Abstract
Six-stroke diesel engine proposed here has two combustion processes in one cycle, i.e. intake, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. However, soot and CO emission increased due to weak swirl in combustion chamber at 2nd combustion process. In this study, swirl ratio was increased in order to improve the 2nd combustion process. In the high swirl ratio case, exhausted soot, CO and NO were reduced when air was introduced into the cylinder between the 1st and 2nd combustions by modifying valve timing. It seems that, therefore, the high swirl ratio with the valve timing modification could improve the mixing in the 2nd combustion.
