Horsepower ratings ?
- Thread starter ATVGUY
- Start date
Old Hickory
New Member
Mercury and johnson both began rating their motors at the prop in the mid 80's. The best I can gather is Johnson began in 1982 and Mercury began in 1985. Japanese/asian motors have always rated their motors from the prop. Consensus is it has only made about a 10% difference or loss.
The reason for rating from the prop vs flywheel is due to to several factors; 1) gear ratio in the lower will change the HP as well as 2) the type of prop mated to the OB. If you change either of these from factory; HP will change. And last 3) Imported OB's initially had the reputation early on for being able to push a boat faster w/ less HP. Made the american OB's look like gas guzzling; oil burning clunkers. American mfg's going to prop rated HP made comparison easier and demonstrated motors were much closer in HP ratings than the publics perception. Also took away the imports claim ..... "ours is better because we can do more w/ less"
The reason for rating from the prop vs flywheel is due to to several factors; 1) gear ratio in the lower will change the HP as well as 2) the type of prop mated to the OB. If you change either of these from factory; HP will change. And last 3) Imported OB's initially had the reputation early on for being able to push a boat faster w/ less HP. Made the american OB's look like gas guzzling; oil burning clunkers. American mfg's going to prop rated HP made comparison easier and demonstrated motors were much closer in HP ratings than the publics perception. Also took away the imports claim ..... "ours is better because we can do more w/ less"
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