In addition to mechanical difficulties, any engine performance may be affected by other causes, such as engine design and operators performance.

A comparison of the principal conditions which influence the performance of internal combustion engines is given in table 5-1. Note that the performance conditions for the two types of engines (diesel and gasoline) are somewhat similar, except for some differences due to factors dealing with fuel and ignition.

POWER LIMITATIONS

The design of an engine limits the amount of power that an engine can develop. Other limiting

Table 5-1.Factors That Influence Engine Performance

factors are the mean effective pressure, the length of stroke, the cylinder bore, and the number of revolutions per minute (piston speed) of the engine. The latter, piston speed, is limited by the frictional heat and by the inertia of the moving parts.