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Year of HP ratings change

bill_w

bill_w

Advanced Contributor
Does anyone know when OMC changed their HP ratings from crank output to prop output? I know it was in the 80's, just not sure exactly what year.

thanks in advance
 
This HP output thing is something that will get kicked around until the end of time.

However, I was around and associated on the 1962 electric shift engines when they were new, just rolling off the assembly line. At that time OMC had quite a promotional film available which was available to the dealerships... and the dealership I was with just happened to have one to impress the customers.

One statement that was made in that film which I will never forget was somewhat of a argument statement against Mercury which was that the horsepower ouput of OMC's engines was measured at the propeller whereas Mercury's was at the crankshaft. This was in 1962.
 
OK, that was 1962. What happened in the mid 80's when the 115's became 90's, etc. I've been told that somewhere around 86 or 87 the change was made to meet BIA standards. Wasn't this also the time that OMC bought out the loop charged engines? Bottom line is, I have 3 115 hp OMC's. They are 1980, 1985, and 1991. I have been told that the '91 is equal to an '85 140 hp. If so, I'll get the '91 fixed (it needs a cylinder bored) because I'd like the extra ponies..I'm currently running the 1980.
 
The OMC went prop rated about 1982-83 so either of your 115hp in the 1985 or1991 year will work as the 115/140 went from flatback to potbelly exhaust
 
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