<div class="htmlview paragraph">MANY MULTI STAGE pressure charging techniques are being applied to spark ignition engines in the quest for maximum power and Fuel efficiency with minimum weight, space and cost. This paper describes the experience gained by Lotus Engineering from the application of an axial compressor as the first stage of a compound pressure charging system. Attention will be centred around the practical aspects of developing the assemblies once in hardware, to perform in the manner for which they were intended.</div> <div class="htmlview paragraph">The design techniques for matching the various air pumping machines used, namely axial and centrifugal compressors with a reciprocating piston engine are well documented. Rather the evolution of the system is described, from basic design requirements through rig test evaluation, and then final performance assessment.</div>