Nearly all factory air intakes are designed with some sound baffling, and this sound baffling is the primary reason that aftermarket air intakes all manage to improve performance to some degree. You can have free, unrestricted air flow, or you can have quiet air flow…but you can’t have both. However, no amount of clever engineering can make up for the following fact: To their credit, engineers at these automakers do a great job of building air intakes that hit all these notes. design an air intake, they’re primarily focused on building something that’s cost effective, quiet, and efficient. Why Almost All Factory Intakes Are Restrictive 500CFM of air flowing into your engine makes noise.Higher temperatures mean lower densities. The density of air varies with temperature.If you can imagine taking 40 deep breaths in one second, than you can understand just how much air a 5.0L V8 is sucking up at wide open throttle.įor the purposes of determining if cold air intakes actually work, we need to remember two things about all this air coming into your engine: To put 500 CFM in terms we can understand, human lung capacity is about 0.2 cubic feet. A 5.0L V8 operating at relatively high volumetric efficiency (85%) will require as much as 500 cubic feet of air per minute (500 cubic feet per minute, or CFM) at wide open throttle. Basic chemistry tells us that an engine needs about 14 times as much air as fuel – at least when you’re comparing a unit mass of gasoline (with MTBE) to a unit mass of air.Ĭhemistry aside, this means that your engine needs a LOT of air. Let’s Start With the Factory IntakeĪn internal combustion engine is basically a pump – you put air and fuel in one end, and you get exhaust gases, heat, and a spinning crankshaft at the other. Here’s the deal: there’s a definitive answer to the question “Do cold air intake kits really work?” Once you understand the engineering and science behind air intakes, you’ll know the answer as well as anyone (and you’ll be able to explain why, too). Do aftermarket air intakes – like the K&N Air Intake Kit shown above – actually increase horsepower? Some will argue that factory air intakes are restrictive, some will say that factory air boxes suck up a lot of heat from the engine compartment, and others will say that automakers would have already installed these parts if they worked as well as companies like K&N say they do. Want to get a debate going at your local car meetup? Ask people if they believe cold air intakes actually “work.” If your local car get togethers are anything like mine, you’ll get a lot of interesting opinions and contradictory facts.