But the rod will be significantly smaller than the bore. eg a 4" bore
will likely have an 1-1/2" rod. Which would give you 12.56 square inches
out, and 10.79 square inches on the return stroke.

Eric R Snow wrote:
On 6 Apr 2005 09:31:21 -0700, "monkers" wrote:


The two diameters I mentioned are the piston dia. How do I tell the
bore size , as it is different than piston dia. correct?


The bore size is only a few thousandths different than the piston dia.
In fact, if a cylinder is called out as a 4" cylinder then the bore
will be 4 inches and the piston slightly smaller.
ERS