Abstract: The present invention is a heat engine that has two piston assemblies and a center assembly between the piston assemblies. The heat engine uses a working fluid. The center assembly includes an outside wall and two end walls forming a sealed assembly. The center assembly includes two compression chambers internally. The piston assemblies are attached to the end walls of the center assembly in a sealed condition. The piston assemblies include a burner, piston cavity, piston with piston head and piston shaft. The piston shafts of the pistons are interconnected to each other. The burner is in contact with the piston cavities. There is also a heat exchanger connected to the center assembly and piston assemblies.