a writes:

Here is a clue. Peak egt is different for different power settings,
and too high an exhaust gas temperature can do bad things to valves
and pistons. Highest temps occur near peak power. We control the
temperature by adjusting the mixture so there is less than
stoichometric combustion to keep those temperatures controlled.

Hmm ... okay. Somehow I was thinking that peak EGT would always be the _same_
temperature, but that's not necessarily true--it would simply be the maximum
temperature for a specific situation. So the peak EGT for max pressure and
RPM would not necessarily be the same temperature as peak EGT for modern
pressure and RPM, and the former might be too high for internal components,
whereas the latter would not.

Does that make sense?

I'm amazed at all the complications of piston engines on small aircraft. Big
jets used to have a flight engineer with a whole panel of controls and
instruments, but they managed to eliminate that with various forms of
automatic and engine design changes. And yet the same has not happened on
small aircraft: you practically have to be a mechanic to be a pilot, at least
in small piston aircraft. It seems like a hazardous distraction--a pilot
should be able to dedicate himself to flying, not to tweaking an engine.