Designing a Miniature Engine for Large-Engine Performance

The challenge of designing a very small cylinder for a high-performance four-stroke-cycle, avgas-fueled spark-ignition engine is described. Measures for minimizing the performance compromises associated with severely down-scaled cylinder geometry are indicated. A Burt McCollum sleeve valve is shown to facilitate a favorable four-stroke-cycle combustion chamber layout. A single-cylinder engine is featured with synchronized port fuel injection, variable energy CD ignition, top-cold liquid cooling, seal-less centrifugal coolant pump, dry-sump pressure lubrication and one-piece connecting rod with plain bearings. Actual size and weight figures are given. The shaft output and fuel consumption estimates presented are derived from computer simulation.