Search results
Results from the WOW.Com Content Network
Engine power is the power that an engine can put out. It can be expressed in power units, most commonly kilowatt, pferdestärke (metric horsepower), or horsepower.In terms of internal combustion engines, the engine power usually describes the rated power, which is a power output that the engine can maintain over a long period of time according to a certain testing method, for example ISO 1585.
Two common definitions used today are the imperial horsepower as in "hp" or "bhp" which is about 745.7 watts, and the metric horsepower as in "cv" or "PS" which is approximately 735.5 watts. The electric horsepower "hpE" is exactly 746 watts, while the boiler horsepower is 9809.5 or 9811 watts, depending on the exact year.
It is an administrative unit originally calculated partly from the power of the engine and used to calculate the amount of tax that may be due at the time of registration. The Citroën 2CV (two tax horsepower) was the car that kept such a name for the longest time. Its use in France dates from 1 January 1913.
For example, an unloaded motor of = 5,700 rpm/V supplied with 11.1 V will run at a nominal speed of 63,270 rpm (= 5,700 rpm/V × 11.1 V). The motor may not reach this theoretical speed because there are non-linear mechanical losses.
If Imperial units are used, and if torque is in pounds-force feet and rotational speed in revolutions per minute, the above equation gives power in foot pounds-force per minute. The horsepower form of the equation is then derived by applying the conversion factor 33,000 ft⋅lbf/min per horsepower:
Main page; Contents; Current events; Random article; About Wikipedia; Contact us
This template employs intricate features of template syntax. You are encouraged to familiarise yourself with its setup and parser functions before editing the template. If your edit causes unexpected problems, please undo it quickly, as this template may appear on a large number of pages.
To calculate the actual efficiency of an engine requires the energy density of the fuel being used. Different fuels have different energy densities defined by the fuel's heating value. The lower heating value (LHV) is used for internal-combustion-engine-efficiency calculations because the heat at temperatures below 150 °C (300 °F) cannot be ...