One of the instant ways to improve engine performance is to tune in the intake port. One of the tunings in the intake port is by polishing the intake port and adding dimple. This impact can increase the engine performance due to an increase in the turbulence intensity of flow. The mixture of air and fuel in the combustion chamber will be more homogeneous and the flow will be more turbulent, thus leading to the small friction loss. This research focuses on the design of the intake port to increase the turbulence intensity of flow with variations of dimple depth and arc length of dimple distance. The present study aims to improve the engine performance through the optimization of dimple diameter and arc length between dimples. The results of Computational Fluid Dynamics (CFD) show that the dimple depth of 1.5 mm with an arc length of dimple distance of 7˚ can produce the turbulence intensity greater than 10%. When the design is applied to the Honda CRF 180, the power increase is 12.25%, and there is an increase in the torque of 1.46% to the standard intake port.
