<div class="htmlview paragraph">Intensive investigation of the theory of the Stirling engine system and of problems such as crank systems and gas sealing have made possible the prediction of properties of a given design within a few percent. This paper describes a test system in which properties of engines with high power per cylinder can be measured elegantly and cheaply. The large number of parameters determined over a large range now permit optimization programs to be run on a computer. Construction details are given and reversibility of the system is demonstrated.</div>