Walter, once again thanks
So, I'm planning to try this instead of my old 75% cruise climb.
35"/2575. This will be about 90% power - full fine and 5" back from the top of the green. However, it a) gives some headroom to max MP which can be easily exceeded and b) by the CMI graph puts me in a more efficient BSFC area.
I'm going to set about the CMI KB " full Rich" flow (70 litres/hr), then check the TIT and lean further to 1250 degF TIT - 1300 degF TIT (with the caveat's about CHT).
Cruise is more interesting.
I have never been able to achieve the CMI fuel flows. I have a deep suspicion that despite their "prohibition" on fuel flows leaner than 25 degF ROP TIT that in fact the economy fuel flows that they publish are maybe 25 degF LOP TIT.
This would explain why I can't get there, because I stop at 1650 degF TIT. Getting to LOP requires going though the 1650 TIT limit.
I couldn't sleep last night and was fooling around in the NASA Langley library. There is nearly nothing those guys didn't research in the seventies. Including running a TSIO 540 with hydrogen injection. UNFKNBLVBL. They hung a hydrogen generator out in the slipstream. But they made some baseline measurements on pure AVGAS that are informative.
There's also a paper on a TSIO 360 with oxygen injection to reduce exhaust emissions. But unfortunately, they only tables emissions data, not engine operating conditions.
But, particularly the Lyc TSIO 540 graphs helped me understand the behavior of TIT better. So my plan is to try 65% power and do what CMI say and lean to a fuel flow and see what happens. I think maybe it might go through peak TIT to 25 - 50 degF TIT LOP. In which case its probably a pretty good place to be.