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Compressor Surge or BOV

Discussion in 'Forced Induction' started by TurboRex90, May 25, 2009.

  1. TurboRex90

    TurboRex90 Golden EG

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    Ok so im sure anyone that hears a car go by with a turbo, you love the sound of the flutter "tu tu tu tu tu". Although those with any knowledge in the forced induction field are aware of a thing called compressor surge or "cavitation".

    For those who do not know what compressor surge is:

    Compressor Surge- A condition caused by compressed intake air caught between the compressor wheel and closed throttle plates. When you get off the throttle after a burst of acceleration, the plates close but the compressor wheel may still be sending compressed air into the system. If the compressed intake charge cannot flow through the throttle plates, it will flow back to the compressor, causing it to spin "backwards", which could result in bearing damage.

    Some of us know that certain Blow Off Valves can imitate this imfamous sound, one known example ise the Differential Bypass Valve or DV for short, which usually come on VW 1.8T.

    An example:
    [​IMG]


    The question that i want to know, and many other turbo enthusiasts may want to know is,
    Is it possible to modify a standard BOV to produce the infamous "flutter", without causing severe damage, if any to the turbo without using a DV?

    Thanks!

     
  2. awptickes

    awptickes unimpressed by you VIP

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    No.

    The flutter/sneeze/bwoosh/etc. is the compressor cavitating. It can destroy bearings in the turbo, and it tends to at higher boost levels. BOVs also make the compressor work harder, because it's essentially a leak in the system. They create a pressure imbalance, and the compressor wheel stops spinning a bit before the turbine wheel; a BOV stresses the turbine/compressor shaft.

    Ask yourself why every factory-designed system recirculates....

    Personally, I hate that sound. It sounds like fingernails on a chalk-board mixed with screaming babies.
     
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  3. TurboRex90

    TurboRex90 Golden EG

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    Some days i like the sound and some days i cringe at the noise. I never knew that the BOV put stress on the turbo, thanks for some new information ^_^.

    Where exactly would i have to recirculate my BOV to if i decided to do so?
     
  4. Matts96HB

    Matts96HB . Moderator VIP

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    Run a line off the end of your BOV (the end that normally vents to the atmosphere) and run that back to the intake tube for your turbocharger (where the filter would be, NOT where it goes into the charge piping). You may have to get a fitting depending on what BOV you're running.
     
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  5. awptickes

    awptickes unimpressed by you VIP

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    Exactly.

    What you want the recirculating valve to do is equalize the pressure around the turbocharger's compressor. Many factory superchargers do the same thing just because it's so damned efficient.
     
  6. disableddan

    disableddan Crazy Insane

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    Wow, I guess you do learn something new every day! :D
    I kinda wondered about recirculation. This knowledge will be applied to my turbo project :D +rep!!!!!!!!!!!w00t!!


    EDIT) erm- could you clarify about where the recirculation should enter the charge pipe pre-compressor? "where the filter would be"?> Thanks!
     
    Last edited: May 26, 2009
  7. awptickes

    awptickes unimpressed by you VIP

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  8. efhondakid

    efhondakid My name is Byron. VIP

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  9. awptickes

    awptickes unimpressed by you VIP

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    I'm tempted to neg-rep you for that one. :p
     
  10. TurboRex90

    TurboRex90 Golden EG

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    Bahaha.... but i like that noise. :(

    But i guess since im converting my setup into a "sleeper" i may want to invest in this idea. :rolleyes:
     
  11. awptickes

    awptickes unimpressed by you VIP

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    Personally, I'm one for setups that try to hide the turbo whine too. :D Make them think all you've got is a ricer-fart-cannon. :D

    Then, while cruzing on the highway, some jackass in a VW (or in amerika: a big lifted pickup) comes up, tries to pull on you, and all you have to do is flex your ankle. That's tons of fun.
     
  12. TurboRex90

    TurboRex90 Golden EG

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    how do you hide the whine??
     
  13. awptickes

    awptickes unimpressed by you VIP

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    Insulate exhaust pipes, exhaust manifold, Intake and intake plenums, charge piping, intake piping, and use a quality air filter. Also, if you use a really cheap fart-can-muffler it helps too.
     
  14. TurboRex90

    TurboRex90 Golden EG

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  15. awptickes

    awptickes unimpressed by you VIP

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    Yeah.
     
  16. Matts96HB

    Matts96HB . Moderator VIP

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    Recirculated system FTW. Drove my car today, it will be getting recirculated. Love Synapse because they already have a fitting on the end that is suitable for a hose and clamp. :D
     
  17. TurboRex90

    TurboRex90 Golden EG

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    Yeah, lucky you.
     
  18. Matts96HB

    Matts96HB . Moderator VIP

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    Not lucky, just know where to put the money when it comes to a turbo build... Everywhere.
     
  19. TurboRex90

    TurboRex90 Golden EG

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    Well your lucky you HAD the money to put it everywhere. lol
     
  20. Matts96HB

    Matts96HB . Moderator VIP

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    Not lucky there either, I work hard for it.
     
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