An open-cycle engine approximating the Stirling cycle but retaining external combustion is being developed. The Stirling engine is being built on a motorcycle V-engine; however, the heat exchangers have been designed from scratch. Some thermodynamic considerations justifying the use of the open cycle are presented. A numerical simulation of the proposed open cycle is described. An optimization of the heat exchanging system, making the use of an entropic parameter, is attempted, and the results are presented. The design of the experimental motor has been completed and is waiting for experimental testing to verify the cycle effectiveness and the optimization criteria. >