I'm fairly new to the 170 CDI application, but so far I I've been using an 18.1x10 for break-in and after about 18 flights, have it leaned to 1 1/4 turns, using a little over 1/2 of a 16 oz tank for 1 trip through the Masters sequence. This is with a 50-50 mix of 30% and 15% Cool Power Heli fuel.

To power the CDI unit, I have a dual Tech-Aero regulator setup to the receiver with an 850 mAH pack for each, and then a Tech-Aero IBEC to run the CDI. I get 5 flights and still have about 40% capacity left in each battery. It's a JR 2.4 setup, dual elevator servos and so forth in a Prestige.