How to choose between power and torque

choose between power and torque

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“How much horsepower does yours have?” – not only in the case of the car quartet, this is a frequently asked question. For many, the performance of a car is still very important. Rightly so? When buying a car, many consumers pay attention to power vs torque. However, if you look at the performance-related technical data of a vehicle, you can’t avoid another physical quantity: torque. But what is actually more important? Our guide explains how to choose between power and torque.

This cannot be answered in general terms. Vehicle expert Christian Heinz explains that the significance depends on the specific situation: “Basically, the power and torque of an engine are relative key figures, which only allow further conclusions to be drawn in conjunction with the engine speed.”

In the physical sense, power is the energy that can be converted in a certain period of time. For vehicles, the rated power is usually expressed in kilowatts (kW), or horsepower (PS).

Advertising is usually done with power

So how do you choose between power and torque? The rated power printed in catalogues and documents describes the maximum possible power that an internal combustion engine can usually deliver only at relatively high speeds at a short below the maximum speed. Since in everyday life driving is usually at significantly lower speeds, less power is usually available.

The torque indicates the force that acts on the drive shaft during rotation. It is therefore specified in newton meters (Nm). The maximum torque for internal combustion engines is already at much lower speeds than the maximum power.

The higher the torque and the lower the required speed, the more powerful the vehicle can accelerate out of the speed cellar. “Cars with turbo diesel engines in particular are known for high torque at low speeds. As a result, they are also particularly well suited as towing vehicles for trailers and facilitate shift-lazy driving,” explains Heinz.

Modern engines balance a lot

In comparison, gasoline engines without charging have a much lower torque at low speeds. They require higher speeds if the driver wants to accelerate powerfully, heinz said. “Modern petrol engines with turbo charged or compressor charging are increasingly relativizing this disadvantage, even offering relatively high torque at low speeds.”

And what role does nominal power play? “It is the indicator of the available force of the engine when it is fully required.” If you want to know how fast a car reaches a certain speed at maximum acceleration – from 0 to 100 km/h, a comparison of the performance usually provides the better indications than a comparison of torque.

“In such a manoeuvre, high torque at low speeds hardly plays a role, because the motor is permanently in the top speed range.”

The power is usually not fully utilized

However, the consumption and exhaust emissions of the engines are becoming increasingly important, especially in the course of mobility. “Manufacturers today tend to value a wide speed range in which torque is as consistently high as possible than that the motors are developed with maximum power in mind,” says the expert.

In everyday life, vehicles are in demand, which on the one hand have a high elastic range and can be driven through at low speeds, and on the other hand, due to a high torque at low speeds, a very effective and fuel-saving driving style.

High performance parameters are more important for speeding up and achieving maximum speed. This still plays an important role at the regular table, for example. In practice, however, the power reserves mostly remain unused.

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