An engine that is quite powerful may not be designed to produce its maximum power over long periods.
A gasoline engine in a car may give good acceleration in short bursts, but it can overheat or fail if it’s operated at maximum speed and power for too long.
A heavy-duty diesel engine in a large truck is designed to operate near or at its maximum speed and load for long periods without damage. Many diesels will suffer if they are run on light loads or at low speeds for too long.
One way to describe the power range of an engine is to give its load and speed as an average over a certain period. This is stated as a percentage, and is called Load Factor. An engine required to operate at maximum power over ten hours is said to have a load factor of 100%. Using that as a standard, most car engines would operate at only about 20 to 30%.
