Google 'specific heat of oil vs water'. There's good reason you almost never see oil as the primary cooling fluid. (Though I did have a 1970 Alfa Romeo Spyder that gave it a shot, before I pulled the head to install the missing O-rings in all the block-to-head oil passages.)
I think we've discussed this here in the past; a single rotor rotary pays a big weight penalty compared to a 2 rotor, due to balance requirements. It'll likely pay another penalty in the reduction drive, due to increased weight requirements in the flywheel, 'damper' assemblies, and gears, because of the higher and lower frequency peak-to-average torque pulses.
Charlie
Deutz in Cologne produces some industrial engines with oil instead of water as cooling fluid, about heat transport features, the 'BOSCH Manual of Automobile technique' includes data about most materials used in automobiles; from the heat transport, viscosity, specific gravity properties of oil and water, you can calculate the pump, the radiator,...
Old twin-flat Citroën Series A cars engines (2CV, Ami, Dyane, Mehari) had Air Cooled cylinders, but some parts had oil cooling, with the help of a pump and a radiator. The Voisin designed 'Biscooter' micro-


car, all aluminum, there was aluminum surplus after WW II, with a 2-Strokes engine, had a large engine head, filled with oil, to avoid too much cooling and shock cooling on highway, overheating in traffic lights, oil acting as a 'heat buffer'.
OMC had hard chrome working surface in their Snowmobile Wankel RCEs, it seems was deposited by electric means; after layer was complete, they reversed polarity for some 15-20 min, in order of having porosity in working surface allowing lubricating oil to attach. Suzuki seems used a flame sprayed technology, from Canadian patents by Alfred P Grazen; NSU, Comotor, had nikasil.
About torque steadiness in a single rotor Wankel, it are comparable to a three cylinder engine, it's not that good as a twin-rotor, having the torque uniformity of a 6 cylinder engine, but is good enough, Daewoo and other carmakers offer three cylinder engines, no specific complaints.
The advantage in a single rotor Wankel is with its reduced displacement compared to units with more discs, chances are most time engine will be working in a favorable BMEP environment, and this is a core element in economy and emissions.
An ordinary auto, running on a flat road at 55 mph may use no more than 25 HP, please read:
+ 'How much overall energy does the Automobile require?', SAE Journal Automotive Engineering, vol 80, n 7, pp 36-38, Jul 1972
+ 'How much Energy is needed to produce an Automobile?', SAE Journal Automotive Engineering, vol 80, n 7, pp 39-40, Jul 1972.
+ SAE paper 2013-32-9161: 'The Intake and Exhaust Pipe effect on Rotary Engine performance', from Taiwan.
About power needs in airplanes, lots of references and charts were added in this HomebuiltAirplanes.com site.
The 'How green is green energy?' article is from Scientific American (SciAm)
Blessings +

