The PRECISION of MOTOR FUEL TESTING - Report from Cooperative Fuel Research Committee

THIS third triennial analysis of the precision of motor fuel testing is based on 6925 knock ratings on 183 fuels, and inspection data on 109 of these fuels. The analysis shows that the precision of rating by both ASTM Motor and CFR Research Methods has continued to improve during the last three years, the standard deviations for both methods now being below ½ octane unit. It appears possible for these deviations to be reduced to half of this value.

The humidity control apparatus is shown to have no direct effect on ratings. For the first time, the analysis includes fuel inspection data, and estimates of precision are given for vapor pressure, gravity, and distillation measurements.