General question about my 45hp mercury

[ugadawg187]

So i have a 88 mecury 45hp classic 50 & ive been wondering why it says that. Basicly its the same as a 50hp merc??? Also this motors hp is rated at the hub correct? So if i was to buy a 70's model merc 50hp mine would have more power? Ive been told during the 70's the motors were rated at the motor then sometime during the 80's they started rating them at the hub correct?

 

[05GlastronSX]

Re: General question about my 45hp mercury

Yes, that is correct. Outboard manufacturers changed the power rating from the crank to the prop in 1988 i believe was the year. Therefore, your 50 hp merc is rated at 50 hp at the crank, but 45 hp at the prop. All outboards 1988 and up are rated at the propeller shaft, hence why your motor is rated at 45 hp, not 50. There is roughly a 10%-15% loss in power in horsepower when it is transferred from the crank to the propeller. This loss obviously comes from the friction of turning the lower unit gears and prop, heat, ect. My 150 h.p prop rated mercury, its actually about 165-170 at the crank, whereas an older 150 (before 1988, like the old inline 6 motors) were 150 hp at the crank, and maybe 135 at the prop.

 

[tashasdaddy]

Re: General question about my 45hp mercury

correct. the change was to inform the buyer how much output he was actually buying.

that is like buying a motor with a jetdrive, use to be they would say it was 90hp. but realistically, it is a 90/60, 90 hp at the powerhead, and only 60 hp output at the jet outlet.