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A cold air intake (CAI) is an aftermarket assembly of parts used to bring relatively cool air into a car's internal-combustion engine. Most vehicles manufactured from the mid-1970s until the mid-1990s have thermostatic air intake systems that regulate the temperature of the air entering the engine's intake tract, providing warm air when the engine is cold and cold air when the engine is warm to maximize performance, efficiency, and fuel economy. With the advent of advanced emission controls and more advanced fuel injection methods modern vehicles do not have a thermostatic air intake system and the factory installed air intake draws unregulated cold air. Aftermarket cold air intake systems are marketed with claims of increased engine efficiency and performance. The putative principle behind a cold air intake is that cooler air has a higher density, thus containing more oxygen per volume unit than warmer air. ==Design features== Some strategies used in designing aftermarket cold air intakes are: *Reworking parts of the intake that create turbulence to reduce air resistance. *Providing a more direct route to the air intake by eliminating muffling devices. *Shortening the length of the intake. *Placing the intake duct so as to use the ram-air effect to give positive pressure at speed. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cold air intake」の詳細全文を読む スポンサード リンク
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