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Old 07-07-2011, 04:20 PM   #11 (permalink)
Diesel_Dave
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White Whale - '07 Dodge Ram 2500 ST Quad Cab 2wd, short bed
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Quote:
Originally Posted by Frank Lee View Post
I'm not so sure diesels have less friction. In spite of turning lower rpms, they typically have longer strokes; interestingly enough there are many gassers that run 1000-1200 ft/mn piston speed while the two stroke diesels anyway are running 1700! The ring pack is the largest single contributer to friction so higher piston speeds must lead to higher friction.

Plus they have heavier rotating/reciprocating parts which add friction.
Now that I think about it some more, it might not be fair to make a blanket statement that diesels have lower friction. It probably depends a lot more on the specific engine design. Plus, diesels have higher cylinder pressures (which would increase friction).

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