Horsepower vs. Torque: A Simple Explanation
Everybody knows what horsepower is. Fewer people know what torque is. Both are very helpful when it comes to choosing a car and knowing how it will perform. Today, I’m going to simplify both so you can go wow your friends with all the knowledge you will need when you are out looking for your next car.
What is Horsepower?
This is a good place to start because more people are familiar with horsepower. It’s the number that’s flaunted in your face as your salesman explains your soon-to-be new car’s capabilities. Simply put, horsepower is an engine’s ability to do work. It’s how fast your engine is able to spin to create the movement of the car. It may seem obvious, but this why a 500 horsepower car is going to be faster than a 100 horsepower car. The higher horsepower number allows the car to go faster.
What is Torque?
Torque is a little different than power, but it’s no less relevant. It is the ability of the car to translate its horsepower to the pavement. In other words, torque is the car’s ability to use the horsepower that it has. Torque is measured in pounds feet or lbs./ft. So what does that mean for you? It means if you have two cars with 300 horsepower and one of them has 150 lbs./ft. of torque and the other has 400 lbs./ft. of torque, the car with more torque is probably going to feel much faster than the car with less torque, even if the two cars have the exact same amount of power and weight The car with more torque has a greater ability to use its power than the car with less.
Something else that we have to factor into the conversation is RPM. You know what that is too. Just about every car has a tachometer. A tachometer measures the Revolutions Per Minute that your car’s engine produces. It’s the gauge next to the speedometer that usually says something like, “X 100” or “X 10”.
When dealing with power and torque, there’s one more thing you will have to translate when learning to figure out exactly what you are looking at. Peak power and torque always work in tangent with a certain RPM. An example of this would be something like this: the 2018 Toyota Camry, with its standard 4-cylinder engine, produces 203 horsepower at 6600 RPM and 184 lbs./ft. of torque at 5000 RPM.
Now a Toyota Camry is a pretty basic car. It’s usable in just about every situation, but it’s not exactly known for being the fastest car. That’s OK because it’s not designed to be a fast car. Both the power and torque of the Camry are perfectly adequate for everyday driving, but let’s compare it to a car that’s known to be a bit sportier: The 2017 Mazda 6.
The Mazda 6 has a 2.5 liter, 4-cylinder engine, exactly the same size as the Camry, but the Mazda makes 185 horsepower at 5700 RPM and 184 lbs./ft. of torque at 3250 RPM. You’ll notice that both cars have almost identical torque numbers, but the Mazda 6 has almost 20 less horsepower. Despite that, the Mazda 6 has a 0-60 mile per hour time of 7.3 seconds while the Camry can only go from 0-60 in just a hair under 8 seconds. Why is that? The Mazda has less power… right?
Well that’s right, but there’s a very important number that’s different. While both cars have the same amount of torque, the Mazda 6 hits its peak torque number at 3250 RPM as opposed to the Camry at 5000 RPM. In addition to the way the car is tuned, the maximum amount of torque the Mazda 6 produces is reached sooner, and that helps the car accelerate quicker, even though the Mazda produces less horsepower. Not only that, but the Mazda’s peak horsepower is also reached at a lower RPM than the Camry. It also helps that the Mazda 6 is a big lighter.
If I’ve lost you in all of that, let me simplify it even more. 5000 RPM is a much higher limit than 3250 RPM. Especially in a Camry, whose main audience will be those who want to go somewhere comfortably and reliably, will almost never have to or want to push the car to 5000 RPM. Even under hard acceleration, the transmission would most likely change to the next gear by the time 4000 RPM is reached. In city driving, the car would almost certainly never go past 2500 RPM. Because of that, the Camry will almost never reach its peak torque number.
That being said, 3250 RPM is a much more attainable number. Even under modest acceleration, it’s entirely feasible that both the Mazda 6 and Camry would reach 3500 RPM under more aggressive acceleration. The Mazda 6 could easily hit peak torque under normal, everyday circumstances, making the car seem quicker and more responsive than the Camry, even with less horsepower.
–SWF
