Quote:
Originally Posted by Dominik
old dog:
as for the better heat disappation (note: "better") isolated hot spots on the ring or wall would be moved around up during rotation allowing hot spots to meet cooler ones?
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Since the piston goes up and down the cylinder, the rings are always coming into contact with a different area of the cylinder wall. I would expect the temperature to be the hottest where the most fuel is burned, which would be toward the top. I am doubting that there is a big temperature difference radially at any given plane in the cylinder. Of course how the water jackets are constructed could make a difference. Siamese bores might have hot spot in a line. I don't know.
Since two cycles run with pinned rings, I'm having a hard time buying that rings need to rotate for heat dissipation. I doubt that some engineer sat down with the intention to cause rings to rotate for a good reason. Rather I believe there was no perceived need to prevent rotation, when there are no ports, and it was just left to chance. Simply do not design in extra costs unless it is necessary.