How do we measure torque and what effect does it have on acceleration?

Engine torque - how to measure? — (photo: Unsplash)

Artur Owczarek

Brand Product Manager Moje AutoHe has been involved in the automotive industry for years. He is passionate about cars and detailing. On his blog, he shares his knowledge and experience, offering tips on how to effectively care for your car and extend its life.

To describe the engine's performance, we provide its power and torque. These are the two most important parameters responsible for the characteristics of the vehicle. Both contribute to its acceleration. Despite the increasing awareness of the impact of both factors on the operation of a car, there are still debates about which of them is more important. In the case of a car drive, we most often provide the value of acceleration and force. Less importance is attached to torque. This is often due to lack of knowledge of what it actually is. Not everyone knows how to measure it properly and that it is worth controlling this value.

What is torque?

Not only does it need to be explained what it is torque, but also how it differs from engine power. Torque is the power of the internal combustion engine. The higher this value, the more easily we can overcome any resistance that appears while moving along the road. Engine power we, in turn, determine the work performed in a specific time. Power arises from engine torque and its rotational speed.

An interesting comparison to explain the difference between these values is to use the propellers of a wind turbine and a small office fan. Higher torque characterized by windmill power plant. You have to use a lot of force to stop it, even though it rotates slower. The small office fan is high in power but low in power torque. It can be stopped much easier and faster.

It is similar in the case of car engines. Tall torque i little engine power they make the vehicle pull heavier loads better, but they don't respond best to acceleration commands. Cars with low torque and big engine power they will accelerate better, but will lose thrust more easily.

The crankshaft is responsible for the rotational movement. It must overcome resistance and load for the drive unit to work properly. Various mechanisms and car elements put up resistance. For proper acceleration engine torque must be sufficiently higher than the resistance of the vehicle.

Torque and acceleration

Torque is the force that can be obtained from the drive unit. Responsible for, among others: for towing capacity, so it is thanks to it that it is possible, for example, to tow a car. Achieving the right one torque is necessary for the vehicle to accelerate under heavy loads. It means that torque and acceleration are proportional to each other. The car can therefore be tall engine torque at high engine speeds and thus accelerate easily. Following this line of thought, it is worth mentioning again: engine power. It determines the maximum speed of the vehicle. However, it will only be achieved when the drive system gear ratios are set correctly.

How to measure engine torque?

You already know that engine torque determines acceleration. Therefore, it is worth knowing what its value is. Each drive unit is characterized by individual torque and power curves. Their values are set for the entire engine speed range. On this basis, a chart is created that describes a specific drive unit. To calculate engine torque, please use the following formula:

POWER (HP) = torque rpm (Nm) x rpm (RPM) / 7023,5

If you want to read the result correctly, use ready-made charts prepared for your car. Engine torque also works on measuring devices.

(My Car infographic)

Torque and power – what is more important?

It cannot be clearly stated that engine torque is more important than power or vice versa. In fact, the shape of the torque curve is crucial. The car will drive faster if the graph looks "nicer". We will obtain it with higher torque and with its availability in a wider range of rotational speeds. There is more power when the engine revs higher and there is more torque.

Many drivers wonder why diesel, which has more power and torque, performs worse than many gasoline engines. It is unable to achieve high revolutions due to its design limitations. Higher torque and thus the power in diesel engines was achieved by adding a turbocharger to them. However, this did not allow for higher torque. Diesel is a powerful engine, but only for a short time.

The ideal engine is one whose torque curve runs flat and high. This was achieved in the case of an F1 car, which was equipped with a light engine with a small piston stroke. The supercharger provides high pressure over a wide rev range. However, this type of engine would not work well in passenger cars and trucks.

Torque and the type of engine

Engine torque has a major impact on the driving experience, which is different between petrol and diesel engines. With the same power, petrol and diesel cars will accelerate differently. Torque in a diesel engine it is high, but within a narrow range of rotational speeds. This allows us to feel greater acceleration, but unfortunately for a short time. This means you need to shift to a higher gear. Lower torque is in gasoline engines. It is also available at higher rpm. The engine accelerates less rapidly, but we can accelerate longer in individual gears.

(infographic. My Car)

Od engine torque depends on the acceleration of the vehicle. However, it cannot be equated with engine power. However, you need to be aware of the relationship between them. You can also measure torque, using the given formula or verify its value on measuring devices.