Thus, the combustion effect is directly determined by quality of mixture. The combustion processes in the combustion chambers with pistons A and D are faster than those of pistons B and C because of the more appropriate distribution and more intense in-cylinder flow. The in-cylinder temperature and pressure on the chambers with pistons A and D rapidly increase, and the peak times of in-cylinder pressure are more appropriate for GDI engines.The combustion chamber with piston D exhibits the highest release of cumulative heat, which is advantageous to the promotion of thermal efficiency. The higher temperatures in the cylinders with pistons A and D increase NOx production, but help reduce soot emission.