With increasing public concern over the environmental problem caused by vehicles, the regulation of exhaust emissions and noise is becoming stringent.Due to its good fuel economy, diesel engines are fitted on all small trucks and coaches in Korea where crude oil is entirely imported.The gasoline engine has drawbacks of poor fuel economy and high CO2 emissions causing “green house effect” but advantage of low noise and well developed anti-pollution technology. Direct injection (DI) diesel engine has good fuel economy, but it has disadvantage of high noise and difficulty to reduce NOx and smoke simultaneously. Indirect injection (IDI) diesel engine is used for all light duty vehicles and trucks in the Korean market where fuel economy is a major concern as well as low emissions. To keep this market with IDI diesel engine, much improvement of emissions, noise and fuel consumption is strongly required.The effects of engine parameters, such as hot plug throat area, glow plug intrusion, clover leaf diameter in piston and geometric injection rate on performance and emissions have been investigated to develop a more improved small IDI diesel engine. This paper describes the experimental results obtained during the study.