Because power P = work W ÷ time t and work W = force F × distance s, P = F×s/t = F× speed v. Where v is the linear speed, in the engine, the linear speed v of the crankshaft = angular speed ω× radius r of the crankshaft, which is obtained by substituting into the above formula: power P = force F× radius r× angular speed ω; And force F × radius r= torque, so power P= torque× angular velocity ω is obtained. So the power of the engine can be calculated by torque and speed.
Extended data:
Torque (also known as torque) is a special torque in physics, which is equal to the product of force and arm of force, and the international unit is n m.
The maximum torque of the engine is related to the design of the intake system, fuel supply system and ignition system of the engine. At a certain speed, if the performance matching of these systems is optimal, the maximum torque can be achieved. In addition, the power, torque and speed of the engine are related, and the specific relationship is: power =K× torque × speed, where k is the conversion rate. When choosing an engine, we should also weigh how to use it reasonably and not waste existing functions. For example, air conditioning should be turned on in Beijing in winter and summer, and the engine power should not be too small when choosing; Just commuting on the city loop, there is no need to pick an engine with too much horsepower. Try to match the engine economically and reasonably.
Torque, like power, is one of the main indexes of automobile engine, which is reflected in automobile performance, including acceleration and climbing ability. Its accurate definition is the cross product (M) of potential vector (L) and force (F). In physics, it refers to the force of rotating object multiplied by the distance to the rotating shaft, which can indicate the output force of the engine (because the radius of the crankshaft in the engine is constant). Generally speaking, torque is an important criterion to measure the quality of an automobile engine, and the torque of an automobile is directly proportional to the power of the engine.
References:
Baidu encyclopedia-torque