Is Torque King?

krazykuda said
Horsepower is a measurement of work, meaning a force applied to an object and the displacement of that object in the direction of the applied force. What does this mean? One horsepower equals 33,000 pounds-feet per minute (4,562.41 kilogram-meters), or the energy it takes to move a 330-pound (149 kg) object 100 feet (30.5 m) in one minute.

Torque is a twisting force that rotates or turns an object, like a wheel. When you use a lug wrench on a bolt, you're applying torque to it. Unlike horsepower, even if the object doesn't move, torque can still be exerted on it. Torque is measured in pounds-feet, meaning a force in pounds acting on the end of a lever measured in feet. For example, if that lug wrench is 2 feet (0.6 m) long, and you put 100 pounds (45.4 kg) of force on it, you are putting 200 pounds-feet (27.65 kg/m) of torque onto the bolt. Read How Force, Power, Torque and Energy Work for more information on torque.

Once we're able to measure torque, we can then measure horsepower. The formula is simple: Multiply torque by the engine speed (measured in rpm), then divide that by 5,252 to get the horsepower at that rpm level. In other words, to get the horsepower of a vehicle generating 350 pounds-feet of torque at 4,000 rpm, you would calculate (350 X 4,000)/5252, which equals around 267 horsepower. It comes down to this: torque measures how much work is being done and horsepower measures how fast that work is being done.

The torque of a torque wrench is not the same as the torque of a motor. Calling putting force on a wrench without turning it torque is somewhat incorrect. Without the movement the force applied to a wrench is called "bending moment" but is often wrongly just called torque. Torque is the force over a rotating axis, it has to be in motion to be torque. The general physics term "torque" could just be the pressure without movement, but in mechanical engineering, as in a car engine torque has to be in motion.

As I have said 3 times 100 ft-lbs accelerates the car equally at 3000 rpm as it does at 6000 rpmgeneral hough the HP is double. Doing more work, is not accelerating the car at a higher rate. Think of it as working smarter not harder.

The area under the torque curve (not HP) is the way to compare two motors. If the motor makes torque from 2000-6000 that is better then 2000-4000 but 4000-6000 is equal to 2000-4000 even though the 4000-6000 motor shows more horsepower. The 2000-6000 is better not because it will accelerate faster at any given point but that it stays in 1st gear longer multiply the torque longer, and then repeating that again in 2nd, 3rd, etc. But if the motor doesn't start making torque until 4000 rpm the time in each gear will be the same.