Inlet port flow characteristics are critical in determining the overall performance of diesel combustion systems. The relationship between inlet port geometry and performance has long been a subject of interest to many researchers, although as yet a comprehensive understanding remains elusive. The ongoing need to provide advanced powertrain design solutions in order to meet increasingly stringent emissions legislation, whilst meeting customer expectations and minimising engineering costs, has driven the development of new approaches to engine design. In particular, the fundamental advantages of multivalve technology, coupled with rapidly improving fuel delivery systems has placed new requirements on inlet port performance characteristics. Statistical methods and knowledge-based design are emerging as potentially powerful tools in this field of research, supported by rapid developments in computing power.