What is horsepower and torque and how do they relate to a car being fast or a truck having a towing capacity?
In: Engineering
Torque is twisting power, always, by that I mean the ability to do some level of “work”. Having more torque than is necessary for the application is wasteful. To get horespower, you multiply torque times engine speed (set by manufacturer) divided by 5252. That describes the speed with which you can get some amount of work (as defined by torque) done.
A car with 100 HP and 100 foot pounds of torque will be slower than a 110 HP car with 100 foot pounds of torque. However, you have to consider the weight of a vehicle and other load factors, like whether you are going up hill. So if you need to tow something and you really only need to have highway speeds then a diesel, which has far more torque than horsepower is a good idea. If you have a race car then you will invert that, favoring horsepower to torque. There are a few notable race cars (like the Audi R18) that run on diesel and they make up for the lower HP by making the car lighter, more aerodynamic, stable, and it controls how the torque gets put down so as not to shred out your tires.
In many ways, we don’t really care about horsepower, I can simply spin the motor faster (which is why redlines on Porsche’s and the GT 350R are far higher than a non-racing engine) to get more speed to the ground. Increasing torque is a lot harder, I need to find a way to get more air molecules and fuel into the cylinder, so I have to stroke it, bore it, add valves, add cylinders, or add forced induction. Forced induction is just any turbine that will compress a bunch of air and jam them into the cylinders to get more explosive power. That turbine comes in two general forms, a turbocharger which is spun by the exhaust gases or a supercharger which is spun by a belt connected to the motor. Both products are essentially just turbines, the difference is what feeds the turbine energy to compress the air.
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