Rule of thumb to remember: Lean is fast, Fat is safe. This holds true for all, but us nitrous guys take it to heart. Like mentioned before, you want it to run as lean as you can, but without detonation. All an internal combustion engine is, is a big air pump. Get the air in, and get it out as fast and efficiently as possible. The fuel makes the air mixture explosive, and that's what drives your air pump. Extra fuel in there takes up space that we could put more air in, and actually takes longer to burn. Once the flame front starts across your combustion chamber, too much fuel means it's still burning even after your piston is long gone. Then we have too many spent gasses to get rid of on the next stroke as well. There's A LOT more to it than that, but in a nutshell more fuel WILL NOT make more power, unless you add more air to go along with it.
