Abstract
With the advance of simulation technology in recent years, studies to enhance development efficiency have been carried out in the area of vehicle design. The authors have developed CAD/CAM/CAE linking system for ports, aiming to shorten the motorcycle development period by changing the design process. The characteristic of the system is the capability to easily prepare a 3-dimensional shape data of the port, and a simulation and NC machining can be conducted using the same data. The simulation was used for a prediction of effective open area which means mass flow rate in steady flow. The simulation result showed an adequate accuracy and similar tendency for practical use compared with actual measurement. The system contributes to the reduction of man-hours in the port performance test at an earlier stage of development to decide a port shape.