Ideal Stirling engines are monomorphic, so the results of the previous chapter apply directly. System charging an ideal Stirling theoretically produces the best possible effect. This is so whether the engine is optimally buffered or not; output increases and mechanical efficiency remains constant.

The Workspace Charging Theorem also applies. Its criteria take a simple form because, for an ideal Stirling, the absolute work ratio equals the temperature ratio:

Thus, if E ² > ?, cyclic shaft work output will increase indefinitely as the workspace is charged higher and higher above a fixed buffer pressure. Of course, mechanical efficiency will certainly decrease after the engine becomes buffered entirely from below.

If, on the other hand, E ² < ?, then shaft output decreases as the workspace is charged above buffer pressure, and eventually the engine will even be unable to run itself. This is just what the Workspace Charging Theorem tells us. Still a question in this case is how output varies in the range just prior to the point where the engine becomes charged above the buffer pressure. This is an important question if one is seeking to improve the performance of an engine by adjusting only its workspace charge level. This question is answered in detail in this chapter for ideal Stirling engines.