How Air Filters Work

There’s more than meets the eye in High-Performance Air Filters. Airaid explains what goes into designing a High-Flow Air Intake System.

Stephen Kim Oct 22, 2013 0 Comment(s)
View Full Gallery

Build it Yourself

Swapping late-model EFI motors like Gen III/IV small-blocks into older muscle cars is very popular, but it often requires building a custom air intake system. Depending on your fabrication chops, this is a task that’s either stupid easily or extremely intimidating. Fortunately, Airaid’s U-Build-It (UBI) intake kit makes the process simple for hot rodders of all experience levels. “Our UBI kits include a long piece of molded plastic tubing that features multiple 30-, 45-, 60-, and 90-degree bends in addition to several straight sections of tubing. All you have to do is cut the tubing to arrange the bends and straight sections into a shape that fits inside your car’s engine compartment,” McGee explains. “The kit includes couplers, clamps, brackets, hardware, and a conical air filter to help build a custom intake into any shape you desire. There may be a little head-scratching involved when first laying out your design, but the UBI kit is very user-friendly and the only limitation is your imagination. The exciting news for F-body and A-body owners is that we’ve recently come out with cold air panels that snap into the stock radiator core support. These panels isolate the filter from engine heat to further enhance performance.”

Tubing Dimensions 2/14

Filter Cleaning

In addition to increased airflow, one of the great perks of an aftermarket cotton gauze filter is that they can be cleaned and reused. Airaid recommends cleaning SynthaMax filters every 20,000, and SynthaFlow filters every 30,000 miles. While servicing a filter is easy, there are some very specific steps that must be followed for optimal results. “After removing the filter, gently shake or brush off excess dirt and debris. Next, spray Airaid cleaning solution onto the filter and let it soak for 10 minutes,” McGee says. “Rinse the filter from the inside out with a hose set at low pressure until the water turns clean, then let the filter air dry. Once the filter is completely dry, apply a light coat of Airaid performance oil until the filter is uniformly pink. After it’s dry, the filter is ready for reuse. Airaid offers filter tune-up kits that include the cleaning solution and performance oil.”

Airaid Tune Up Kit 3/14


Cleaning an air filter is straightforward enough, but McGee warns against over oiling the filter. “If too much oil is applied to the filter, it can enter the air stream and land on the MAF sensor. The way MAF sensors meter air is by sending voltage to a heated filament, then determining airflow based on how much the temperature across the filament changes,” McGee explains. “When oil gets on the MAF sensor, the heating and cooling characteristics of the filament changes, which causes it to read incorrectly. This can lead to an overly lean or rich air/fuel ratio. Some MAF sensors can be salvaged with TB cleaner, but sometimes they have to be replaced. Consequently, you should always take the necessary care to avoid over-oiling the filter.”

“In situations where oil has gotten onto the MAF sensor, it’s almost always due to a filter that’s been over-oiled during servicing.” —Trent McGee

Dry Filters

Airaid’s standard SynthaFlow filters are built from several layers of cotton gauze in addition to a synthetic layer that prevents the filter oil from entering the airstream. Although servicing the filter is a straightforward affair, Airaid has further refined the design to make it even more user-friendly. “In 2009, we introduced the SynthaMax filter that features a 100 percent synthetic filter material. It has the same airflow benefits as our SynthaFlow filter, but does not use any oil,” McGee says. “This prevents the potential of over-oiling the filter during servicing. Furthermore, SynthaMax filters can be washed out with a regular household detergent. They don’t require the use of a special cleaning kit. While SynthaFlow filters have a proven track record, SynthaMax filters are a great option for those who don’t want to oil their filters.”

Heat Isolation

Engines prefer ingesting cool air over hot air, so reducing the inlet air temperature is always a top priority when designing an aftermarket air intake system. “Colder air is denser air, and denser air packs more oxygen molecules, which makes more horsepower. If we can relocate the air filter to a cooler spot under the hood, we will incorporate that into our design,” McGee explains. Taking this concept one step further, some of Airaid’s air intake kits include a cold air dam that isolates the filter from underhood heat. “Our cold air dams replace the stock air box entirely or snap into the bottom of the airbox. Sometimes you want to retain the bottom portion of the stock airbox because it has inlets routed to cooler ambient air. Another nice feature of our cold air dams is that they have weatherstripping on the edge of the panels. The weatherstripping seals off the filter by turning the hood into a lid that blocks out heat.”

Airaid Intake Tube 4/14
Airaid Intake Tube Jr 5/14

Product Lineup

Airaid’s diverse range of products encompasses applications for fifth-gen Camaros, C6 Corvettes, S10s, and just about every Gen III– and Gen IV–powered truck Chevy has ever built. For older vehicles with TBI induction systems, Airaid’s Classic system features a filter adapter that bolts in place of the factory round air cleaner. Attached to it is a powdercoated intake tube that utilizes a conical air filter. “This arrangement allows us to move the filter from on top of the engine to a cooler location under the hood. The next step up is our CAD intake systems that feature a cold air dam, a molded intake tube, and a conical air filter,” McGee explains. “Airaid’s MXP Series intakes are our top-of-the-line models that include a conical filter, a roto-molded high-flow airbox, and a high-density polyethylene intake tube designed to maintain proper MAF sensor readings. Some MXP systems also include a velocity stack that further improves airflow and velocity.”

Budget Options

Since different enthusiasts have different budgets, Airaid offers a variety of entry-level air intake options that can be upgraded later on down the road. “Our junior intake systems replace the most restrictive parts of a factory intake system: the paper air filter and intake tube. These kits include a drop-in stock replacement panel filter, and an Airaid modular intake tube for an economical yet effective solution to boosting airflow,” McGee says. “The modular intake tubes are also available separately, and can be attached to a stock airbox. That way you can install a modular intake tube, and upgrade to a conical air filter at a future time. Some cars have very well-designed intake tubes from the factory. If that’s the case, we won’t bother designing our own tube because if there’s no gain to be had, we don’t want to sell people parts they don’t need.”

Carb Filters

Although Airaid’s air intake kits are geared primarily for the EFI market, the company hasn’t neglected the jet-and-booster crowd. “Airaid offers a full line of replacement filters that drop right into a carbureted air cleaner. We also have carb hats that can be used with our UBI kits,” McGee says. This arrangement is great for cars that have limited hood clearance, and it allows relocating the filter to a cooler location under the hood. If you prefer a more traditional look, Airaid’s Classic II air cleaner assembly is an exciting new alternative. It features a tapered 14-inch diameter filter available in 3-, 4-, and 5-inch heights. “The housing is built from hand-poured urethane for durability, and the assembly is topped off with an aluminum lid for good looks. Other features include a drop based for maximum hood clearance, and a contoured lid that enhances airflow and provides additional clearance for the carb vents.”

Airaid Carburetor Hat 200 100 9/14


Phoenix, AZ 85050




Connect With Us

Get Latest News and Articles. Newsletter Sign Up

subscribe to the magazine

get digital get print