Horsepower question

[sparcebag]

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?

[boatfixer]

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.

[Wade Joseph]

Yep, your both correct.

[croixflats]

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.

[sparcebag]

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

[LanceJ]

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