How is the horsepower of a truck calculated?

[StAlexis]

Horsepower equals torque multiplied by speed, symbolizing how much air-fuel mixture the engine can intake per unit time. Here is some related information about horsepower: 1. The origin of horsepower: "Horsepower" is a unit of power, commonly seen marked on diesel engines and steam turbines. Over 200 years ago, engineers manufactured the world's first batch of improved steam engines based on the design by British engineer James Watt. A brewery ordered one to replace horses in driving a water pump. The brewery owner wanted to determine whether the steam engine's productivity could match that of a horse. So he selected the strongest horse from his stable and had it work continuously for 8 hours. After conversion, it was concluded that a horse could lift 75 kilograms of water by 1 meter per second, i.e., 1 horsepower = 75 kilogram-force·meter/second. Since then, horsepower has been used as the power unit for mechanical engines and continues to be used today. 2. Metric horsepower: Metric horsepower, also known as PS (Pferdestärke), defines 1 metric horsepower as the work done to lift 75 kilogram-force·meter in 1 second. That is, 1 metric horsepower = 75 kilogram-force·meter/second = 735 watts.