Principle, increasing engine speed

Fig 1: Identifying Principle, Increasing Engine Speed

Courtesy of SAAB-SCANIA OF AMERICA, INC.

The principle is that the degree of advanced ignition must increase as the engine speed increases or the combustion pressure will build up too late. This would result in poor engine efficiency and exhaust temperature.

Early ignition of the fuel/air mixture would cause pressure to build up too soon, resulting in lower output but increased knock sensitivity.