Paul :
       My intuition is that, if Wankel produces such high temperatures, it is not because of its design but because it actually works like a two stroke engine.  Were this  the case, the solution would be changing the cycles (both thermic and mechanic) and not by simply increasing the quantity of oil and/or by increasing the radiator/s surface. EB.                               
I have no idea what you are talking about. The Wankel works as a four
stroke no if and or butts.

One of the reasons the exhaust is hot is there are no exhaust
valves to absorb heat. In a piston engine e 20% of the exhaust
heat goes into the exhaust valves tending to destroy them.
http://www.rotaryeng.net/turbo-compound.html


That is why the FAA wants you to check the valve leakage
every year or every 50 hours in your piston aircraft engine.


Paul Lamar