Originally Posted by 3rd-dem
I believe a 2800kv is a good 5s motor for most any fan other than the CS! From what I understand the blade count of the CS (10) requires stronger/lower kv motors to be efficient. I have test flown mine (Het 2W-25 2720kv) on 4s and it's a "pleasure".
Some important differences:
Het 2W-25 2720kv is an inrunner - inrunners generally draw less current than outrunners at the same RPM, generate less torque and is more efficient at higher RPM's.
Het 2W-25 2720kv is rated at 1100W with a 6S battery - has no problem when derated at 4S. The HK motor is iffy, in my opinion,
Throw the setup on a wattmeter and see what it pulls from the battery ...