Abstract: Automatic octane measurements are made very rapidly with standard test engine using an all-electronic control that automatically lowers the fuel-air ratio to bring the knock intensity below standard, then automatically adjusts the compression to bring the knock intensity to standard, then intermittently increases the fuel-air ratio, after the first or second intermittent increase permits automatic compensatory compression changes only in the decreasing direction to compensate for departures from standard knock intensity and conducts these compensatory compression changes at a rate too slow for adequate compensation if the fuel-air ratio increase causes a substantial increase in knock intensity, and then indicating the compression ratio reading after the knock intensity remains standard during two to four successive fuel-air ratio increases.

Abstract: Automatic octane measurements are made very rapidly with standard test engine using an all-electronic control that automatically lowers the fuel-air ratio to bring the knock intensity below standard, then automatically adjusts the compression to bring the knock intensity to standard, then intermittently increases the fuel-air ratio, after the first or second intermittent increase permits automatic compensatory compression changes only in the decreasing direction to compensate for departures from standard knock intensity and conducts these compensatory compression changes at a rate too slow for adequate compensation if the fuel-air ratio increase causes a substantial increase in knock intensity, and then indicating the compression ratio reading after the knock intensity remains standard during two to four successive fuel-air ratio increases.