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Discussion Starter · #1 ·
I have noticed alot of questions being asked that people have begun by saying "sorry for the noob question." In an effort to put as much information as possible in one place I am starting this thread for people to post up what they think is important turbo tech. I will also be hoping around to other car forums/sites to gather up as much good info as I can.

To start here are some basic BOV tech facts and opinions.

There are multiple ways a BOV can work the most typical are a pusher type (like turboXS) or a puller type (like HKS). The advantage of puller is it tends to stayed sealed better under high boost due to the pressure acting to hold it closed. Pullers tend to be more expensive (generally).

The purose of a BOV is to prevent cavitation, over boosting and maintain good AFRs. Cavitation is caused when the throttle body closes between shifts while the turbo is continuing to spin; attempting to push more air into an already charged air line. The effect can severly deminish the life of your turbo and can even (in extreme cases) break fins off your compressor.

There has been some speculation that "wa ta ta ta" (vs PSSSSSHHH) type BOVs aren't doing their job and still allow cavitation. I leave it up to you.

I won't go into why you should stick to a recirc on our cars simply because it has been covered already. The point of a non-recirc or Vent To Atmosphere is for carburated (sp?), non-factory turbo, or even factory turbo with aftermarket ECM. A recirc on these cars can cause a suden lean condition acting opposite of VTA on our cars.

Here is some good info from my last car forum containing some basic turbo knowledge.

http://my.is/forums/forumdisplay.php?f=72

Here is some more stuff, a little more advanced and not all pertanant to the MS6 but still good.

http://my.is/forums/forumdisplay.php?f=61
 

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The purose of a BOV is to prevent cavitation, over boosting and maintain good AFRs. Cavitation is caused when the throttle body closes between shifts while the turbo is continuing to spin; attempting to push more air into an already charged air line. The effect can severly deminish the life of your turbo and can even (in extreme cases) break fins off your compressor.
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I may be wrong, but I don't think turbocharger impellers can cavitate. Cavitation occurs when a pump is spinning in a liquid and the pressure along the blades drops too low. That casues the vapor point of the liquid to drop and subsequently vaporizes the liquid in a localized spot. This creates a huge pressure differential that eventually collapses violently and causes damage to the blades. Since a turbo impeller isn't spinning a true liquid, what vaporizes to cause cavitation?

Are you thinking of the pressure wave generated by the closing throttle plate? Sorry to nitpick.
 

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Discussion Starter · #3 ·
I may be wrong, but I don't think turbocharger impellers can cavitate. Cavitation occurs when a pump is spinning in a liquid and the pressure along the blades drops too low. That casues the vapor point of the liquid to drop and subsequently vaporizes the liquid in a localized spot. This creates a huge pressure differential that eventually collapses violently and causes damage to the blades. Since a turbo impeller isn't spinning a true liquid, what vaporizes to cause cavitation?

Are you thinking of the pressure wave generated by the closing throttle plate? Sorry to nitpick.
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Cavitation is a widely used and accepted term used to refer to the turbulance acting on a turbo compressor resulting from an overcharged intake track. Your definition also applies but it has nothing to do with turbo's.
 

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"Cavitation is a general term used to describe the behaviour of voids or bubbles in a liquid. Cavitation is usually divided into two classes of behaviour: inertial (or transient) cavitation and non-inertial cavitation. Inertial cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Such cavitation often occurs in pumps, propellers, impellers, and in the vascular tissues of plants. Non-inertial cavitation is the process where a bubble in a fluid is forced to oscillate in size or shape due to some form of energy input, such as an acoustic field. Such cavitation is often employed in ultrasonic cleaning baths, and will also be observed in pumps, propellers etc."

Strait from Wikipedia.

MY 2 cents
 

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Cavitation is a widely used and accepted term used to refer to the turbulance acting on a turbo compressor resulting from an overcharged intake track. Your definition also applies but it has nothing to do with turbo's.
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Okay, fair enough. I've just never seen cavitation used in that context. Thanks for the explanation.
 

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Discussion Starter · #6 ·
Okay, fair enough. I've just never seen cavitation used in that context. Thanks for the explanation.
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Yeah it isn't the hydrodynamic definition but it refers to a similar force acting upon the compressor wheel. If you google "turbo cavitation" you can see how widely the term is used.
 
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