On Jul 4, 7:27 pm, Bob Engelhardt wrote:
What occurs to me is that this could be the solution to the running-lean
problem. Gas engines run way richer than they need to, 'cause running
lean gets too hot.

Not so much anymore. With computerized fuel injection and
knock sensors and the like, mixtures are about as lean as you can get,
I think. Aircraft engines, being air-cooled, will consume much more
fuel at high power settings just to cool them, but in cruise we can
lean them (manually) to the lean side of Peak Exhaust Temperature and
get better mileage. The key there is injection that's uniform
(difficult to achieve with the mechanical systems used on aircraft,
and the primitive induction systems) and lower power settings, usually
65% or so.
Computerized systems are a ways off for aircraft. The
reliability of such stuff isn't good enough yet and requires too many
backup systems. But they sure do the trick in autos.

Dan