DIN 51756-7:1986-02

The determination of the anti-knock characteristics of alcohol and fuels containing alcohols is in principle done in accordance with DIN 51756 part 2 on the CFR-test-engine. DIN 51756 part 7 describes a variation of the original method, namely the use of a controlled needle jet of the carburettor instead of the level control with calibrated horizontal jet for the adjustment of the air-fuel ratio for maximum engine knock. In addition a inlet manifold heating is used in order to adjust the mixture temperature to the greater heat loss during eraporation of alcohols (especially methanol).