If you’re a car enthusiast or even just a daily driver, you’ve heard the terms horsepower, torque and top speed. You probably know that they all refer to the power of the car, but it might be hard to give each term a solid definition. How is horsepower measured? What might contribute to more or less torque in the vehicle? All these are important questions if you’re looking at how to best optimise your ride for your style of driving. This article will give a bit of an explanation on the differences and importance of all three.
Horsepower: Instant Power Output
Essentially, horsepower refers to how fast the output of the engine occurs or how quickly the engine does its work. The term was coined in the 18th century by a steam engine manufacturer who wanted to demonstrate the power of these machines by comparing them with horses, a relatable comparison at the time. Little did he know that this would be the benchmark for the future of engine power measurements moving forward.
Horsepower was first calculated by how many pounds a strong horse could pull per minute. He first calculated that a horse could pull 180 pounds of force over 181 feet per minute. This translates to about 33,000 foot-pounds per minute, which equals one horsepower. If you convert that to metric numbers (for us Australians), it equates to about 81 kilograms of force pulled over a distance of 55 meters per minute.
Torque: The Force Behind Acceleration
Torque refers to the rotational force that is produced and is the measurement of the amount of twist that engines have on their wheels. It is what gets your vehicle moving from rest; it helps to haul and pull larger loads or push forward large vehicles. The way torque is measured is typically by pounds-feet or newton-meters. This was standardised in the 19th century as a means of formal measurement.
The torque can be calculated by multiplying the force by the distance past its pivot point, so essentially, it’s how hard you push or pull and how far from the pivot you apply that force. For example, a longer wrench will make turning something much easier as its length provides additional torque. So if you apply 10 pounds of force on a 2-foot wrench, it results in about 20 foot-pounds of torque.