A study of the fundamental design characteristics of SI engine inlet ports is presented. The work involved the parameterisation of inlet port design features to enable a simplified description of the fundamental form of a port to be made.A parametrically controlled CAD model was then created to enable variations in port geometry to be generated quickly and surface meshes created for CFD analysis. CFD analysis and Design of Experiments were employed to establish the relationship between design parameters and port flow characteristics. Correlation of the CFD results was established via the use of a number of rapid prototype port models, tested on a flow bench.To aid interpretation of the data, a computer emulation of the results with a Graphical User Interface (GUI) was produced using MATLAB software.The resultant GUI is available for use as a tool to highlight the effects of key design parameters during the concept and optimisation stages of inlet port design. The process can also be used to aid the design and development of other flow related systems.