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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.
The mean piston speed is the average speed of the piston in a reciprocating engine. It is a function of stroke and RPM. There is a factor of 2 in the equation to account for one stroke to occur in 1/2 of a crank revolution (or alternatively: two strokes per one crank revolution) and a '60' to convert seconds from minutes in the RPM term.
If we know the crankshaft speed, we can also determine the engine's power output from the MEP figure: = In our example, the engine puts out 159 N·m of torque at 3600 min −1 (=60 s −1 ): i = 0.5 {\displaystyle i=0.5}
This formula may also be used to calculate the power of a jet engine, using the speed of the jet and the thrust required to maintain that speed. Example: how much power is generated with a thrust of 4000 pounds at 400 miles per hour? {} = =
The engine control unit can then calculate engine speed (angular velocity). Speed sensors used in automobile transmissions are used to measure the rotational speed (angular velocity) of shafts within the transmission.
The useful power of an engine with shaft power output can be calculated using a dynamometer to measure torque and rotational speed, with maximum power reached when torque multiplied by rotational speed is a maximum. For jet engines the useful power is equal to the flight speed of the aircraft multiplied by the force, known as net thrust ...
Characteristic velocity or , or C-star is a measure of the combustion performance of a rocket engine independent of nozzle performance, and is used to compare different propellants and propulsion systems. c* should not be confused with c, which is the effective exhaust velocity related to the specific impulse by: =. Specific impulse and ...
For speed the corrected value is corr = / Example: [17] An engine is running at 100% speed and 107 lb of air is entering the compressor every second, and the day conditions are 14.5 psia and 30 deg F (490 deg R).