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copbait73 copbait73 is offline
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Join Date: Nov 2003
Location: Chesterfield IN
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Originally Posted by gsmith660 View Post
My motor is already running at the ragged edge of what I think a mag case can take so I know not having a BOV adds wear to the turbo but does it stress the motor or does the press. and stress get stopped at the butterfly?
No stress to the engine proper outside the intake system (hoses, o-rings, brackets). Right now you are deadheading the boost against a closed throttle and the turbo is going into surge (the aerodynamic area to the left of the diagonal line on a compressor map). This can cause the thrust bearing to fail or in turbos other than modern Garrett break the locking nut torque. There are many factors involved in predicting if or when a failure will occur, boost level being significant. I don't consider your mild boost to be significant.

All turbochargers pass a thrust bearing qualification test. In fact running in surge is required just to generate a compressor map. All turbocharger companies say regular OPERATION in surge will fail the bearing system. I would not expect any healthy turbo to fail the first time it surged however it’s common to get a sound like this when a turbo has a catastrophic failure.

All said, you will retain (a) sound if you just add the BOV and vent to atmosphere. It’s best you do this. This eliminates the risk of surge as your turbo will not see deadheading against the closed throttle. As for increased boost response by recycling air back into the compressor inlet? In street operation that stuff is mostly BS the factory used to hide the facts: 1) CIS demands it for proper operation, 2) MOST people are put off by unusual sounds......even turbo whine!

In my book a turbo engine should chirp or wheeze on shift plus whine up and down with boost.

Last edited by copbait73; 02-27-2010 at 05:15 PM..
Old 02-27-2010, 11:19 AM
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