Piston Velocity, stroke and rod length

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01-06-2003 | 12:24 PM

#11

ursus

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Quote:

Originally posted by blown1500
You must leave room for a proper ring package, but I usually add up all the numbers and go for the longest rod I can conveniently get. Next, the longer the rod, the better the side loading on the piston skirt. If you built two engines just alike except the rod length, and ran them for a long period of time under load, the one with the longer rod would show the lesser cylinder wear. It MAY show more power due to less piston weight due to shorter skirts, less rock in the cylinder(better ring seal) etc.

Yes This is basically the point I was trying to make. There is/was a lot of misconceptions about piston velocity/acceleration and rod length. You will get more power/less wear with a longer rod/short skirt combo because the reduced angle causes less side loading of the piston, less load = less friction = more power & less wear. Longer rods do NOT make more torque because of changes in piston velocity because the piston velocity simply doesn't change very much. Piston Velocity is for all practical purposes determined soley by stroke.