When selecting an electric power system ( Motor, ESC and battery) everything is based on total watts and watts per pound required. Total watts is figured by multiplying the battery input voltage x the motor draw in amps. The amp draw of the motor, greatly depends on the prop. selection, but you can at least ballpark when trying to select a power system based on the continuous and max. burst amp ratings provided by the manufacturer. Then you can simply prop. up or prop. down depending on testing, and what you actually need. The battery selection depends on how many volts are required, when multiplied by these amp ratings, to get you to the total watt number that will provide the proper performance level for your aircraft. You can pretty much select the motor, then couple it with the proper battery, and then just select an ESC last that matches the two in terms of specifications.

Here are some general guidelines for total watts:

70-90 watts per pound of aircraft - TRAINER/SCALE FLYING - 90-110 watts per pound of aircraft - SPORT/MILD AEROBATIC FLYING

110-130 watts per pound of aircraft - ADVANCED SPORT/AEROBATIC FLYING - 130-150 watts per pound of aircraft - EXTREME AEROBATIC/MILD 3D FLYING

150+ watts per pound of aircraft - ADVANCED/UNLIMITED 3D FLYING


So for an example - Let's say we have a 17oz plane (your case) that we want to pick a system for. Take the 17oz, divide by 16 to get pounds = 1.0625 pounds.
Now take the 1.0625 pounds and multiply by 150watts for Unlimited 3D Performance = 160 total watts minimum required for this model to acheive Unlimited 3D Performance.
So now you are looking for a motor that can at bare minimum deliver 160 total watts. For the battery, say as in your case, you want to use an 11.1volt 3cell, take the 160 total watt number and divide by 11.1volts to figure out how many amps would be required of the motor/prop., when paired with an 11.1volt LiPo = 14.4amps. So now you know that when using an 11.1volt LiPo, you need a motor that can handle 14.4 amps on a continuous basis, handle 11.1volts and be capable of 160 total watts. As for the ESC selection, you always want a good cushion in there so things run cool and nothing really gets stressed. Basically, you look at the max. burst rating for the motor in terms of amps, and add in some cushion. With this example, something equivalent to the Park 450 or Torque 20T-1030 in terms of specs. would do the trick. With a max. burst rating of around 18amps, a good bet for an ESC would be a 25 amp, that can handle a 3cell LiPo.

Hopefully this helps some