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sparcebag

Horsepower question

6 posts in this topic

OK old motors are rated at the head for HP?

Newer motors at the prop RIGHT?

So a old 25HP is now rated what? how bout a old 35HP

Do they lose or gain HP as rated for new? And how much of a gain or loss with a standard prop?

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Approximately 10% is lost in the gears. So, an old 25 would be about a net 221/2 hp at the prop give or take. A new 25 produces 25 at the prop.

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nice bit of info to know. Next hp question ive been wondering about is the comparison between 2 stroke and 4 stoke.

A 2 stoke and 4 stroke, lets use a 150 hp for comparison, rated the same right? But between the two do they perform differantly.

I would think the 2 stroke may have more tourqe, or differant power bands. Just wondering on the differant performances between the two.

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Thanks Boatfixer even tho I'm gettin older I always have questions...I know a little about everything and even more about nothin.

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I have an '80 Johnson 15hp I bored .030" over. Anybody have a dyno??!! wink Just kidding

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