Optimization of Intake Port for Improvement of Fuel Consumption and Torque

In this study on the motorcycle engine, we investigated the geometry of the newly developed intake port with an objective of improving the fuel consumption and the torque in practical range. Herein we present the results obtained. We believe that an effective measure for achieving the stated objective is to improve the combustion speed and combustion stability. To realize that, it is necessary to increase the turbulence during combustion and improve the homogeneity of air-fuel mixture. To investigate the feasible shape of the port, the CFD simulation (including fuel spray analysis) was performed and a geometry that improved the turbulent kinetic energy and mixture homogeneity at the time of ignition was selected.

For confirming the combustion improvement effect achieved by tumble strengthening, an engine test was conducted with the same amount of intake air as that used in. Analysis of the heat release rate calculated from the pressure in the cylinder revealed that an improvement in the burning rate and combustion was achieved by adopting the newly developed intake port shape. As a result of the above approach, by improving the turbulent kinetic energy and the homogeneity of the air-fuel mixture, the fuel efficiency has been improved and the torque also improved in the practical range.