This proposal outlines an SBIR Phase I engine project capable of diesel fuel operation and lightweight construction. Inherent specific weight penalties of the diesel cycle being inversely proportional to specific displacement, indicates a scale reduction of these engines demands greater design discipline relative to the physics that govern their performance. The proposed approach employs a combination of innovative translations of rotary to reciprocating motion resulting in a compact design of high mechanical efficiency. Additional power-producing volumetric valving controls swirl and scavenging efficiency, enabling high bmep levels. High thermal efficiency is achieved by the incorporation of low surface/volume geometry. The design makes extensive use of synergism.