An unconventional low heat rejection (LHR) engine design is described. Previous research efforts into LHR concepts, including high temperature materials and tribology, are reviewed. The continued reliance on conventional compression ignition designs is identified as a significant roadblock. Therefore, a set of design criteria is established, and an original design is formulated. The powerplant consists of an independent positive displacement compressor and expander, a high pressure combustor, and a compressed air accumulator. Compatibility with ceramic materials and high temperature combustion were primary goals. Inherent characteristics include full torque from zero RPM, enhanced combustion, improved efficiency under part load operation, and increased volumetric and thermodynamic efficiencies. These potential improvements warrant the design and construction of a prototype for further study.