A cool air intake provides some primary advantages and disadvantages to any engine dependent upon the function and performance desired. The decision becomes simple when a few factors are considered.
Cool air contains more oxygen than warm air. It actually is oxygen, not air, that your engine needs to burn fuel efficiently. The more oxygen available, the more efficient your engine can be. The key is actually how your engine captures that cool air.
In cooler climates air can be too cold. The frigid air does not get the opportunity to warm before entering the combustion process, so it actually slows the burn of the fuel. Warmer air actually allows the fuel to burn more quickly, thus maintaining engine timing.
For everyday use, the answer is found in balance. Usually a cold air intake with an air box provides an adequate solution. The air entering is cooler, and the air box gives air that is too cool a chance to warm slightly before entering the motor. However, for racing applications a straight cold air intake may work just as well, and in areas of extremely low temperatures, such as Alaska, a warm air intake works best.
