It’s safe to say that when it comes to cars, I’m a bit of an aftermarket upgrade nut. As a firm believer that improving on someone else’s design is one of the many joys of car ownership, I rarely find myself deviating from this mindset. Everything from the exhaust system and brakes to the aerodynamics are addressed when I purchase a car, and it all starts with a simple oil change and a quick assessment of whatever air filter was installed by the car’s previous owner.
Most of the time the filter gets a poor bill of health and is tossed in the trash while the oil is still draining, and in place of that decrepit old air filter I’m always sure to pop in one of K&N‘s reusable, million-mile warranty filters. This has become quite the familiar task to me, and over the years I’ve installed numerous K&N products on cars for my wife, my friends, my family, and myself.
So why am I so adamant about putting these expensive air filters on almost every vehicle I touch? What makes K&N filters so great, isn’t a filter from the dealer good enough? And do these filters really carry a million-mile warranty? I get hit with questions like these almost every month, and I assure all the skeptics out there that this is a legitimately well-designed product, and it won’t cause your engine to blow up or void any warranties.
There are those people who tell me they aren’t mechanically inclined and wouldn’t even know where to start. An official K&N install video for their car should prove to them that most K&N air filters can easily be outfitted in a matter of minutes using household tools, and that almost any competent mechanic can slap a complete air intake system onto a car in less than an hour. Also, let’s not forget that most auto parts stores stock a wide range of K&N products, and for web savvy shoppers out there (like myself), an inexpensive K&N air filter bought online before driving home a used car is always a smart decision.
Take a look at the Honda Fit air filter seen here on the left and compare it to the K&N air intake next to it. The stock filter looks more like a thick piece of toast with Lay’s potato chip waves, and its job is to keep contaminants out of the engine. But with its smooth aluminum bends, integrated heat shield, and much larger cone-shaped filter, there is little doubt that the K&N unit appears more capable. In an independent test conducted by MotoIQ, the Mitsubishi Evo X saw stellar results from a K&N intake, and everything from the intake’s power gains to the fit and finish received top ratings.
I always say that driving a car with a factory air intake system is like running a race while breathing through a straw. The straw will deliver oxygen, but only in restricted amounts, and it certainly isn’t going to make that 5K any easier. Cars are a lot like people in this regard: the easier they can breathe, the faster and more efficiently they can run, and a video by K&N illustrates the restrictions a stock filter will put on an engine. In the case of the Fit K&N saw a gain of 4.53 horsepower during dyno testing. While this may not seem like a lot, every pony counts –-especially when driving an under-powered car like the Fit.
As far as overall design and quality go, Edmunds agrees that it’s pretty tough to beat a K&N filter. With their washable high-flow cotton gauze design, these filters are both reusable and environmentally friendly, and are crafted to last the life of any engine. The four-to-six layers of cotton gauze media used are sandwiched between two sheets of epoxy-coated aluminum wire mesh, and the filter is also pleated and oiled to improve filtration. K&N filters are also legal in all 50 states, so there’s zero risk of voiding warranties or failing inspection.
So the product gets great customer reviews and real world independent tests like the one done by Hot Rod Network back up the company’s claims. But why are these filters so damn so expensive? Simply put, a K&N unit costs a lot more than a basic paper drop-in filter because all that designing, engineering, manufacturing, and testing really does add up. However, mechanics agree that cheap air filters can end up costing a driver more in the long run by hurting fuel economy due to poor air flow, allowing contaminants into the engine, and requiring replacement every 12,000 miles instead of every 1 million miles. So unless that car is going up for sale anytime soon, it’s probably best to at least upgrade to a basic K&N drop-in unit.
My relationship with K&N started about a decade ago when a friend of mine who built race cars told me that I was a fool for not putting a K&N drop-in filter in my car. I’d seen the advertisements on TV boasting “how this amazing filter could save me gas, save me money, save the environment, give me more power, etc., etc.” I’d never taken the ads seriously, thinking it was just another company riding the coattails of The Fast & Furious-inspired performance car craze, but after looking into it, I found out that K&N had been around since the 1960s, and had a reputation among race teams, including NASCAR drivers. So with a remaining hint of reluctance I shelled out $50 for an air filter, went for a drive, and never looked back.
Flash forward 10 years (and several car upgrades later) and I’ve seen it all when it comes to K&N filters. It’s thrilling to see my RPM’s drop 1,000 fold when climbing a hill on the daily commute, to revel in the snappy throttle response felt in K&N equipped cars, and to perform the simple air filter cleaning procedures to keep my investment functioning properly. Other than making the rookie mistake of not rinsing and re-oiling my filter the night before a big road-trip and getting mediocre mileage all the way to the beach, I’ve had zero issues with any of their products – and I revel in the fact that I’ll never have to throw another dirty air filter in the trash again.
It’s also important to know that there are no guarantees in this world when it comes to fuel economy, and it’s highly unlikely that someone is going to suddenly see amazing gains after they install a K&N filter. There might be an extra mile per gallon gain, but poor fuel consumption is better combated by having properly inflated tires, addressing poor driving habits, avoiding steep terrain, and keeping up with maintenance on engines with high mileage. A report by Autoblog shows that long-term car owners will also see the greatest benefits “with a K&N [filter] providing a savings of about $285 over 250,000 miles.” Savings are increased when upgrading to an intake system courtesy of a larger cone filter and smooth mandrel-bent aluminum piping.
One of the most interesting things to me about K&N is that they keep looking for ways to improve efficiency in every category imaginable. In recent years K&N has branched out into manufacturing its own line of oil filters, cabin air filters, fuel filters, and have even come out with a washable oil filter that has magnets inside to collect metallic debris. And whoever came up with the idea of attaching a 1-inch hex nut to the end of an oil filter should get an award because a stuck oil filter is a terrible thing to encounter during any oil change. So what’s next for the world’s largest air filter manufacturer? Personally, I’m waiting to see if it comes out with reusable high-flow furnace filters and water filtration systems for my house.
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