An engine’s power is measured by running the engine against a load on a dynamometer. The braking effort needed to hold the engine at a steady speed on full throttle gives the torque. The power can then be calculated by multiplying the torque by the engine speed.
An engine which produces a lot of torque over a wide range of engine speeds
will be relaxing to drive because fewer gearchanges are needed: the engine’s
torque is often sufficient to accelerate the car without changing down. At
cruising speeds a lorquey’ engine will not need to be turning over very quickly
because it can pull at high gearing, which makes for good
economy.
Engines that produce a lot of power for their size do not usually produce so
much torque, and what torque there is is often produced at higher engine
speeds. It is also likely that the engine will be producing usable torque and
power over a smaller range of engine speeds; this narrow ‘power band‘ makes the
engine less suitable than a torquey or ‘lazy’ engine for jobs such as towing,
and the car will be less relaxing to drive.