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Old 10-28-2012, 10:48 PM
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Originally Posted by wwilliams181 View Post
and the loss of cylinder pressure due to the added overlap.
Let me help you out here in case there are any newbies reading this and misunderstand what you have written.

There is little or no cylinder pressure at overlap. The piston is coming up to TDC on the exhaust stroke and has evacuated the cylinder of exhaust gases from the previous power stroke. The intake valve is just beginning to open. So, we have two valves open and cannot possibly have any cylinder pressure.

Cylinder pressure is determined by the static compression ratio of the motor combined with the intake valve closing point after bottom dead center.
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