Abstract
Meeting the emissions challenge in the medium duty engine class is the subject of a major research programme underway at Ricardo; the ultimate goal is development of a cost effective, low emission, medium duty direct injection (DI) demonstration engine. This paper reports the first stage of the study, which in total will span a period of several years. To date, a six litre DI engine has undergone initial combustion system development using a high pressure sleeve control in-line fuel pump with the objective of demonstrating fundamental requirements for minimum emissions and good economy. The potential for further improvement is considered.