"The BIG BOV thread" (Where all bov question threads get merged) - Page 659

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 The Boxman when i'm in low boost, and i let off the gas, there is a fluttering ...

  1. #9871
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    Quote Originally Posted by The Boxman View Post
    when i'm in low boost, and i let off the gas, there is a fluttering noise coming from the passenger side of my car.
    i have a GFB BOV, that is fully adjustable, and i took the intake silencer, and i'm trying to figure out what is wrong.
    YouTube - Engine Flutter
    that's my car. you can hear the flutter really good at the last shift.
    that's compressor surge.
    What it is, is the BOV spring pressure is set too high, or the vacuum signal to it, sucks (no pun intended.)

    Either way, it's not healthy, by any means, especially for your turbo. What's happening, is, air is being forced backward when you close the throttle plate (and the bov isn't opening), causing the pressurized air to make its way back through the IC, and to the compressor housing, pushing the wheel (trying to) opposite of it's rotation..
    Imagine the stress on the CHRA when the turbine side is still being turned the proper way, by exhaust gases, yet the compressor is trying to follow suit, but meets this backpressure resistance..
    Not healthy.
    Fix it. Soon.
    Rogan o_0
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  3. #9872
    Registered User WRXDrummer's Avatar
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    Quote Originally Posted by The Boxman View Post
    but it only happens in super low boost, and when i'm boosting really hard it blows off like normal, instead of making that weird noise, and sometimes it will blow off and then make the flutter.
    That is called compressor surge and it is REALLY BAD. That will kill your turbo. It happens only in low boost because it doesnt have enough pressure to trigger the BOV, so the air surges back into the turbo.

    Seriously, take it off asap or you will soon hear a lot more bad noises from the passenger side (ie turbo side) of your car.

    edit: I was beaten to the punch. Dang!

  4. #9873
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    Quote Originally Posted by The Boxman View Post
    but it only happens in super low boost, and when i'm boosting really hard it blows off like normal, instead of making that weird noise, and sometimes it will blow off and then make the flutter.

    TAKE OFF THE BOV
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    BOV and MAF issue comment

    I'm not sure where to start this thread but feel free to move if needed.

    Let me start by saying I am by no way an expert in the WRX area but I do however know a lot about mustangs and how superchargers and turbos work on them so in theory they should work very similiar. On a mustang we have 3 different ways to monitor air blow thru MAF, drawl thru MAF and speed density. It's a big no no to put a BOV/bypass after the blow thru meter because of the unmetered air so what we do in the mustang world is switch to a blow thru MAF and put the meter up closer to the throttle body and put the BOV before the MAF therefore all the air is metered.

    That being said is it possible to switch a WRX/STI to a blow thru configuration rather then a stock drawl thru? If so that is a possible solution to the issue people are having with BOV.

    Let me know what ya think.

    Alain
    2008 Subaru WRX

    1998 Mustang GT 9.00@151mph
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  6. #9875
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    No that wouldn't really work. The Subaru engines and computers are a lot more sensitive than the Mustang engines and computers.
    Scott
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    Quote Originally Posted by teflon_jones View Post
    No that wouldn't really work. The Subaru engines and computers are a lot more sensitive than the Mustang engines and computers.
    wrong. Theres tons of people running blow-thru on bigger turbos.

    However, it would require going with a FMIC & a complete custom retuning of the MAF tables along with all the normal fuel, timing, & boost.
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  8. #9877
    Registered User jeffmm06's Avatar
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    Seems like a lot of work just a a PSHHH. Unless your running a setup that requires it of coarse.
    2005 WRB WRX "was" STAGE 2

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    Quote Originally Posted by 98SILVERSTANG View Post
    That being said is it possible to switch a WRX/STI to a blow thru configuration rather then a stock drawl thru? If so that is a possible solution to the issue people are having with BOV.

    Let me know what ya think.

    Alain
    That is correct, Alain. That layout would work.

    Quote Originally Posted by teflon_jones View Post
    No that wouldn't really work. The Subaru engines and computers are a lot more sensitive than the Mustang engines and computers.
    False

    Quote Originally Posted by testes1010 View Post
    wrong. Theres tons of people running blow-thru on bigger turbos.

    However, it would require going with a FMIC & a complete custom retuning of the MAF tables along with all the normal fuel, timing, & boost.
    I was gonna say the exact same thing.. See,, J, you can teach an old dog new tricks.

    Quote Originally Posted by jeffmm06 View Post
    Seems like a lot of work just a a PSHHH. Unless your running a setup that requires it of coarse.
    That's usually the idea behind these thoughts.. I've tossed the idea around A LOT lately.. I've got a ton of little issues, that are likely the result of a big setup, BOV, draw-thru MAF, etc..
    Rogan o_0
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  10. #9879
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    Quote Originally Posted by testes1010 View Post
    wrong. Theres tons of people running blow-thru on bigger turbos.

    However, it would require going with a FMIC & a complete custom retuning of the MAF tables along with all the normal fuel, timing, & boost.
    You can do anything you want to an engine and make it work once you start modifying that much. You have to assume the OP was talking about a relatively stock setup.

    Quote Originally Posted by Rogan View Post
    False
    Sorry, but I don't agree. If it were that easy, then why aren't people doing it? The fact is that you can do pretty much anything you want to an engine but either you need to engineer/test the heck out of it, or accept the problems that will be caused. So sure, you could do what the OP suggested, but it's not that simple. It'll require a lot of tweaking/engineering/testing. I have to assume the OP was talking about just bolting it up to a stock car.
    Scott
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  11. #9880
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    more people aren't doing it, because of just that: It ISN'T easy. It's a lot of work/time/tuning to get it to operate.

    And I rarely assume anything.

    And even in your reply:
    No that wouldn't really work. The Subaru engines and computers are a lot more sensitive than the Mustang engines and computers.
    you basically said it wouldn't work, due to engine/computer sensitivity. It isn't that, at all; stock or modified.
    Last edited by Rogan; 05-20-2008 at 07:35 PM.
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    Thanks guys for the input.

    No it's not something your everyday person would do on their car but for someone looking to continue modding then it would probably be something that should be considered. IMO when ever you have a modified setup be it increasing Boost, supercharging a N/A combo or simply changing cams you should have a custom tune or map done for the car.

    I currently run a DFI Gen VII standalone in my mustang with hours upon hours of dyno/track time just to fine tune the current setup. It's not cheap but I don't think a car tuned in CA is going to act the same as a car in FL and that's essentially what your doing when you download a MAP from someone else.

    The computer maybe more sensitive but nothing a custom map couldn't correct. Believe me you can do alot with a stock computer.


    Alain
    Last edited by 98SILVERSTANG; 05-21-2008 at 06:00 AM.
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    Quote Originally Posted by teflon_jones View Post
    You have to assume the OP was talking about a relatively stock setup.
    Re-read his OPs post. He's referring to supercharged & turbo charged Mustangs using Blowthru setups & Speed Density....neither which are 'relatively stock setups'.
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  14. #9883
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    Quote Originally Posted by teflon_jones View Post

    Sorry, but I don't agree. If it were that easy, then why aren't people doing it? The fact is that you can do pretty much anything you want to an engine but either you need to engineer/test the heck out of it, or accept the problems that will be caused. So sure, you could do what the OP suggested, but it's not that simple. It'll require a lot of tweaking/engineering/testing
    What doesn't take alot of tweaking?An intake?Bigger injectors?The problem is it's alot of $$$$ for most as they don't know how to tune for a blow throw.Lot of money to spend just to run a kazoo....
    Last edited by Donkey; 05-21-2008 at 04:29 PM.
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  15. #9884
    Registered User Kmlacrosse's Avatar
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    Cant you ajust your bov to release pressure at a lower psi? after all if bovs break your turbo at low boost then why are they even on the market? secondly i used to have a turbosmart supersonic bov and it ****ed up my idle and casued excessive backfire. i switched to an aps bov and now im problem free. the only dif is its very very quit.

  16. #9885
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    what's the APS one like?
    pic??
    Rogan o_0
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    '01 Dodge 2500 CTD 6-holed hand-shaker - 3850# dual disk - 900 lb/ft - SOLD
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