Interest in alternative diesel fuels has led to consideration of various types of poor ignition quality products, such as a broad cut fuel or a synthetic fuel/DF-2 blend. Attempts were made to expand the cetane number tolerance limit of an EMD 567B medium-speed diesel engine through staged injection to permit operation on such fuels. A small portion of the fuel was injected early in the cycle to act as a pilot for the main fuel charge. Both pilot and main charges were the same fuel. Knocking was eliminated on fuels with cetane numbers as low as 17 at the standard 16:1 compression ratio. Attempts to operate on methanol at 20:1 failed, but such operation may be feasible with further modifications.