Horsepower can be measured in several ways. The most common way is to measure it directly using a device called a dynamometer, or dyno for short. Dynamometers fall into two major categories: engine dynos and chassis dynos. An engine dyno, as the name implies, is connected directly to an engine, with the engine not installed in the car. A chassis dyno, on the other hand, is connected to the drive wheels of a car, and measures the power actually put to the pavement. Since transmissions and other parts have friction that will reduce the power, chassis dyno measurements are lower than engine dyno measurements. The horsepower rating a car has from the factory is always measured on an engine dyno. The measurement from a chassis dyno is ...

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