Bhp vs. Torque
When reading about a car’s specifications, the most popular stat that often comes to mind is BHP or Brake Horsepower. This is a measure of how much power the car’s engine can actually make. Another, but less well known, stat is torque, which is a measure of how much turning force can be generated on the crankshaft. Torque is actually a physical quantity that can be measured, while BHP is a derived quantity that is the product of torque and RPM. All the talk about physics is a bit hard to relate to the real world and how it actually affects a vehicle’s performance, so let’s do some comparisons.
Torque is a more important value than BHP when you are considering acceleration. Take, for example, a forklift that has a lot of torque at low RPM. He can be quick to accelerate but he reaches his top speed pretty quickly since he’s pretty low. Although it may not be able to run very fast, it is capable of accelerating large loads without a problem. If you put the same amount of weight on your car, you may find that getting the vehicle in gear is a problem.
On the other hand, an F1 race car is the best example to illustrate how BHP is more closely related to speed than torque. An F1 race car generates a large amount of BHP when it is already moving at high speeds. Although it doesn’t produce a lot of torque, the huge RPM makes up for the high BHP output. If you’ve noticed, F1 race cars aren’t really that fast starting from the break and it can take a while before they can get up to full speed. That’s because they have very little torque at low rpm.
A streetcar is the perfect marriage between torque and BHP. It has enough torque to quickly rev up moderate loads while having enough BHP at high RPM to provide high-speed driving. Although the motor does all the work, it is the gears that would determine if your vehicle is targeted to provide a lot of torque or a lot of BHP.
1. Torque is a measurable quantity, while BHP is simply calculated from torque and RPM
2. Torque is much easier to relate to acceleration and force compared to BHP 3. BHP is much easier to relate to speed compared to torque