What is “Peak Horsepower”?

The “Peak” Horsepower Game and Why We Do Not Play It

The other day I received a call from a potential customer who was doing his research on motorcycle dryers before deciding which one to purchase. While some may not like people like this guy because of all the questions they ask, I personally enjoy having a dialogue with someone who is truly seeking information.

We discussed the “Peak HP” that is advertised by one of our competitors. Now as a design engineer with well over 10,000,000 electric motors sold in my career, I know a thing or two about horsepower, peak horsepower, developed horsepower, brake horsepower and whatever else you want to call it.

And I am here to tell you that choosing a motorcycle dryer or any other motorized product based on “Peak Horsepower” is a bad decision. Companies that rely on selling “Peak Horsepower” are selling you something that doesn’t smell too good. Years ago, the vacuum cleaner people tried this with peak and developed horsepower in their ads until some government agency accused them of misleading ads. Now they advertise “amps” as an indication of size (this is completely misleading too since a poorly designed motor will consume more amps).
A few years ago, the air compressor market was selling “peak” horsepower too and the same thing happened to them legally. It is misleading. It is NOT truth in advertising.
Lately the portable spa manufacturers have advertised “6 BHP” pumps and “12 HP Spas!” More misleading stuff to try to trick the potential buyer into thinking they are getting something they are not.

I will try to keep this as basic as possible. Horsepower is defined as 746 watts of power. Assuming a motor is 75% efficient (which is actually on the high side!), the motor will consume 1000 watts for every horsepower that goes out the motor shaft. The difference between 1000 and 746 (254 watts) is lost in the form of heat. That is why all electric motors get hot. To get 1000 watts with 120 volt AC power, takes 8.3 amps (1000 divided by 120). So for every one horsepower, it takes about 8.3 amps of power at 120 volts. Therefore a 4hp dryer would use 4 x 8.3 = 33.3 amps and an 8 hp dryer would use 8 x 8.3 = 66.4 amps.

Yet they list their 4 Peak HP dryer at 9.5 amps and their 8 Peak HP dryer at 19 amps. How can this be? Has the laws of physics been rewritten for motorcycle dryers?

Now I am not trying to disparage my competitor in any way; I just think that assuming motorcycle owners are stupid isn’t too smart at all.

To sum this up: Ignore HP in your comparison for the best motorcycle dryer (or compressor, vacuum cleaner, drill press or portable spa!). To properly compare two dryers, look at the CFM (cubic feet per minute) or the FPM (feet per minute).

We at Air Shammy motorcycle dryer will not publish any specifications of our dryer that is not true. We will not state any specifications that we cannot back up with test data or calculations. We think you are smarter than to believe some of the things you read.

If you are confused or just need more information, please give us a call at (800) 367-0641 or drop us an E-mail We will be happy to talk to you or write you back.

By the way, that biker that called us – He bought an Air Shammy motorcycle dryer!