When Did OMC start Measuring Hp at Prop.

[OptsyEagle]

Does anyone remember when Evinrude/Johnson started measuring their Hp at the propeller as opposed to measuring it at the powerhead? What model year did this transistion take place?

 

[BoatBuoy]

Re: When Did OMC start Measuring Hp at Prop.

The change didn't occur for all models in a single year. "The first OMC outboard was changed in 1985. But not all were changed in 1985. The 115 crossflow in 85 was called the 115 although it was identical to the 1984 140 crossflow."...Dhadley, who knows more than most about OMC.

 

[OptsyEagle]

Re: When Did OMC start Measuring Hp at Prop.

Would you know if a 1987 9.9Hp Evinrude was measured at the prop. or powerhead?

 

[steelespike]

Re: When Did OMC start Measuring Hp at Prop.

Boy a 20% difference on the 140 to 115 sure sounds like a lot to me.Seems to me they may have detuned the 140 to a 115 instead of increasing the 115 to make at the prop power.
It's pretty much academic on the 9.9 you wouldn't be able to tell the difference in performance without a tach and gps.I can tell you I believe the 9.9 and 15 appeared in 74 and are 13.2 cu in at least to 89. The 9.9 is rated at 5,000 to 6,000 rpm to 88 and changed to 5,500 to 6,500 in 89 perhaps changed to prop hp at that point?The 15 was rated at 5,500 to 7,000 at least through 89.