This 2nd example uses the turnigy SK 6364-230kv motor.
http://www.hobbyking.com/hobbyking/s..._230Kv_/_3150W
its the same motor Im running with an 18x12 prop. The specs say it can turn a 22x12 or 24x10. Thats too much prop for this motor and will blow a magnet as some ppl have stated in the reviews of it. If you keep the prop size to 18" diameter or below, even with a high pitch, you'll be fine.
For an 8s setup, you could use an 18x12 prop or a 15.75x13 3 blade.
Comparison same motor static full throttle:
10s on 18x12 = 104mph
8s on 18x12 = 83mph....still very respectable

10s on 15.75x13x3 = 113mph
8s on 15.75x13x3 = 90mph
Note: a 3 blade will act similarly to a larger diameter lower pitch 2 blade...so effectively a 17x12 2 blade.
Since the dimater is smaller then the 18x12 in the first set, your likely to get a little more rpms thus the numbers are still pretty close to accurate....this assume the prop is loading the motor up enough tog et to peak power.
On my SK 6364-230, the 18x12 is giving me about 2500 watts on 10s even though the motor is rated for 3200 watts. 2500 is more then enough, so even on 8s, you'd be over scale speed.