http://a123racing.com/
You can run an arc welder with these, no drop in voltage 2300 mah 6.6 volts The guys with big planes say you can run a 14 servo plane no problem, I've used them on my 50cc 7 servo plane no problems. A123racing.com have a full size electric motorcycle that does 8.20 at 155mph in the 1/4mile, you get a running start so you should do at least as well.
http://www.troybuiltmodels.com/Servo****ec.htm#HS7955
These will supply the power you need.