Road Knock Occurrence in Japan

A limited field survey was conducted to determine whether full-throttle acceleration from low engine speed is suitable for road knock tests of fuels in manual-transmission Japanese cars.

Varying knock levels, fuels, cars, and drives were used on a route typical of average Japanese driving. Knock did occur most frequently during full-throttle acceleration from low engine speed. Part throttle knock was encountered, also.

Maximum octane-number requirements of four Japanese cars were measured and were as high or higher at 2 in. Hg manifold vacuum as at full throttle. Four typical Japanese fuels were rated in the cars at both throttle settings. These tests indicated that fuel segregation may be important at both full and part throttle.