Thread: Engine RPM
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Old 12-04-2014, 12:21 PM   #15
River Cruiser
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City: UMR MM283
Vessel Name: Northern Lights II
Vessel Model: Bayliner 3870
Join Date: Jan 2013
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Quote:
Originally Posted by timjet View Post
Ski is far more knowledgeable than me on this topic but I seem to recall a discussion on boatdiesel that ended with the conclusion that over propped/overloaded is still the case regardless of the RPM.

I agree with this. The govenor is going to add more fuel to maintain rpm between a correctly propped vessel and one that is over propped. Just because it's not against the pins doesn't mean it's not overloaded. And unlike a engine in a dozer or scraper that is intermittently overloaded during its life, a engine is continuously overloaded in a over propped boat. There is less harm at RPMs below WOT but the effects of overloading do not disappear. A exhaust gas temperature gauge I'am sure would show higher temps at the same rpm between the correct prop and being over propped because of the increase of fuel to maintain rpm. I doubt any of us will kill our engines by being over propped by a small amount because we're not going to put that many hours on them, but a owner who ignores being over propped is probably ignoring other items in his engines maintenance and the cumulative effect may substantial shorten engine life.
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