The Effects of Refinery Gasoline Components on Road Octane Quality

Thirty-five unleaded and nineteen leaded gasoline blends were tested for road octane rating in a fleet of nine unleaded cars or seven leaded cars as applicable. These blends were prepared to cover a wide range of composition while meeting octane targets and volatility specifications. Road octane results were closely related to (R+M)/2 for unleaded gasolines but Motor octane was more important than Research for leaded gasolines. The effects of component composition on deviations from road octane correlations were small.

Unleaded component effects not predicted by laboratory octane number were obtained in a single manual transmission car; those effects are attributed to octane distribution over the gasoline boiling range.