Engine Torque

What is Engine Torque? It’s Characteristics & Formula

 | 6 minutes read

Engine Torque Definition and Formula:

What is Engine Torque?

Torque, in simple terms, is ‘Twisting or Turning Force’. It is the tendency of a force to rotate an object about an axis. In automotive terms, it is the measure of rotational effort applied on engine crankshaft by the piston.

Torque= Force x Distance. The SI system uses Newton-metre (Nm) to measure the torque. The other units are kilogram-meter (Kg-m) in metric and feet-pound-force’ (ft-lb) in imperial / British units.

Torque Definition Diagram
Torque Definition Diagram

Every engine is designed and built for a specific purpose. Hence, its output varies depending upon its application. The torque output of an automotive engine mainly depends on its stroke-to-bore ratio, compression ratio, combustion pressures & speed in rpm. Most ‘under-square’ engines which have higher stroke-length than its bore diameter, tend to develop the high amount of ‘low-end torque’. The amount of torque that an engine can exert depends upon the engine RPM.

Different engine designs/configurations develop different torque characteristics such as peak curve/flat curve. Most automotive engines produce useful torque output within a narrow band of the engine’s entire speed range. In petrol engines, it characteristically starts at around 1000-1200 rpm and reaching a peak in the range of 2,500–4,000 rpm. Whereas in a diesel engine, it starts at around 1500-1700 rpm and peaking at 2000-3000 rpm. Bugatti Veyron is one of the cars with the highest torque figures.

Engine Torque Graph
Engine Torque Graph

How to calculate engine torque:

If you know the Horse-Power of the engine, then you can use the following formula -

Don't miss out on Automotive Knowledge