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Use this calculator to see what the effect of bore, stroke, rod length, cam timing, compression ratio, boost pressure and altitude is on your dynamic compression ratio. Of the variables, the most important is cam timing which has a dramatic effect on your "dynamic" as opposed to your static compression ratio. The more "overlap" your cam has, the lower your "actual" as opposed to your static compression ratio will be. This is one area you can easily change.
Another consideration is rod length and it's effect on the engine's output. Changing the rod length will affect the piston location in the bore relative to cam timing everywhere except at TDC and BDC thus changing the dynamics of the engine.