Piston Dome Volume??

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Feb 14, 2006 | 08:21 AM

61driver

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From: Tn

Piston Dome Volume??

Please correct me if I am wrong, but a flat top piston with valve reliefs would have a - (minus) dome volume when used for compression ratio calculations. The technician I talked to only confused the math even more. thanks in advance..

Ray

Feb 14, 2006 | 09:55 AM

CFI-EFI

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From: The Top of Utah

Bassackwards. A dome reduces the ccs of the combustion chamber, so the dome volume is subtracted (-). A valve notch is a volume to be added (+).

RACE ON!!!

Feb 14, 2006 | 11:59 AM

SWCDuke

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Yes, and the piston mfg. should have the specs. For example, the flat top, four notch OE 327 pistons have negative 5.4cc "dome volume" and the forged, domed SHP pistons are plus 5.3 cc.

Here's an easy to use online CR calculator:

http://www.csgnetwork.com/compcalc.html

Make sure to enter the "dome volume" and deck clearance with the proper algebraic sign.

Duke

Feb 14, 2006 | 05:00 PM

61driver

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From: Tn

Thanks for the reply. That is actually the calculator I was using..I think I have it figured out. We'll see if she runs.

Ray

Feb 14, 2006 | 11:10 PM

Corvette Kid

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From: Good health is merely the slowest possible rate at which one can die

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Yes, my current flat tops have a -6cc volume.

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