I think that you are quite far away from being able to understand this.
To the depths of what could be known about thermodynamic, yes, I probably am.
I approve design changes to Lycoming and Continental engines, as well as certain aircraft, I don't pretend to be an expert in thermodynamics. As with anything, any aspect can be taken to much greater depths of understanding, in most cases at the expense of understanding another associated discipline to great depths.
If your reaction is No No No No - why is it not possible for an ordinary person to figure this out - then have a go at designing an atomic bomb, or a jet engine.
No No No No, I'm quite happy testing and approving small aircraft modifications. No need of atomic weapons. I am delighted to think that an ordinary person might want to expand their understanding, and am always happy to help a little. The question askers of today, could be the innovators of tomorrow - and we need to encourage them!
Of course a perfectly ordinary person CAN do these things given a decade of study
Yeah, that sounds about right, based upon the experience it took me to be granted Transport Canada Design Approval Representative delegation for piston powerplants
I don't mean to be rude
Oh, okay, I misunderstood..
do manufacturers provide an indication of the thermal efficiency of each engine, or does it varies based on power setting?
Baobab,
I have reviewed the Lycoming IO-390 Operator's Manual, which I'm sure would represent the "latest and greatest" from Lycoming. Though it presents lots of interesting written and charted information, it dd not mention thermal efficiency. There was lots of charted information about performance relative to power setting.
Don't let negative writers put you off... Your questions seem well considered to me.