Aftermarket air intake systems are one of the most popular engine modifications available for late model cars and trucks. But why are they so popular? Didn't the manufacturer equip your car with the best parts available? Well, it depends on your point of view, whether you're a car buff or only care about the cup holders. Because you're reading this we assume you're in the former category, so read on for answers. We'll explain what these systems do for your ride and why you need one.
You may have heard the internal combustion engine described as nothing more than an air pump, and to a certain extent this is true. Air, containing mostly oxygen and nitrogen, is pumped into your engine's cylinders along with fuel during the Intake stroke, compressed and burned during the Compression and Power strokes respectively, and then the spent exhaust gases are forced out by the pistons during the Exhaust stroke. Any resistance to the free flow of gases during the intake or exhaust stroke robs power from your engine, which is why aftermarket air intake systems, exhaust headers and less restrictive exhaust systems are common engine modifications. By reducing restriction, an aftermarket air intake system not only reduces pumping losses, it enables your engine to take in much more air. We'll explain how this additional air benefits your engine momentarily, but for now let's talk about restriction and how aftermarket systems eliminate it.
The factory air intake system on your car or truck is restrictive because it's a compromise. It's not that the engineers that designed your car or truck don't know what they're doing, but they had to take factors other than performance into account when they designed the air intake system, like noise and ease of maintenance. Sadly, most people that buy cars, even performance models, are perfectly happy to leave them as they are. And the additional air intake noise when the pedal is mashed would be the source of a complaint, not sweet music as it is to an enthusiast!
The flat panel air filter used on most late model vehicles may be easy to replace, but its small size makes it the primary source of restriction. Most aftermarket air intake systems start with a large, conical air filter installed in place of the factory filter and its airbox. While every manufacturer makes claims about the effectiveness of their filter media, the one thing all these aftermarket filters have in common is much more filter surface area, for much less restriction.
The next source of restriction is the factory air intake tube. Most factory tubes make awkward bends and have sound baffles, which may inhibit noise but also restrict airflow. Aftermarket air intake tubes are usually constructed from mandrel-bent aluminum or molded polyethylene. While polyethylene has a slight advantage in that it can be molded asymmetrically, both types feature larger diameters and smoother bends than the stock, factory unit, for less restriction and greater airflow all the way to the throttle body or turbocharger.
Types of Air Intake Systems
There are 3 basic types of aftermarket air intake systems. The simplest system is as we've already described. It takes the place of the factory air filter, airbox and air intake tube, substituting a large, free-flowing, conical air filter and smooth, free-flowing mandrel-bent aluminum or molded polyethylene intake tube. Some systems feature an adapter that smoothes the flow of air from the filter to the intake tube. This system fits entirely within the engine compartment and is sometimes referred to as a "Short Ram" system.
The 2nd type of system is the cold air intake systems. As we'll explain in more detail shortly, cold air is denser and better for combustion, but cold air here can best be described as air that is cooler than the air under the hood. To enable the air filter to take in cooler air, some manufacturers employ air dams that seal against the hood and shield the air filter from engine heat, while others use their own proprietary airbox, with air inlets positioned to only take in cooler air. The most dedicated systems position the air filter outside the engine bay, usually behind the bumper. Because these systems make the filter vulnerable to water during extremely wet weather, the intake tube sometimes comes in 2 pieces, so the system can be converted to a "Short Ram" when desired.
The final system type is a variant of the cold air intake system, with the addition of a "scoop" to force air into the filter. These "Ram Air" systems position the scoop to take advantage of high pressure areas in front of the vehicle, to force cold air into the air intake system.
The Benefits of Greater Airflow and Cold Air
Increased airflow allows your engine to burn more fuel, and more fuel equals more power. An engine operates most efficiently with a mixture of 14 parts air to one part fuel, also known as the stoichiometric air/fuel ratio. So, if more air is supplied to the engine, more fuel can also be burned. More air and fuel (in the proper ratio) in the combustion process means a more forceful explosion driving the pistons, resulting in more power to the wheels.
Cold air is denser and contains more oxygen. It's the oxygen in the air that combines with the fuel for combustion, so if the increased airflow is also cooler, more fuel can be burned resulting in even more powerful combustion. It's estimated that for every 10 degrees cooler the air intake charge, power will increase by 1 percent.
Thankfully, the electronic fuel injection systems on the late model vehicles that these systems are designed for, especially those with MAF (Mass Air Flow) sensors, have no trouble compensating for the increased airflow. The Engine Control computer reacts to the increased airflow by increasing fuel delivery to maintain the correct air/fuel mixture.
Modern vehicles are electronic marvels, with variable valve timing and other complexities that make traditional hotrodding mods like cam replacement impossible or beyond the scope of the average enthusiast. Their high level of tune from the factory also makes them hard to improve upon. This makes the aftermarket air intake system the best investment for your performance dollar. The manufacturers we represent have verifiable performance claims backed up by dyno testing. One of these systems will increase your engine's horsepower and torque, with improved performance you can feel in the seat of your pants. And, if you can restrain yourself, you might even see a few more miles per gallon! An aftermarket air intake system is simply, the biggest bang for your buck.
by Justin Gazzara on