Some Effects of Fuels and Lubricants on Autoignition in Cars on the Road 540222
STUDIES of cars on the road show that both fuel and lubricant characteristics affect the occurrence of autoignition.
For instance it is indicated that autoignition can be eliminated by increasing the fuel antiknock quality, although the Research octane number required may vary slightly depending on fuel composition. Limited evidence is also presented to indicate that aromatic constituents of gasoline are somewhat less effective in suppressing autoignition than are paraffin hydrocarbons.
In addition, it is shown that differences in autoignition tendency are observed when different fuels and lubricants are used during the deposit buildup period. In one series of tests a difference of seven octane numbers was observed between autoignition tendencies resulting from operation with different lubricants.
Further tests indicate that the addition of the amount of tricresyl phosphate theoretically required to convert all the lead in the fuel to lead phosphates lowers the Research octane number required to eliminate autoignition by about three octane numbers.