The Truth About Torque: What Is It & Why Does It Matter?
Horsepower & torque are often referred to when purchasing a car but what are the differences and why do they matter?
Aug 04, 2015
Horsepower and torque. These are the words you will repeatedly see together when researching specifications of a car model. Torque is the figure measured in pounds per foot (lb – ft.) which lets you gauge how much power you’re getting, and is often bragged about by car enthusiasts.
But what is torque? How does it differ from horsepower and why is it important? If you aren’t 100% sure then you’re definitely not alone. These are the big questions that the automotive industry seems to assume we know the answers to, so never fully explain. Here we will dispel the mystery surrounding torque and give you those answers in simple terms.
Definition of torque
Do a quick Google of ‘torque’ and you will be faced with this mechanical definition:
“a force that tends to cause rotation.
‘the three-litre engine has lots of torque’”
Not very clear is it? However if you dig further into a few online articles and get through the wordy explanations, you will find that torque basically means how much power it takes for the car to reach a certain speed. So the more torque your car has, the greater the acceleration.
Torque’s role in a car engine
Torque is a crucial part of generating power from a car’s engine, as it represents the load an engine can handle to generate a certain amount of power to rotate the engine on its axis. The force is measured in pounds (lb) per foot (ft) of rotation around one point. Multiply this torque force (in lb-ft.) by the axis’s rotational speed per minute (RPM) and you get the engine’s power output. This is what dictates how effectively the car can accelerate at different speeds and is important for high-performance cars.
This graph demonstrates how torque and horsepower relate to one another, with torque shown vertically and RPM horizontally. The torque force in the graph peaks at just 2,500 RPM, meaning the vehicle has ‘low-end torque’. This is common in high performance cars as the Nissan NISMO range and the all-new Ford Focus RS which can accelerate very quickly from low speeds.
- The all-new Ford Focus RS has 325 lb-ft of torque between 2000-4,500rpm (low-end torque). This means that the engine can move 347lb of force within one foot of engine rotation and accelerates quickly from low speed.
The graph demonstrates the torque curve next to horsepower for a low-end torque car.
If you want to look at torque the opposite way around, trucks carrying heavy loads require ‘high-end torque’ where torque force peaks at a higher RPM. This means the truck would be slower to accelerate, but the level of torque would allow it to handle the extra weight as RPM increased.
Benefits of torque
More relaxed driving experience - If your car has low-end torque, it generally means that you have access to more engine power in lower gears. As a result, you won’t have to down-shift the gears so often when accelerating from low speeds, and the drive will feel more relaxed.
Easier to carry heavy loads - As mentioned earlier, torque is beneficial if you own a truck carrying heavy cargo. Having high torque force as the engine rotation (RPM) increases makes transporting heavy loads far easier and more efficient.
Easier for driving up steep inclines - Having extra torque is also what creates enough power to get a vehicle going from, particularly when moving up steep inclines. So torque can be useful when driving off-road and in extreme conditions.
Torque vectoring – Torque vectoring is a fairly new technology which provides the car’s differential with the ability to distribute certain levels of torque power in each wheel. This technology is popular in all-wheel drive cars, where the torque distribution to all 4 wheels improves grip and handling. In front-wheel drive cars, torque vectoring effectively balances the car. For example if the road is slippy, torque can be reduced in one wheel and increased in the opposite one to act as a brake and counteract the slip.
Torque Tip: If you own a car with a high performance engine, you can add more torque through revs. If the gearbox and differential reduce crank RPM to wheel RPM by 9 times, you therefore get 9 times the torque in the wheels. So the right use of gears can convert low engine torque into high torque, but at the cost of speed (RPM).