How is horsepower measured??

[haddles]

Is the horsepower rating given on the cowl a reflection of the crank or prop output? Is it the same with inboards and outboards? Do all manufacturers use the same method?

 

[Dunaruna]

Re: How is horsepower measured??

HP is a universally recognised method to rate the output of ANY motor, in fact, it is directly related to the measurement of electrical power (760watts = 1 HP).<br /><br />Originally (300 years ago), it was determined that the average horse could pull 1000lbs a distance of 22ft in one minute, this became the standard mearsurement known as 'one horsepower'. Now it is done with computers/algorithims and dynomometers.<br /><br />Back in the 60s'/70s' & 80s', all motors were measured via the flywheel, now all you will see is prop figures.

 

[haddles]

Re: How is horsepower measured??

What got me thinking was those briggs and stratton outboards that look like a mower engine stuck onto a leg. I figured their power would be measured at the crank as they would do for other applications of their motors. Since we have no license or registration required for 6 and 4hp respectively here I was curious as to where it was measured.

 

[seahorse5]

Re: How is horsepower measured??

Every outboard in the US manufactured after 1998 has to have an EPA emission sticker on it. The tag also tells the motor's power rating in metric units called kilowatt-hours. By multiplying the KW/HR by 1.341, you get the rated horsepower.

 

[timmathis]

Re: How is horsepower measured??

Torch