For many years, compression ignition combustion has been studied by a combination of generic studies on fuel spray formation and analysis of results from single and multicylinder engines. The results and insight have been applied to design and develop advanced fuel injection equipment for high-speed direct injection engines. Experimental fuel injection equipments, including early common rail designs, have been matched to combustion chambers in single cylinder research engines to tackle the conflicting requirements of efficiency and minimum nitric oxide formation, combustion noise and soot. A clear strategy evolved from the work with experimental equipment that is being applied to multicylinder engines. If sufficient oxygen is available in the gas charge trapped in each cylinder, the LDCR common rail injection system will provide the fuel required to develop high torque at low engine speeds. Rate modulation reduces noise, unburned hydrocarbon and nitrogen oxide emissions to meet the emissions limits in Europe (Euro III), with low fuel consumption. This is due in a large part to the rapid actuation of the control valves and rapid response of the nozzle in the LDCR injectors.