This paper presents a simulation of a Marnoch heat engine prototype made using Ptolemy II, an actor actor-oriented design software. The objective of the simulation is to be useable in helping to design and predict the performance of Marnoch heat engines in a variety of applications. The simulation contains over 40 customizable parameters which allows for easy modification for different applications. Data collected from the current prototype was compared to the results of the simulation. The simulation was found to accurately model the pressure characteristics of the prototype.