Hey Peter,
I'm glad your motor heat rise problem is solved. I think a lot of motor heat rise problems can be traced to a general lack of airflow over the motor case.
In our V4 Contra design we are trying to mitigate this problem in a number of ways:
1/.. We have air vent slots in the base of the rear hub that allow cool air to flow through the spinner and into the nose of the plane.
2/.. The gearcase has a considerably smaller diameter, and is coned at the rear to give air flow a direct path to the motor case.
3/.. We are going to put vent holes in the front motor plate to do the same.
Our hope is that with these changes heat rise won't be a problem with any properly designed motor.
Brenner ...