Until 1972, the engine power was expressed in hp (horsepower). From 1972, kW (kilo-watt) was used. At that time the calculation base for hp was very different in the different countries. In America, the SAE-hp were common. By the use of unrealistic measuring methods, in which the motors ran on the test stand without auxiliary units, particularly high performance values could be specified.
While the Perkins engines were listed with DIN-hp in the Storebro price list, Volvo-Penta liked to use the SAE-hp.
With the change of the Swedish price list from no. 48 (1975) to no. 49 (1976) Storebro used the same unit for all engines. These now refer to the performance on the propeller shaft.
The new values made the popular Volvo Penta MD32 appear in a new light. The really much lower performance compared to the Perkins engines, in particular to the supposedly comparable Perkins 115, finally explained the large difference in the driving performance.
Another issue of performance was the difference between the flywheel performance and the propeller shaft power. With newer engines in the range of 300-400 hp, the loss is about 5 to 20 hp. This value depends on the type of gearbox installed.