Semin , Rosli Abu Bakar , Abdul Rahim Ismail , Air Flow Analysis of Four Stroke Direct Injection Diesel Engines Based on Air Pressure Input and L/D Ratio, Research Journal of Applied Sciences, Volume 2,Issue 11, 2007, Pages 1135-1142, ISSN 1815-932x, rjasci.2007.1135.1142, (https://makhillpublications.co/view-article.php?doi=rjasci.2007.1135.1142) Abstract: The air flow through engines is equally important to have accurate values for coefficients of discharge through the combinations of valves, ports and ducts of engines. In this air flow analysis is investigated of air flow is desirable for intake flow through the exhaust flow port using SuperFlow Flowbench. The air flow of the diesel engines can be quite measured under steady flow conditions for a range of pressures and valve Lift per Diameter (L/D). This syudy presents experimental results for air flow investigating in the intake and exhaust flow port of four stroke direct injection diesel engines. The airflow measurements and calculation are shown for various pressures, valve Lift per Diameters (L/D) ratio conditions at the intake port pipe to cylinder and cylinder to exhaust port pipe geometries. The result shown that, the increasing pressure input in port flow on fixed valve L/D can increase the air flow through engine cylinder. Keywords: Coefficient of discharge;correction test flow;test pressure;valve lift;diesel engines