How is horsepower measured?
The power of a car engine is measured by means of metal rolls when the car’s driving wheels are placed on the metal rolls. When the wheels rotate, the rolls rotate at the same speed. The rotation is recorded by an instrument known as a dynamometer, which registers the wheels’ torque and rotations per minute.
The data is used by a computer to calculate the HP of the engine based on a formula. 1 HP is the equivalent of about 736 watts – the physical force needed to lift a mass of 75 kg 1 m vertically above the ground in one second. In spite of the name, 1 HP is not the equivalent of the power of one horse. The animal can produce 2.5-10 HP.
Two rotating metal rolls measure the HP of a car engine.