AA5BY, as I posted in another thread years ago, you have proved my point, that Blade Diameter & Pitch Thrust are not equal to each other in loading an engine, meaning that more pitch does not load an engine equally to the way Prop Diameter does,
so more Flywheel Effect is what you have achieved with your larger diameter prop,
in my mind, I feel most people are Peak RPM oriented, meaning they think "the more RPM, the better" I know I can think like that because I like to fly fast for the most part, yet along with more flywheel effect a larger diameter prop also smooths out an engine (a better running engine run smoother), and a Hotter Glow plug burns more fuel at lower RPM than a Colder Glow Plug does, so a larger diameter prop and the hotter glow plug work well together,, after all, if a given prop is hard to turn it will turn easier when burning more fuel ,
also know, a given engine's peak Torque point is where that engine is most efficient. and most engines peak Torque point is below peak RPM.
so a larger diameter prop turns slower because it's harder to turn than a shorter prop, and a hotter plug burns more fuel at lower RPM because it starts the Flame Front sooner, it's a win-win for a Saito because Saito's love larger props,
so with all that I have to now wonder, just how well your engine will run with that larger diameter prop on Glow Fuel with also adding Hotter Glow Plugs than you ran before,
I'm not expecting you to do more testing, just talking, you know..
Jim
BTW, I have a Saito 100 Twin, I have not yet run it or put it in a plane, but I plan to..