Andy Dingley wrote:

On Sat, 24 Dec 2005 10:15:05 GMT, Johannes
wrote:

That's a bit of an over simplification. Engines don't run at their most
efficient until up to temperature. Probably to do with proper atomisation
of the fuel.


Indeed, this is abstract thermodynamic theory that was fully developed in
the 19'th century.

Why is that particularly relevant though? That deals with the
temperature of the working fluid, not the engine itself. A petrol car
engine might take several minutes to warm up properly, but the
combustion temperature is stable within seconds.

This was in context of my original post; I wanted to emphasise that it
was a generalised assertion of the maximum possible efficiency. Other
factors may reduce the efficiency.