Expected boost drop with compression drop?

DSG2003Mach1

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4v mod motor so no variable cam timing etc. Lets say EVERYTHING else in the combo is the same - you went from a 10:1 motor to a 9.5:1 motor. They did whatever a "competition valve job" might be and everything else is exactly the same. The car made 15# before with the procharger, how many psi would you expect/guestimate now?
 

robvas

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Any chance it would just be the % difference of the new cylinder volume?
 

Deceptive

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My understanding is that boost should be the same. You have not removed any restrictions or at least anything significant. The CR should not make any difference in the restriction it just makes you less efficient.


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DSG2003Mach1

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Had some belt slip issues and just been dicking around with the car but time to sort it out one way or another. Time to put it on the dyno for a full pull and see what it does.

Car has a 10% OD since when it made 15# along with going to a griptec blower pulley.
 

01yellercobra

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It's been a while, but the second time I built my 5.3 I bumped compression from 9.0 to 9.5. I think it ended up somewhere 9.4ish. But anyway, I don't remember the boost changing between the two compression ratios. It was same intake, exhaust, and cams the whole time.
 

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