The motor is rated at 245kv, so at 24V, we're only talking about 5000RPM max
The Magic Pie has a maximum unloaded speed of ~180rpm @ 24V and has 56 magnets, so the controller will be switching at ~84Hz.
The Turnigy SK3 @ 245rpm/volt = 5880rpm @ 24V and has 12 magnets, so the controller would be switching at ~588Hz, which is seven times faster than it does with the Magic Pie at the same voltage.
To put it another way, the Turnigy SK3 would only achieve a maximum of 840rpm if the controller was switching phases at the same rate as it does with the Magic Pie @ 180rpm
(~84Hz).
It's a bit like overclocking a PC's processor, if you try to speed the operating frequency up too much it will reach a point where it can no longer cope and will become so unstable that it is no longer able to accurately process the data, resulting in so many errors that the system will eventually crash.
If the speed controller's switching frequency is pushed beyond its acceptable working range it can result in poor timing and/or intermittent loss of phase synchronisation, which typically produces a much noisier and less powerful motor due to the high speed "misfiring".
I used my original Magic Pie in sensorless mode for several weeks when I blew my hall sensors and found it to be slightly noisier than when it was running in sensor controlled mode, but it ran smoothly all the way to maximum speed once it had started running.
You may well find that the Turnigy motor will run smoother and faster with sensors fitted, but I suspect it could still suffer from misfiring at much higher rpm.
Alan
