Actually the 4600 and Sidewinder is rated for 12 cells! If you gear it right it would last and stay cool, and it would haul *****.
CMS-4600 Motor-
Input Voltage: 12 cell NiCd/NiMH Max, 3S LiPo Max
Size 1.4" (35mm) dia. x 1.7" (43mm) length
Weight: 7oz (198.4g) with wires
Shaft Diameter: 1/8" (3.2mm)
Bearings: Oversize ABEC-1 front and rear
Connectors: 4mm gold
http://www3.towerhobbies.com/cgi-bin...&I=LXUTA1&P=ML