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Old 03-18-2005, 08:30 PM
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How do you figure compression?

I have a 454 that is rebuilt. What I want to know is how do I figure out what the compression ratio is? I didn't build the motor I bought it redone in a truck and the guy didn't know the answer. I plan on doing head work and a cam but would like to know what I am starting with.

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Old 03-18-2005, 08:34 PM
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comp ratio

Pick your combo out of the list. It will give you comp ratio. SRP Pistons
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Old 03-18-2005, 10:42 PM
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compression ratio

volumn of the cylinder, plus the volumn of the unswept area divided by the unswept area.

Unswept area: the relief from the top of the piston to the deck of the block, the combustion chamber volumn, the volumn of the valve reliefs in the pistons, and the volumn of the cylinder opening in the head gasket.
Suptract from that the volumn of the dome, if you have domed pistons.

Cylinder volumn + Unswept Area Volumn divided by the Unswept area volumn.
Volumn of the cylinder is Pi X R squared X H.
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