LB
I could, if I were stupid enough, drag more than the maximum rated power out of my engine by leaning the mixture to around 25C rich of peak after take off at sea level on an ISA day with full throttle and maximum RPM. However, I’m not that stupid.
You said the engine is certified to run at max rated power continuously to TBO. Again, no it isn’t. It seems you didn’t read my post. The information is freely available from the FAA. A TBO in terms of the certification process, is a recommendation for private pilots and a limit for commercial ops. Either way the engine is not ‘certified’ to make the TBO at rated power or any other power. It is implied that the engine will make TBO if run at the “recommended power setting for maximum service life” - eg 65% for Lycoming.
Your point that “all mixtures are lean”: go on then, explain why in your opinion a full rich mixture is lean, or for that matter why any mixture richer than stoichiometric is ‘lean’.....