A cold air intake is designed to direct cooler air into the engine as opposed to preheated air that is a consequence of engine heat in the vicinity of the air cleaner. The colder the air, the denser the charge, which equates to higher horsepower. This has been known for a long time to the auto racing crowd. Some racers will go to such extremes as running the metal fuel line in a coil just ahead of the carburetor, placing it in a coffee can size cooler. They fill this container with dry ice to super chill the fuel. There are different ways of cooling the air prior to its induction into the engine.
There are only a few rules to remember. Do not run an intake tube low to the road, since rain or water on the road could be sucked into the intake and the engine. Water, unlike air and fuel, is not compressible. Water introduced into the engine in anything but a fine vapor can cause an engine to break or bend a rod. Make sure that there are no restrictions such as too small a tube to flow the proper CFM or too many bends. On a fuel-injected engine, make sure that it fits the mass air flow sensor tightly so that there are no leaks and that the intake air temperature sensor can be used.
The tube should be made of plastic or rubber, or of a material that does not absorb or conduct heat readily. The fancy chrome cold air intakes sold at many parts stores are an oxymoron--installing a metal tube in place of a plastic one will not work. The metal tube conducts heat rapidly, and does the opposite--heating the air making it thinner before it hits the intake. The only way the metal air intake tubes will work is if you wrap them in asbestos tape to isolate the tube from the heat. The best place to install the front of the intake is behind the headlight or in the right side fenderwell where there are openings between the inner fenderwell and the fender.
