So, sometimes I look at my traffic and links here, and the post about horsepower ratings gets consistent traffic, and is linked by a number of discussions all over the charts – even appliance repair forums. This one, though, is from the Tesla Owners page, and it’s awesome. So I’m linking it. Sort of a meta-link, since he links me. The Wonders of the Interwebs.
Seriously, it’s probably the most concise, to the point, and factually correct explanation of power ratings, torque ratings, how gas and electric motors generate power, and even the historical significance of the convention. Just say “no” to the comments, though. I guess even the Tesla forum gets its trolls.
Enjoy: WHAT IS HORSEPOWER RATING?
For electric motors the power is often rated as to how much power you can supply to them safely so that engineers can design systems around them. Public didn’t really come that much in contact with electric motor details and engineers were happy. Electric motors are VERY efficient compared to ICE and the difference between input and “output power” isn’t that huge – it is kind of like a sales tax.
Internal Combustion Engines are way more complicated beasts and are horrendously inefficient when compared to electric motors. They leak and squirt that input power everywhere. They can’t even process it equally efficiently across various speeds. Because of this their “input power” was never really measured in power units but rather in their fuel consumption. Even that is rarely stated – we mostly see various “good efficiency” fuel consumption numbers that don’t relate to the power listed. The HP rating that we get for ICEs is the “output power”.