta quick question for the pros.

    For ****s and giggles, did the quick run around the block with the stock bov running atmospheric. 2013 limited model. With the recirc hose plugged, I got on it and nearing 4500rpm I could hear the stock valve opening to release pressure under boost.

    Should the stock bov bypass air that early? Or is that just because it was no longer recirc-ing?
    Go to the first page and you can read my BOV FAQ... It'll shed a lot of light on what's happening. If I do say so myself... I did a good job keeping the technical bullsht to a minimum and just explain how the whole BOV system works.

    That big hose you took off is connected to the inlet tube about 4 inches from the compressor of the turbo. So as you were hitting boost, you heard the whoosh of the air being sucked by the turbo, and you were allowing unmetered (post MAF) air into the inlet... Which caused a severe lean condition.

    I wouldn't do that again! I hope you didn't cause any damage

    If you correctly plugged that hose (please tell me you did!) then you shouldn't have heard any sound on throttle, but off throttle or part throttle you might have heard sound... That is normal.
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    Quote Originally Posted by CoolGuyRx2 View Post
    Gotta quick question for the pros.

    For ****s and giggles, did the quick run around the block with the stock bov running atmospheric. 2013 limited model. With the recirc hose plugged, I got on it and nearing 4500rpm I could hear the stock valve opening to release pressure under boost.

    Should the stock bov bypass air that early? Or is that just because it was no longer recirc-ing?
    You can't run the stock BPV to atmosphere, it doesn't work that way. Read before you destroy your motor.
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    It was plugged....and don't worry..it was a test...back to stock after one pull...no detonation

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    Quote Originally Posted by CoolGuyRx2 View Post
    Gotta quick question for the pros.

    For ****s and giggles, did the quick run around the block with the stock bov running atmospheric. 2013 limited model. With the recirc hose plugged, I got on it and nearing 4500rpm I could hear the stock valve opening to release pressure under boost.

    Should the stock bov bypass air that early? Or is that just because it was no longer recirc-ing?
    For anyone reading this thread looking for BOV questions/answers, do not do this. This could cause severe damage. This is not the same as having an atmospheric BOV (which would cause a rich condition). As Sinister mentioned, this would cause a lean condition, which is way more dangerous. Neither are good, but going too lean makes things go boom.

    CoolGuy, I would recommend that you do no further tests such as this for poops and giggles, unless you are looking for a way to ruin your car. No offense intended at all, but unplugging random engine components to see what happens is a very bad idea. Especially if you don't know what the result will be.

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    Wow man...thanks for the flogging....engine fine, no harm or foul.
    ...although I did notice something peculiar.....the outlet of the stock bov has a massive restriction before the outlet. It goes from about pinkie size to the just over 1-inch discharge. Took a mild Demel to it and opened it up....easily doubled the inside size of the discharge....seems to recover a little quicker.....without the placebo effect ;-)

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    Quote Originally Posted by CoolGuyRx2 View Post
    Wow man...thanks for the flogging....engine fine, no harm or foul.
    ...although I did notice something peculiar.....the outlet of the stock bov has a massive restriction before the outlet. It goes from about pinkie size to the just over 1-inch discharge. Took a mild Demel to it and opened it up....easily doubled the inside size of the discharge....seems to recover a little quicker.....without the placebo effect ;-)
    Good idea. I'm sure the engineers must have missed that one!
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    Click image for larger version. 

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    Big difference....

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    ....went Type-S anyway....holds and responds great....Digging into that old parts bin...lol...lovin the Rexxi!!
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    Last edited by CoolGuyRx2; 02-16-2014 at 11:39 PM.

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

    Quote Originally Posted by CoolGuyRx2 View Post
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    Big difference....
    That looks like you did a wonderful job. I'm sure it improved the function markedly. I doubt those jagged edges affected the piston at all. Should let subaru engineers know?
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    Quote Originally Posted by Sinister View Post
    Good idea. I'm sure the engineers must have missed that one!
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