In the recent decades, global warming and climate changes have persuaded engineers to improve the design of internal combustion engines in case of pollutant emissions and efficiency. The injection system is one of the main subsystems which can highly affect the quality of mixing process inside the combustion chamber and result in higher efficiency and lower emission. Winterthur Gas & Diesel, which is a manufacturer of marine diesel engines, has come with an idea to improve injection process. The idea is that to remove sharp edges at the entrance of the nozzle orifice and increase its roundness to improve the discharge coefficient and decreasing the vapor volume, which is formed by cavitation.