Make your fan stay hard throughout the race !!! This will continuously supply an 8V to the RC cooling fan of your choice. Making your motor cools all the time.
 
Normally if you contact your fan to your receiver for power, you get a 6V supply below the best operating voltage of most RC fan, leaving lots of cooling power on the table.
 
Or if you connect your RC fan power to the battery,  as the car runs, voltage drops, so as your motor gets hot, yet your cooling power also drops, It is not a nice scenario.