Concensus on RCM is that Mamba Max ESC, 8L motor, and 3S seems to be the sweet spot for the CRT.5. That motor and battery combo geared to only 33mph seems to be well undergeared. If you are driving on a tight track it will be great, but you can easily gear up or run 2.2 truck tires and increase your top speed without much of a heat issue.
My CRT.5 runs a Novak GTB esc, Novak 6.5 (6400kv) motor, and 4800 2S batts. I don't have any heat issues at all and that's geared for 40+mph (46/12 or 13) with 2.2 truck tires. I run a fan on the esc (probably doesn't need it) and no heatsink on the motor. IMO the aluminum motor mount and chassis act as a great heatsink for the motor.
I run a MM and Hacker 8L (almost identical to the Feiago 8L in kv) on 3s in my CRT.5 and it is a wicked little truck. When bashing or parking lot racing it runs with the 1/8 buggies no problem. I have been running a 20T pinion with no heat issues. Its good for mid 40s.
On the track though the 3s is a bit much. I litterally just throw in a 2s pack and its perfect. No regearing needed.
I can't decide if its more fun
to make it...
or break it...