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A chassis dynamometer.. A dynamometer or "dyno" is a device for simultaneously measuring the torque and rotational speed of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by the dynamometer itself as kW or bhp.
Engine power is the power that an engine can develop. It can be expressed in power units, most commonly kilowatt, metric horsepower (often abbreviated PS), 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 ...
Tax or fiscal horsepower is a non-linear rating of a motor vehicle for tax purposes. [19] Tax horsepower ratings were originally more or less directly related to the size of the engine; but as of 2000, many countries changed over to systems based on CO 2 emissions, so are not directly comparable to older ratings.
Speed has dropped out of the equation, and the only variables are the torque and displacement volume. Since the range of maximum brake mean effective pressures for good engine designs is well established, we now have a displacement-independent measure of the torque-producing capacity of an engine design – a specific torque of sorts.
In typical combustion engines found in vehicles, the torque is low at idling speed, reaches a maximal value between 1,500 and 6,500 RPM, and then falls more or less sharply toward the redline. Below the RPM of maximal torque, the intake air velocity and thus mixing of air and fuel is not ideal.
With a governor set to 8% accuracy, the rated power is 21.33 kW (29 bhp; 29 PS) at 3000 min −1, the highest torque is 69.63 N⋅m (51 lbf⋅ft) at 2000 min −1. [4] For other applications, the power and torque output may vary, e.g. On the Beetle produced 41 PS (40 bhp; 30 kW) at 3900 rpm and 88 N⋅m (65 lbf⋅ft) of torque at 2400 rpm.
is the engine speed in radians per second (rad/s) τ {\displaystyle \tau } is the engine torque in newton metres (N⋅m) The above values of r , ω {\displaystyle \omega } , and τ {\displaystyle \tau } may be readily measured by instrumentation with an engine mounted in a test stand and a load applied to the running engine.
The efficiency of internal combustion engines depends on several factors, the most important of which is the expansion ratio. For any heat engine the work which can be extracted from it is proportional to the difference between the starting pressure and the ending pressure during the expansion phase. Hence, increasing the starting pressure is ...