[supercat]

Piston gasoline engines beat out Steamers.

In what way is the piston engine inferior to a steamer? While continuous combustion has definite advantages over pulsed combustion, a steam engine is limited by the ability to transfer heat into the steam.

An approach I'd like to see used would be to combine the concepts of internal- and external-combustion engines by having an engine where fuel and air are pumped into a combustion chamber and the combustion products power a piston engine (which in turn powers the pumps). I would think that there would be a potential for quite reasonable efficiency in such a system (this principle, btw, is how turbine jet engines work).

[bvw]

Good points. And many steam engines are piston driven -- such as the old railroad locomotive.

However a gasoline internal combustion piston engine has the following drawbacks:

• Thermal cycling in the combustion cycle.
  
• High thermal gradients due to the heat of combustion.
  
• Shock effects of the supersonic combustion front. (Honestly I don't know if the combustion is supersonic, I'm guessing, I could look it up ... I did know this at one time ...)
  
• Run down gasoline dissolves cyclinder lubircant layer.
  
• Hi-temp by-product hard salt and oxide build-up in the combustion chamber.
  
• Gasoline vapors hard to deal with.