Yup, datalogged information would be best. Pregens run too cold as it is, won't boil off water condensated in crankcase and lead to poor lubrication. Not to mention large delta-T beween combustion-chamber and water-jacket robs power. Honda's done some great research on ceramic engines that run much hotter than current ones, with benefits of more power and efficiency.
Some great graphs of collected data on Thermo Bob site.
Https://shop.watt-man.com/Thermo-Bob...EARS-TB3-N.htm