RE: motor limit?
One of the most common mistakes about getting started in electrics is that kids today shoot right for the motor with the fewest turns possible. Myself, I prefer running the extremely close races in the stock class, but some like to be in the mods rebuilding motors after about 5-10 runs.
The fewer the turns, the hotter the motor will run, and the shorter run time you will have too. This is where picking a battery pack comes in. If you want to do modified racing, lets say 16 turns on down, its recommended that you use a NiMH battery pack. The reason is that they discharge slower compared to a Nicd battery pack. The slower the battery discharges, the longer the run time you have. Thats what makes it perfect for modified racing. Now, in the stock class, a Nicd is highly recommended because they discharge faster. Since these batteries discharge faster, that means more punch and power going right to your motor. Also, since its a stocker, it wont hurt you in run time compared to running a 2400 nicd battery powering a hungry 14t motor. Running a NiMH in a stocker might get you longer run times, but it is noticeable on how much slower the car/truck feels.