I also run the 6800 in the rc18...... It runs pretty hot though, and I cannot find a gear low enough. I want to step up to 3s soon, but with the high temps I am getting on 6c, I don't want to even push it. I did however hear great things about this motor. It is 4200KV, with a built in heat sink, and from what I hear, people cannot get it to overheat....

http://www.hobbycity.com/hobbycity/s...idProduct=4215