I’ve been a CAR reader and subscriber since 1962, which equates to having read some 640 issues. I have for some time, however, been tormented by a torque-related conundrum: I’ve noted that certain similar engines, particularly within the VW range, produce the same power but have different torque values. What bothers me is whether those with higher torque outputs suffer a sacrifice somewhere within their performance range?
TONY STEENEKAMP
Cape Town
Thanks for being such a loyal supporter, Tony! What is important to remember is that power (kW) is a function of torque (N.m) and engine speed. A typical torque curve against engine speed starts low and then reaches a peak somewhere in the middle of the engine-speed range before tapering off towards the higher engine-speed range.
The maximum power on most engines is produced high up the engine-speed range, even though the torque figure drops, as the increasing engine speed more than makes up for the drop in torques. Therefore, it is theoretically possible for an engine with a high torque value in the mid engine-speed range to have a similar maximum power figure than an engine producing less torque in the mid engine-speed section but the same amount of torque higher up.
Without variable-valve-timing technology in a naturally aspirated petrol engine, engineers can choose to optimise the mid-range torque output for a specific engine, but usually that’s to the detriment of maximum power output because the torque value at higher engine speeds suffers.
