Hi,Just my 2c, the C50 you are using does not have built in fan.The C50 comp. does have a fan.Given this you need more flow than the Comp motor requires.Also the foam piece you have across the motor will stop airflow not encourage it,the baffles must have some angle to direct air over the motor and out,not stop airflow at the motor.The recommended max temp of the motor is 60c,the magnets should withstand 160c !!! but there are other considerations,not just the magnets.
How do I know this........................just look at my address,it gets VERY hot here and we have to deal with it!!
So in short:- large air inlets,good baffles and LARGE outlets i.e.3x the inlet area.
Hope this helps.
Dambuster.