Ragsf15e,
Thank you for the reply. I generally fly in the 7,500-9,500 range with the prop at 2,500. The lean of peak is an interesting topic as well. The POH does give a max cruise and max efficiency mixture setting, however, they are both on the rich of peak side, one at 100 degrees and the other 25 degree rich of peak. Is it common practice to operate lean of peak when the POH only uses rich of peak? When you mention the airflow at WOT is at the most efficient, what do you mean? Airflow through the engine?