Two automotive performance terms reign supreme: torque and horsepower. While closely linked, these metrics actually describe different roles within the engine – torque measures an engine’s raw strength and ability to do work, while horsepower quantifies how quickly your car gets that work done.
Whether this part is on an Aston Martin or a Maserati you can be sure torque plays a pivotal role in its success. But what does torque mean in cars, exactly? On this page, we’ll explain exactly what torque means in cars (and in scientific terms), how it differs from horsepower, and its impact on engine performance.
Now, let’s find out how torque drives our cars forward…
What is torque?
In physics, torque is the twisting force applied at a pivot point with the help of a lever arm. The formula for torque, also known as the law of the lever, is:
torque = force (N) x lever arm (m)
Torque is measured in newton-metres (Nm) or pound-feet (lb-ft), where newtons (or pounds) represent the force applied, and metres (or feet) represent the length of the lever arm.
To figure out torque, you simply multiply the force you’re putting on the lever by the length of the lever. So, with a longer lever, you can generate more torque.
Torque’s also known as rotational force. This means that torque makes an object turn, like when you tighten a wheel-nut or bottle cap. In cars, torque shows the force acting on a car’s crankshaft when it turns, while Force (N) moves objects in a straight line.
Let’s say you’re tightening a wheel-nut with a wrench or lever. If you apply 2 pounds of force with a 1-foot long lever, you’re using 2 pound-feet (lb-ft) of torque on the wheel-nut. However, if you apply the same force with a 10-foot long lever, you’re using 20 lb-ft of torque on the wheel-nut.
How torque works in a vehicle
In simple terms, torque measures how much work your car can do. More torque means the engine can generate more power, so if your engine has high torque, your car can speed up faster when starting. Torque is also crucial when your car is doing tough jobs, like carrying heavy cargo or going up steep hills.
For the driver, having high torque means that when you press the gas pedal, the engine responds quickly. This high torque gives you, the driver, a strong feeling of traction when starting or passing other cars.
So, having robust torque right from the start should give you more confidence to pass other cars, while providing a more enjoyable driving experience and efficient forward motion.
What is torque in cars in scientific terms? Well, torque is defined as the engine’s rotational strength, used to measure the engine’s working output. It shows how much force it takes to twist something, like when you tighten a nut or turn a door knob.
For engines, torque tells us how much twisting power is available at the crankshaft at different speeds or revs per minute (RPM) – in regular cars, you want a lot of torque early on at low speeds, while electric cars have high torque right away.
With all combustion engines, there’s always a brief moment of delay (though it’s usually small and depends on the engine’s design) before the torque fully kicks in – unlike in an electric car.
How size and weight affects torque
Back in the 1980s, torque wasn’t talked about much in car ads. That’s because the cars of that era were much lighter compared to today’s heavier models packed with advanced tech, comfort features, and safety equipment. As a result, they need more force, or torque, to set them in motion.
This is why bigger cars often come with diesel engines, as they provide more torque at lower revs compared to petrol engines. And as cars grow in size and weight, torque becomes even more important.
For example, a small city car can run smoothly with relatively low torque, but larger cars like vans or 4x4s – like the Bentley Bentayga – need a substantial amount of torque to get them going.
What is torque in different engine types?
Here’s how torque works differently in petrol and diesel engines, and electric cars…
Petrol engines
In petrol engines, a spark plug starts the fuel burning process. The piston in the cylinder moves down before the fuel fully ignites, which means the piston has already started moving down before the fuel ignites. This makes the petrol engine work slower and reduces its torque.
When designing regular oil engines, you want to deliver strong torque or twisting power even at low engine speeds, and this power should then be spread over a wide range of engine speeds.
Diesel engines
Diesel engines make more torque than petrol engines because they compress more air. Unlike oil engines, they don’t need a spark plug to start the fuel on fire – they rely on hot air. This is linked to torque because, when the engine compresses the air more, it works more efficiently. This is why diesel engines have more torque: they have higher compression ratios.
Electric cars
Unlike traditional engines that need gears to reach high speeds, electric motors can deliver their maximum power instantly. Electric cars also have a component called a reducer, which is similar to a transmission in conventional cars. The reducer helps efficiently transfer the motor’s power to the wheels.
Because the electric motor provides a lot of power, the reducer adjusts the speed to match different driving conditions, which means electric cars can optimise their performance and save energy by reducing the motor’s rotations per minute (RPM) while maintaining high torque.
The difference between horsepower and torque
Torque and horsepower are closely linked in an internal combustion engine. In fact, you can’t have one without the other. Torque measures an engine’s capacity for work, while horsepower gauges how fast a car can complete that work, which directly relates to how fast the crankshaft turns.
The formula to calculate horsepower is:
Horsepower (HP) = Torque x RPM ÷ 5252
This means that when you compare two engines with varying torque levels, the engine with higher torque will always generate more horsepower at any specific engine speed.
Yet there are plenty of high-torque engines that aren’t designed for very high revolutions per minute (RPM), such as robust diesel engines. This can lead to some sacrifices in terms of overall power output.
On the flipside, a high-revving petrol-powered sports car may have a lower torque rating, but its ability to deliver immense power at high engine speeds allows it to achieve impressive speeds.
This is why, in everyday driving scenarios, the strong and adaptable performance of a high-torque engine is often more satisfying. Torque becomes crucial when you need a car or van for towing large trailers or transporting heavy loads.
If excessive torque has damaged your vehicle – be it the crankshaft, transmission, or drive axles – Scuderia Car Parts has you covered.
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