Ok so testing the motor has shown some good things and some bad things.
First the good things.
This motor has so much torque it is incredible, I don’t doubt that I will be able to get the top speed and acceleration that I want from this little 5.5Kg motor. Mounting the motor should be simple and water cooling ports are simple to implement and use.
Ok now the bad.
This is not a specific problem with this motor but in general with Outrunner motors. When you fit sensors in the motor to enable smooth high torque at startup and low revs then there is an issue at higher revs. The hall sensor/controller/power circuit/flux buildup time becomes significant. Due to the number of magnets and the high rotation speed the small lag that is 0 degrees at standstill the The lag at 2000rpm is about 15 degrees and at 5500 rpm it is about 35 degrees and starting to try and drove the motor backwards.
What we need is a variable timing advance tool that will dynamically adjust the signals from the sensors to account for the lag. Thankfully someone is already working on one of these devices.