By running some engines for millions of hours at around 30 degrees rich of peak and running other engines for millions of hours at around 30 degrees lean of peak, then comparing the reliability of each group.
If only that had happened around 50 or 60 years ago.
Oh, wait....
Are those the same engines where according to flight engineers notes, they advanced timing from 20 to 30 degrees BTDC which favoured improved valve life when running leaner than 0.077 (which seems to correspond to about 50 ROP)?
R-4360Ops1
Also, interestingly, the target CHT was 230C (445F) which is high compared to the numbers people worry about here. I have no idea whether the materials are the same - but if they are different, it is another reason why the data may not be directly applicable.
Walter, in post 193:
One must be careful in comparing these engines and their engineering requirements to our GA engines.
Science is inconvenient: if your proposition is that data collected from large radials is equally applicable to today's GA engines, the question becomes how do you test
that?