Different power sections of American EPA Tier4 non-road diesel engines of under 37 kW were analyzed. Low-emissions technical routes applied to foreign and domestic small power non-road diesel engines were discussed and analyzed based on the work done in implementing China Ⅲ emissions standard for non-road diesel engines. According to the present situation of China

the following technical routes were proposed to make engines of under 37 kW meet China Ⅲ and the future emissions standard: optimizing mechanics together with DOC after-treatment technology or with electronic fuel injection technology to improve combustion process and reduce oil consumption

improving production conditions and strengthening quality control

especially effective control in the maximum fuel delivery at full load so that engines from mass production can meet the China Ⅲ and China Ⅳ emissions standards. Moreover

in order to effectively control engine emissions and performances and to meet stricter emissions standards

it is necessary to develop low emissions technology for small multi-cylinder non-road diesel engines of 15 kW to 37 kW and the corresponding products.