Introduction:
The power output of an engine of a vehicle at a specific point that rotates the wheels or twists the whole mechanism from crankshaft to all the way through wheels to move the vehicle on the road is called torque (twisting power). It is produced exactly the same way that the force applied at a distance. In the engine when the combustion incident, it creates pressure against the pistons to produce the power on them to push them back, the force is transferred on the crankshaft through connecting rods. By concentrating on the cycle of the engine you can easily calculate the torque of your vehicle. As the torque is equal to Force multiplied by the Distance, so you essentially need to find the variables of the torque.
1. Find the variables of Torque
There are three main variables of the torque in any engine ie the Force at specific RPMs, Distance and the Constant of the torque. The Force is the horsepower of your engine that you can find on the specific revolutions of the engine or generally the term full motor torque is used to find the force at full RPMs that can typically be found on the engine specification's table. However it can be find by using the horsepower to torque conversion tables. The distance is the length of stroke, longer stroke means more torque generation. Diesel engines produce more torque than the petrol units because the diesel engines use longer stroke bases to compress air into the cylinder. Usually the unit for the torque is used as pound-feet or lb-ft.
2. Calculating the Torque
There is no secret in calculating the torque of the engine, it is just a multiplication of force to the distance from the center of the crankshaft. In general for instance if you have a lug nuts and you have the wrench with a foot long handle and you apply a 100 pounds of force on it than you are simply generating the 100 lb-ft of torque, however if you have two feet long wrench handle and you are applying the same force then you are producing the 200lb-ft of torque with the same force. It was the variable of distance that cause the change in torque at the same power. As we doubled the distance, the torque was automatically doubled. However to calculate the full power torque of the engine you can use the following mathematical formula;
Torque = {Force X 5252} / engine RPMs
Or
T = {HP X 5252} / RPM
Where; T = torque in lb / ft and the HP is the horsepower of the engine however the 5252 is the constant and the RPM are the engine revolutions per minutes.
For example, if your car is producing the 86 HP at the full motor RPMs of 5500 then you can easily calculate the torque for your car at the 5500 RPMs by applying the formula and it would the 82lb / ft of torque.
Warning:
The horsepower is different for different engines and the stroke length can also be different and you need to carefully select the variables to calculate the torque.