To be honestly, we are sometimes confused by all the various phrases thrown around as it relates to Horse Power….so while we were bouncing around the internet we found this information which helped clear things up a bit. Someone says, “yeah, its fast, it’s got 160 brake horse power”–or how about “it’s got 140 horsepower on the back wheel”. Or how about “I’ve got 23kw” of power in this rocket”.
Funny, “brake” horsepower has nothing to do with braking (a blonde joke in here somewhere?). Often those speaking the mighty hp talk are not clear themselves. Is it the engine measurement or the actual output to the wheel considering how the gearbox, final drive and all those assisting parts cause loss of power through the whole process. The actual horsepower delivered to the driving wheel is less in measure than the raw output of the engine and so forth. Horsepower invented/discovered by James Watt, the same person whose been immortalized by the definition of Watt as a unit of power-i.e. light bulb. The Scottish engineer created this metric measure originally aiming to prove and substantiate the power of the steam engine he invented. Therefore, we ended up with a few types of measurements for hp.
bhp:Brake horsepower: net, bottom line crankshaft horsepower — the power delivered directly to and measured at the engine’s crankshaft, its minus (net) frictional losses in the transmission — gears, bearings, oil drag, wind, and so forth.

ehp or thp:Effective horsepower is the power converted to useful work. In the case of a motorcycle, it’s the power that’s been turned into forward motion on a chassis dynamometer. In its cleanest form, it’s also called “True HP” – wheel power

nhp:nominal horsepower from the size of the engine and the piston speed and is only accurate at a pressure of 7 psi

ihp:Indicated horsepower or gross horsepower (academic capability of the engine) minus frictional losses within the engine (bearings drag, rod and crankshaft windage losses, oil film drag, etc

SAE:an American standard rating measured using a blueprinted test engine running on a stand without accessories, mufflers, or emissions control devices.

As a motorcyclist we are most interested in the first two above—bhp and ehp “effective horsepower” which is in simple terms specified as wheel horsepower. In order to measure horsepower you need to hook your motorcycle engine up to a dynamometer that places a load on the engine and measures the amount of power that the engine can produce against the load. A service easily found at the track or at dealerships.
In addition, just so you know thp is generally about 10% to 20% lower than the engine’s power “bhp” ratings because of the loss experienced through the drive train, and especially the tyres. So now you know and won’t feel out of the loop when amidst one of these most common of topics for boosting and bragging in motorcycle chitchat.

Horsepower and lots of it is one of those status things amidst motorcyclists. The more you got, the better rider you’re suppose to be—apparently. A total myth. Many riders have enough, and usually it’s far more than the skills ability. There are many motorcycle riders, and competitors with under a 100 thp who’ll lap a 140thp rider any time, any place. Its ok to have it, its another being able to use it—kinda like owning a pair of high priced cowboy boots, but not being able to fit into them.
Some additional dense stuff:
Bhp defined: Horsepower is a measure of work (energy) done over time and yes it was calculated using the work of a horse. 1hp/one horsepower is 33,000 lb.-ft/minute.
Use this popular analogy– if you lifted 33,000 pounds, one foot over a period of one minute, you would be working at the rate of one horsepower—and have spent one horsepower-minute of energy. 1 (mechanical) horsepower unit is equivalent to 746 watts
So if you took this 1-horsepower horse and put it on a treadmill, it could operate a generator producing a continuous 746 watts.
One mechanical horsepower equals 745.699 watts or .746 kW (kilowatts) of electrical horsepower–and if you really want to talk hp you could refer to the 0.0268 horsepower light bulb in your lamp as opposed to the using the mundane 20-watt measurement.

Hey, thanks for coming back! Great to see there are a few of you out there that have taste and style! Seriously, thanks for visiting. If you know of stories you think people would be interested in, shoot us a line C'ya!

This entry was posted on Monday, April 23rd, 2007 at 8:05 am and is filed under General Motorcycle Industry News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.