Best power mixture

The fuel-air mixture ratio used in a reciprocating engine that allows the engine to develop its greatest amount of power. The best-power fuel-air mixture ratio, which is in the range of 0.074 to 0.087 (13.5:1 to 11.5:1 air-fuel ratio), is richer than the ratio used for the best economy. The additional fuel in this mixture is used to remove some of the heat from the cylinders when the engine is producing its best power.