X2 on Carl's comment. You might try the impact wrench before heating the nut if you're concerned about the crank.....although as long as you keep the heat contained you should be okay. Most time, the sudden jarring of an impact will accomplish what brute strength alone cannot. If you don't have a good impact (air or electric) pick one up as it will save you a lot of headaches later on. Also, don't make the mistake I did in my younger years........buy good quality, name brand impact sockets. Even if you don't think you will use them much, the cheaper ones are made with cheaper steel and will strip out quickly.
Good luck!
