Abstract
The two serious problems of pollution from diesel engine exhaust gas are smoke and NOx. It is possible to improve the engine efficiency, normally by control air temperature and moisture and also fuel temperature conditions. Both high atomization fuel injection and increasing air density are the basic for improving engine efficiency. In this experiment, both air and fuel were controlled in various conditions. The result shown that the engine had been decreased the efficiency and had more stringent regulation of smoke, particulate, and NOx if increase moisture content or air temperature but NOx decreased when more moisture condition. If increase fuel temperature, the results is not only obtained better engine performance but also better emission.