Relation Between Engine RPM and Engine Torque

To understand this behavior, you need to understand one more term which is called as “ Low-End torque”. Low -End Torque is the amount of torque produced at Low RPM range of an engine ( around 1000–2000 rpm) .This low end torque is very crucial when moving a vehicle from stand-still or driving in slow-speed conditions such as in traffic. If the greater amount of torque is generated at the lower end of engine rpm, it implies that the engine has more ‘low-end-torque’ or better pulling ability at slow speeds.

It also implies that vehicle can move very quickly from rest/stand still.

Now as the engine speed keeps increasing, torque starts to decrease because of the increase in friction between engine’s moving parts.

Engine torque is also related to the gearing. The lower the gear, greater is the pulling ability of an engine and hence greater the torque..

If you know the Horsepower (HP) of an engine, then you can calculate the torque using the formula :-

Torque = (HP*5252)/RPM