80 watts of power dont seem right to me. Is it 80watts of power per pound, or 80watts on your meter?
I have a 4120/14, and I have a 13x8 prop on it. I am using a 5s 6000mah Li-Po pack and I get:

true reading throttle settings:

1/4 throttle 20.6v - 2.7 amps - 57watts
1/2 throttle 17.8v - 18.1amps - 351watts
3/4 throttle 17.8v - 49amps - 891watts
full throttle 17.4v - 63amps - 1112watts