Nylon is strong and definitely use it if you can. Carbon fiber in a filament has no structural advantages at all, it's just for color. It doesn't even look like carbon fiber.
This is just so wrong.
Carbon Fiber has no structural advantage?
Why do you think they put chopped up carbon fiber in plastics in the 1st place?
Because they introduce structural advantages and benefits to the combined. material. Synergy.
MY comment on whether it would make a good motor material. Probably not.
It wouldn't hurt to consider PC/CF, or PEKK/CF.
But then you gotta have a drying box, a heated enclosure and be able to print at 290C to 340C. Ouch