If you’re old enough to drive, chances are you understand the basics of how a car engine works. Gas and fuel are mixed together into a chamber, and that fuel mixture is ignited in a small explosion. The force of that explosion pushes down a piston and creates the energy that’s used to move the car. But where do all those things like horsepower and torque come in?
Generally speaking, horsepower is a measure of the ability to do work. The term originated way back when folks wanted to compare steam engines against draft horses. Hence, an engine began to be rated according to how many horses it could do the work of. This same measurement of power began to apply to more than just steam engines, eventually being used in everything from piston engines to electric motors.
However, it’s important to note that although the term horsepower is used in a variety of different applications, it means something slightly different in each one. Horsepower is also a bit of a marketing dodge, because horsepower may not actually translate into how much work an engine can do under normal conditions, but rather refer to only optimal conditions. In this case, it’s buyer beware – be sure to evaluate the car on all of its merits, not just the purported horsepower rating.
The concept of torque has to do with putting that horsepower to use. When you turn a screw driver, for example, you’re applying torque, on in this case, using power (your strength) to rotate a fixed shaft (the screwdriver).
In a car, think of horsepower as providing the arm strength and torque as the application of that power to turn the wheels. This is a considerably over-simplified explanation, but in the confusing world of auto mechanics, it will give you at least a working knowledge.
When a car has higher horsepower, it has the capability of delivering more power. Whether or not that capability is realized is, as we mentioned, another story. A car with high torque will tend to accelerate quickly – that high torque can get those wheels turning quickly, so you can accelerate more quickly. Again, this isn’t an absolute and depends on several other things, like gear ratios, the weight of your car and its aerodynamics.
One of the key things to remember is that horsepower and torque work together with other aspects of the car’s engine and engineering to affect the car’s performance. Higher torque generally means quicker acceleration. Lower torque combined with higher horsepower will lead to a higher revving engine and more power in the upper range of each gear. Higher torque with lower horsepower, on the other hand, leads to more power in the lower range of each gear.
The best car for you will have a mix of horsepower and torque that works together to accomplish what the car needs to do. Obviously, a minivan is going to need a different blend of horsepower and torque than a sports car to do its job well. If you’re feeling overwhelmed by this explanation of these two concepts, don’t worry – if you take the time to test drive a car you’re interested, you’ll know right away whether or not it has the power you need.
