Good eye, though it&#x27;s not immediately clear that that&#x27;s strictly edging in on Carnot efficiencies or if other aspects (two-stroke power cycle, valveless port-based design, eliminating cylinder-head heat loss -- on which, doesn&#x27;t that eventually reach equilibrium temp <i>anyway</i>?, etc.) are to credit.<p>I&#x27;ve seen a few other radical reciprocating energy designs, there are some interesting YouTube vids I should track down.  I think &quot;radial engine&quot; might reveal something.  New Zealand, possibly Australian engineering firm, IIRC.