Flywheel or Prop Hp?

[Bobobob]

What year did they stop rating Outboards at the flywheel and start rating them at the prop?

Also what is the basic conversion from flywheel Hp to Prop Hp? 5 hp? 10 hp?

Curious to know for HP conversions for future boat purchases.

 

[bassboy1]

Re: Flywheel or Prop Hp?

Well, I can tell ya that a motor loses about 10% of its horsepower from the flywheel to the propshaft. Also, it was sometime in the mid eighties when the ratings changed from flywheel to prop. Course, I don't know the exact year.

 

[Joe Reeves]

Re: Flywheel or Prop Hp?

That question gets asked from time to time, and the answer varies from brand to brand. That being said.........

Back in 1962 (yes, I can remember that far back), OMC had a film available to dealerships promoting their engines. One of the features that was really stressed was the fact that the horsepower was measured at the propeller on all of their models..... and this horsepower at the propeller was a feature according to OMC that did not exist with the Mercury engines.... a big selling point of course.

I see no reason why OMC or Bombardier would change that feature but if they did, I'm not aware of it.

 

[Big Keepers]

Re: Flywheel or Prop Hp?

I was told that my 1979 Evinrude was most likely rated at the flywheel. Its a 175hp. I was also told that at the prop it probably only puts out about 130 hp.

 

[Joe Reeves]

Re: Flywheel or Prop Hp?

I should think that Bombardier would have that knowledge available, one way or the other. Should I have time, I'll see what I can find.

 

[jauguston]

Re: Flywheel or Prop Hp?

Did Evinrude change from rating at the flywheel to rating at the prop or the other way around? I was told my '85 8hp was the same engine as the 7.5 and the only difference was how the power was rated. For that to be true it would have to be rated at the flywheel and the 7.5 was rated at the prop. Is that a reasonable assumption or is the difference that supposedly the 8 is rated to run at 5000-6000 instead of 4500-5500 rpm.

Jim

 

[wbeaton]

Re: Flywheel or Prop Hp?

It would make more sense that they increased the rpm to get more hp.

I'd really like to know the answer to this question once and for all. I hope you find something, Joe.