What is the relationship between torque and power?
2 Answers
Power refers to the amount of energy output per second, or the force multiplied by the distance in the direction of the force; torque is the product of the output force and the perpendicular distance from the force. Torque affects acceleration, while power affects top speed. Engine power = torque * RPM. Below is an introduction to power and torque: 1. Power refers to the work done by an object per unit of time. It is a physical quantity that indicates how fast an object performs work. The higher the power, the higher the RPM, and the higher the maximum speed of the car. Maximum power is commonly used to describe a car's dynamic performance and is usually expressed in metric horsepower (PS) or kilowatts (kW). 2. Torque refers to the average moment output from the crankshaft when the engine is running. It is an important parameter of engine performance, reflecting the car's load capacity within a certain range. Under fixed power conditions, it has an inverse relationship with engine RPM—the faster the RPM, the smaller the torque, and vice versa. The greater the torque, the more "force" the engine outputs, and the faster the crankshaft RPM changes, improving the car's climbing ability and acceleration.
After decades of driving, I've come to deeply understand the relationship between torque and horsepower as the dual personalities of an engine. Torque is that raw strength at low speeds, instantly getting the wheels turning—it's what you rely on when climbing steep hills or hauling heavy loads, determining whether the car stumbles or moves steadily. Horsepower, on the other hand, is like endurance at high speeds, delivering power at high RPMs to push the car to its limit. Roughly speaking in mathematical terms, horsepower is approximately torque multiplied by engine speed divided by 5252 (but don't memorize the number), meaning cars with high torque at low RPMs are more agile, while horsepower dominates at high RPMs. When driving on mountain roads, the high torque of a diesel car helps me climb effortlessly; on highways, the high horsepower of a gasoline car saves me fuel and hassle. When choosing a car, looking at the engine curve can tell you whether it's suited for city driving or long trips.
