Depends how you are gear my friend. My 1512/3D draws up to 75 amps geared for 45mph, on 7s A123 pack. MY Revo is now just over 9 pounds, very light, and accelerates like mad.
So if you can guess on your weight, and speed, then I can guess on amperage, I have taken a few eagletree's on my setup, and have enough experience that I should be close.