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Horsepower (hp) is a unit of ... rotational speed N is in rpm, the resulting power in horsepower is {} = {} ... This formula may also be used to calculate the power ...
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.
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.
A typical turbocharged V8 diesel engine might have an engine power of 250 kW (340 hp) and a mass of 380 kg (840 lb), [1] giving it a power-to-weight ratio of 0.65 kW/kg (0.40 hp/lb). Examples of high power-to-weight ratios can often be found in turbines.
The following laws are derived from the two coefficient equations by setting the coefficient for one operating condition (e.g. Q 1, n 1, D 1) equal to the coefficient for a different operating condition (e.g. Q 2, n 2, D 2). Law 1. With impeller diameter (D) held constant: Law 1a. Flow is proportional to shaft speed: [2]
where rotational speed is in revolutions per minute (rpm, rev/min). Some people (e.g., American automotive engineers) use horsepower (mechanical) for power, foot-pounds (lbf⋅ft) for torque and rpm for rotational speed. This results in the formula changing to:
An 'inertia' dynamometer provides a fixed inertial mass load, calculates the power required to accelerate that fixed and known mass, and uses a computer to record RPM and acceleration rate to calculate torque. The engine is generally tested from somewhat above idle to its maximum RPM and the output is measured and plotted on a graph.
Its SI unit is the reciprocal seconds (s −1); other common units of measurement include the hertz (Hz), cycles per second (cps), and revolutions per minute (rpm). [ 1 ] [ a ] [ b ] Rotational frequency can be obtained dividing angular frequency , ω, by a full turn (2 π radians ): ν =ω/(2π rad).