Aftermarket Air Filter - Shootout

  |   aftermarket Airfilters components Here are the aftermarket air filters we tested in this '04 1/2 Dodge Ram 2500 equipped with a manual transmission. Clockwise from the top left are: K&N, Volant, AFE, Airaid, True Flow, and S&B. Each of the intakes we installed provided a marginal horsepower upgrade over the stock setup that scored 309 hp at the rear wheels (see the chart). From our testing it appears that improving airflow alone to the turbocharger inlet on this particular Cummins engine will not instantly provide a boost in engine power. Why? In this case, we believe the engine needs more fuel to take advantage of the improved airflow. So is an aftermarket air intake a waste of your time and money? No. But depending on your truck and engine, it may need other engine modifications (injectors, performance calibration, or bigger turbo) to truly reach its potential. Ever spent a whole day installing seven air filters in a stock Dodge Ram and running the truck on a dyno? Well, now you don't have to. With help from the folks at Westech Performance, we tested a bone-stock '0411/42 Cummins with a stock air intake and filter and then compared the results to the leading intake systems available for this truck.   |   aftermarket Airfilters dyno Tuning Westech's Eugene Walde strapped the Ram to the dyno and performed the tests. He made multiple runs for each filter, and as an added touch, he used a zip tie to bind a shop rag to the exhaust catcher so its metal post wouldn't scratch the paint. Our results were shocking. We hoped for massive increases over the stock airbox and filter, and we thought this article would read like hate mail to the design team at Dodge, with criticisms about the ugly factory paper filter and seemingly restrictive intake setup full of bends and baffles. Boy, were we wrong. It turns out the engineers at Dodge did just what they were supposed to when they designed a system that is quiet, very effective at filtering dirt, and provides the maximum airflow that can be used by a stock Cummins 5.9L. Keep in mind the potential for more performance is possible with a modified truck, but all of these intakes eventually narrow down to the inlet size of the stock turbo. Since we learned it's not possible to significantly improve the horsepower over the stock setup (without the addition of a larger turbo, more fuel, bigger exhaust, and so on), we'll concentrate on how each setup sounds, what's included in the kits, the ease of installation, and how the intakes look when you pop the hood.   |   aftermarket Airfilters aftermarket Filter Dyno Results "Three-Oh-Nine, every time," became a running joke at Westech Performance on test day. Here is a dyno chart with the aftermarket filter results laid over the horsepower reading of the stock Dodge filter. Don't bother trying to tell them apart. The average results of the dyno runs ranged between 308.7 and 310.4 hp, and each filter had at least one run that was in the 309s. In fact, the stock air filter scored exactly 309.0 hp. Torque figures ranged from 566.1 lb-ft up to 573.0 lb-ft, which is not very different from the stock reading of 570.0 lb-ft.   |   aftermarket Airfilters stock Dodge Airbox The sealed stock Dodge airbox grabs air from inside the fenderwell, so you could say the Ram comes with a cold air intake from the factory. All of the aftermarket systems utilize this factory air inlet. The stock accordion-style tubing leads air through a sound baffling device before a 90-degree rubber elbow joint attaches to the turbo.

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AFE
The AFE intake tube and filter are by far the biggest of the group. Here is what it looks like without the top of the airbox installed. Even with the top bolted on, the AFE was the loudest intake in the group. It had a pronounced whoosh of air being sucked in and rumbling tones at low rpm that are not present with the other kits. It also has a very loud turbo whine above 2,000 rpm-which we liked.

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Eugene completed the installation of the airbox after he got sick of watching us struggle with the massive kit. The intake tube barely fits between the turbo and the engine oil filter and has an indent in the tubing to help the parts fit. Unlike some of the other kits, the AFE has metal tapped holes for easy reinstallation of the Intake Air Temperature Sensor. The diamond-plate airbox top doesn't completely seal the system, but it does provide protection from underhood heat. The openings also give onlookers a peek at the gigantic bright-blue air filter lurking under your hood. Unlike some of the other intakes in our test, the AFE completely replaces the stock setup. Airaid
The Airaid intake kit reuses the bottom half of the stock airbox and replaces the factory silencer with a Modular Intake Tube that the company says will increase flow by 20 percent. The installation was pretty easy because many stock parts were reused, but attaching the rubber heat shield that seals against the hood was a real pain. The kit also has a hole for mounting the stock air filter meter so you know when the Airaid element needs to be cleaned.

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When you open your truck's hood, parking-lot lurkers (like us) will immediately notice the oversized red filter that is exposed. The Modular Intake Tube is the black plastic piece between the accordion-like stock tubing. The Airaid was not very loud at idle or low rpm but really perks up around 2,000 rpm when you (and everyone else) can hear the turbo whistling. K&N
The K&N intake tube was very easy to install, thanks to the high-quality silicone boot that attaches to the turbo. The heat baffle drops right into the stock airbox location but has numerous mounting brackets, including one that requires you to remove a bolt from the alternator mount. Not a big deal, but it's more complicated than some of the other kits. The K&N is the only setup in the test group that includes a filter that snaps over the Intake Air Temperature Sensor. We're not sure how much it will help performance and/or reliability, but the chrome mini-filter sure looks cool. K&N also includes an opening for the stock filter meter.

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The K&N is a good-looking kit that is highly visible when your hood is popped. The intake tube curves over the top of the heat shield and dips the large element deep into the stock airbox location. The close proximity of the filter to the factory air inlet in the fender may be the reason the K&N is very audible at low rpm. It really wakes up above 2,000 rpm and is nearly as loud as the AFE. Other drivers on the road will definitely know you are approaching when they hear the high-pitched scream of your turbo. S&B
The S&B is a nice mix of function and style. It features a fully enclosed airbox, but the filter is visible because of a clear plexiglass top. For a personal touch, you can have it engraved for free when you order the intake online. We thought the S&B was the easiest installation in the group until we realized the pre-tapped holes for the Intake Air Temperature Sensor would not accept the stock screws without some help from a power drill-a minor inconvenience.

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The S&B uses one stock part, the turbo inlet tube with the white plastic baffles shown earlier in this article. When strapped into place, the airbox intake hole fits flush over the stock opening in the fender. This may be why the S&B is one of the only kits that allowed us to hear the turbo whine at low rpm. That turbo "noise" was quite loud above 2,000 rpm, and the high-pitched tones are really entertaining. Volant
The Volant box is another 100 percent aftermarket intake that straps directly to the turbo and uses a box with multiple inlets. One of those is designed for a ram air tube that sucks air from the fog light opening in the bumper of your Dodge. The others are a duct for the stock inlet and another opening on the front of the box. The kit uses a very stiff silicone boot that was difficult to attach to the turbo, but it probably won't slip off.

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Installing the Volant box will immediately give you a carbon fiber appearance under the hood of your Dodge. We liked the classy, understated look of the box and the silicone boots with the Volant logo. When the dyno wheel started spinning, we noticed a pronounced air sucking sound at all rpm-and we like that a lot. The turbo whine became noticeable above 2,000 rpm, but it was not as loud as the more open intakes. We wonder if installing the ram air scoop will increase the turbo sounds that escape from the truck. True Flow
The True Flow kit consists of a drop-in, high-flow oiled filter in the factory airbox and a hollow metal tube to replace the stock silencer, so it's a simple install. This is the stealthiest kit, and only a trained eye will notice the True Flow piece in the middle of the stock tubing. Most folks will think they are looking at a totally stock Cummins, which can be handy when you don't want folks to know about the diesel power you are packing. It's not hard to imagine the True Flow piece on the left will be less restrictive than the factory silencer on the right. Even with the sound-deadening piece removed, the True Flow was the quietest kit (other than the stock setup) that we tested. The turbo could be heard above 2,000 rpm, but was not noticeably louder than the factory intake system.

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