Videogames like Need for Speed and Gran Turismo, and movies like The Fast and the Furious and Tokyo Drift are introducing many people to the world of car customizing. One of the most drooled-over upgrades is a simple air-intake upgrade that consists of a new intake tube that is streamlined and replaces your old hose, and a cylindrical filter. An air-intake is designed to provide a less restrictive airflow, colder air, which contains more oxygen than warm air, thus increasing horsepower, improved fuel mileage, and a low-pitched noise. Is it really worth $100 to $350 for one of these?
Simple answer: the more upgrades on you car, the more power it adds. Say you have a completely stock (no factory installed parts have been changed) Honda Civic. You decide to put an air-intake on the engine. Some manufacturers say that an air intake on a Honda Civic can add up to 20 horsepower. A stock engine without any other upgrades like a turbo-charger or high-rise throttle-body does not need as much air as an engine with all those upgrades, so you will be lucky if you get an increase of 10 horsepower—and that’s 10 horsepower to the engine, which translates to about 5 extra horsepower at your wheels. It’s not easy for anyone besides a race-car driver to tell the difference 5 horsepower makes. On the other hand, if you’re running a V8 IROC Camaro with a supercharger, nitrous system, high-flow injectors, and a stock air-filter set-up, you’re pretty much making your car get air through a straw, thus losing horsepower. And fuel mileage: how does an intake improve it? Well, if your car has more horsepower, you don’t need to step on the gas pedal as much, thus saving gas. If you can’t even feel your horsepower gain, you won’t notice a difference at the fuel pump.
Say it’s the sound you’re after, but you’re unwilling to spend any money on a custom exhaust system. Take off your air filter silencer(s). Many cars that have to be smog checked have an air filter silencer, or silencers installed. Basically, just remove any boxes and/or tubes that come before the opening hole on your stock air-filter box, and you’ll get a low-pitched sound just like an air-intake would provide, and an extra horsepower.
Basically, if you’re building a racecar and you’re after every 1/10 of a horsepower, it’s worth getting a custom air-intake. However, unless money’s burning a hole in your pocket, a custom air-intake will not provide a noticeable power difference on everyday cars.