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HP vs. torque: What is the difference between power and torque?

Terms such as torque and power reflect important parameters of engines. But the meaning is not always clear, and often the indications cause confusion. What does Newton metre or Nm mean, and what in turn are the horsepower of an engine? In our guide to power and torque, we explain the difference and provide answers to all the important questions.

What does PS mean?

The power of cars is often expressed in horsepower. The abbreviation PS stands for horsepower. The unit of measurement PS is now considered obsolete, but is still frequently used in common parlance. In official documents such as the vehicle registration certificate, however, the power of a car is stated in kilowatts kW.

Today, the specification of horsepower is mostly only found in the car quartet. But drivers also often state how much horsepower their car has when asked about its performance. Fortunately, power in hp or kW is relatively easy to convert. A power of 1 kW corresponds to 1.36 hp, whereas 1 hp represents a power of 0.735 kW.

What are kW?

The abbreviation kW stands for kilowatt and, like horsepower, indicates the maximum power of the engine in cars. The basic unit is again watt, 1000 watts are one kilowatt. The power rating indicates the amount of energy that can be converted in a specified unit of time. Today, it is customary to always quote the engine power of a vehicle in this unit.

An engine can achieve high power either through high torque or at high speeds. The maximum power is usually only available in the upper speed range. The power of cars with an electric motor is specified exclusively in kilowatts. This should not be confused with the charging power of the electric car.

What is the torque?

Torque is a classical quantity in physics and mechanics. The usual unit of measurement for torque is called the Newton metre and is designated by the abbreviation Nm. This physical quantity indicates the rotational effect with which a certain force acts on the pivot point of a body.

In a car, torque is defined as a force that acts as a rotation on the drive shaft of the engine. Here, the driver is most likely to perceive high torque as a strong pull-through. This is particularly noticeable in electric cars, where the maximum torque is available from the start and at any speed.

What is the relationship of power and torque?

In the internal combustion engine in a car, the variables torque and power are directly related. A certain power can be generated from different constellations of torque and speed. Both values are therefore dependent on the speed.

Power and torque are defined differently. While high power is usually only available at high engine speeds, high torque can already be available at relatively low engine speeds. Maximum torque is also available at lower engine speeds.

Torque or power – which is of greater importance?

Car manufacturers always state the values of power and torque for a vehicle. The question arises as to which value is more important. In practice, this is mostly torque, even though cars are still rated according to their power such as hp and kW.

In practice, an engine with high torque allows good acceleration, which is often important in road traffic. For the driver, the engine with a lot of torque opens up a good pull from the rev range. A car with a lot of power, on the other hand, is more likely to allow a high top speed to be reached.

Difference between horsepower and torque – a practical example

The difference between the power in hp and the torque in Nm often becomes apparent in practice. For example, a tractor for agriculture may have a rather low effective power in comparison. However, the engine can generate enormous power from the few hp, as it has been designed for high torque. Thus, the tractor can already pull a heavy trailer from a standing start.

The relationship between horsepower and Nm can be completely different for a sports car, because other factors apply here. This type of vehicle is designed for maximum performance on the road and to reach high speeds. While the sports car can go particularly fast with its horsepower in the triple-digit range, there is no such high torque available, especially when starting off.

How much horsepower and torque – Effects on maintenance and repair

Properties such as power and torque can sometimes become interesting factors in the maintenance and repair of vehicles. This is because the highly developed engines installed in modern cars should also generate high torque at as many revolutions per minute as possible.

Such engines often have a turbocharger and a smaller displacement than an engine without a turbo. This in turn has an influence on the engine design. For this reason, the maintenance of such an engine can also be more complicated.

What impact do these circumstances have on the purchase of spare parts

What power and torque a vehicle has can even make a difference when buying spare parts. This is due, among other things, to the design of today’s engines. Among other characteristics, these should show as balanced a torque as possible over a wide speed range and also at low speeds.

The engines with turbochargers that are frequently used for this purpose are more complex in terms of their design. For example, turbocharged engines have many additional parts, of which the turbocharger is only one. Therefore, more and different spare parts are needed if an engine is defective.

There are also differences in high-horsepower cars with a lot of power and, in comparison, vehicles with a lot of torque. Components that are subjected to high torque, such as a shaft, can break down more quickly than others due to the load.

Cars with a lot of horsepower, on the other hand, are often driven much more sportily than normal everyday vehicles with significantly less power. This can result in higher wear and tear on certain components. In addition, the parts for vehicles with high power are sometimes more expensive.

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