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The effects of injection timing, ignition timing, and injection nozzle parameters on the regulated emissions from a high-compression ratio direct-injection spark-ignition methanol engine were investigated experimentally and its emission characteristics were compared with the diesel counterpart. The experimental results indicated that the injection and ignition timings affect exhaust emissions significantly. Best compromises between the brake thermal efficiency and three emission pollutants at the optimal injection and ignition timings were obtained. The effects of injection nozzle parameters on emissions of methanol engine are significant. The THC (total hydrocarbon compounds) emission using an injector of a 10-hole × 0.30 mm nozzle is lower significantly than those of 7-hole × 0.45 mm nozzle in the overall load range and CO (carbon monoxide) emission is also lower, but NO_x (nitrogen oxides) emission is higher at …