A combustion system has been developed to burn neat (pure) methanol in a direct-injection four-stroke-cycle engine. Primary objectives were to obtain low fuel consumption and long component life to make the engine suitable to replace heavy-duty diesel fueled engines. A glow plug was placed in a modified quiescent combustion chamber to ensure reliable methanol ignition at all engine operating conditions.The methanol engine provides thermal efficiency nearly equal to the diesel engine from which it is derived, in addition, nitrogen oxide emissions are reduced by 50 percent and exhaust smoke is negligible. Hydrocarbon emissions are still above the baseline diesel engine.Laboratory and field durability tests of over 2000 hours have been completed. Excellent cold-start capability has been established.