Some Observations of Factors Affecting ORI

A review has been made of anomalies that exist in the changes in octane requirement of recent model cars operated for several thousand miles using unleaded gasolines and SE quality oils. A number of laboratory multicylinder engine tests have been conducted to elucidate possible reasons for some of these anomalies. These tests have uncovered mechanical variables that can produce relatively rapid changes in the octane requirement of an engine and octane requirement differences between engines of the same make and model, operated on identical combinations of gasoline and oil. Two of the more important variables are the initial octane requirement and the amount of oil migrating to individual cylinders in the engine.