http://brantuas.com/ezcalc/dma.asp is a link for a free motor calculator that may help you make some decisions. My wild guess would be a speed 400 geared 4:1 on 7-8 cells turning a9x6 or 10x6 prop. I'm sure one of the electric gurus will chime in here! How's the kit quality? I order a bunch of stuff from balsa products, have been very pleased so far.