I'm curious is he runs the world renown NW LA-46 set-up, that being relitively low rpm on a big 'ol 12.25x3.75 prop? Not being critical here, just it seems to me that that set-up may put more stress on the engine than a smaller prop running at a higher RPM.
That is relatively high RPM-myth busted. When I tried that prop on the one I am running, did not run it that high. Maybe a second experiment is in order.
The engine is designed to run 14000 rpm all day long. 9800 isn't very fast compared to that. Brett