How to calculate overunity

[dakanadaka]

I have electromotor that spins the disc with magnets south north south north and copper gives the heat as the reaction of spinning disc with magnets.

so here is example:
I have copper box and that copper box contains 20 liter of oil (s2 shell heat transfer) then I start electromotor and temperature rise like this:
start temperature of water is 22 and motor start to spin 00:00:00 I run motor at 5.6 AMps with elektromotor of 4kW. After 17 minutes temperature goes to 95Celsius and kw meter shows that it used 0.8 kW.
Im trying to calculate what is the efficiency and to find formule of input energy and in my case it is 0.8kW and output I dont know how to calculate so I can see if Im close to overunity or not.
tnx