Important Facts About Automobile Air Filters

Having a new air filter in your vehicle is a part of maintenance that many car owners might not even know they need. Knowing the proper facts about air filters will help ensure that you’re educated when purchasing or getting the next air filter installed on your vehicle. What does an air filter do? If you’ve ever been for an oil change or any type of standard vehicle maintenance, the service technician might have told you after that you need a new air filter. An air filter is basically there to clean the air before it has a chance to get to the engine. With all sorts of different air filters on the market, it can sometimes become frustrating and tedious to know what to look for when seeking one. When there are restrictions throughout the air induction system, it can cause an engine’s power output to substantially decrease. This is why many competition vehicles don’t come with air filters.

When the air has to pass through a filter element, flow can sometimes become problematic. The standard paper elements are a lot of the time, resistant to airflow. This is because the material that the filter is made of is usually fairly dense. When there is more restriction to airflow, then there is a larger loss of power. Over the years, K&N engineers have made several improvements in the overall durability and performance by paying attention to the compromises involved. At the beginning of the 1960s, K&N created a filter element that exceeded the filtration standards, while at the same time, caused barely any restriction to airflow. The first K&N air filter was created by pressing together many different layers of surgical gauze inside two sheets of wire mesh. To lower the filter’s size, the medium was pleated. After that, the gauze was oiled so that the filtering capabilities were better.

In the world today, this same overall concept is still used as the method for all industrial, marine, automotive, and motorcycle air filters. Even though K&M’s cotton-gauze filter process can get expensive, it is truly worth the extra work involved. Compared to a standard paper filter, the K&N filter will flow 50 percent more air without decreasing the efficiency of filtration.

Air Filter Comparison

There are several differences between paper air filters and K&N ones. Paper filters are produced from compressed fibers. Between these fibers are extremely tiny holes that air needs to pass through. Over time, these holes get clogged with dust, debris, and dirt. When a hole gets completely plugged, air will look for a different way to pass through it. Once more and more of these microscopic holes begin to get clogged up, there is a build-up of excess resistance which results in lowered horsepower in the vehicle and a decreased fuel economy.

There are certain standards that air filters require:

  • The material of the filter must be thick
  • The fibers need to be very dense

By design, paper-based filters are restrictive to airflow. If you compare paper filters to K&N filters, you can quickly see that they aren’t safe for filtration. Once a paper filter becomes clogged up over time, the pressure in the filter will decrease. At the same time, the air pressure outside of the filter will stay at the same level. An example of this can be thought of as when you are trying to suck the air out of a pop bottle or milk bottle. The bottle will succumb to the pressure and collapse when the pressure becomes too high.

When there is a high-pressure differential created by a filter that is restricted, it can actually start to pull dirt and dust through the paper. A paper filter will lose its ability to filter the air and protect your vehicle’s engine once its life starts to expire.

Paper Air Filter At A Glance

  • Consists of pleated wood pulp that is meshed together.
  • The filter must be replaced around every 10,000 miles due to a build-up of dirt and debris.
  • The filtered air is turbulent.

Foam Air Filter At A Glance

  • Foam is typically saturated with oil.
  • Dust, debris, and dirt can build up on the exterior and block openings.
  • Pressure can distort the foam cells which might allow dirt to enter deeper inside the filter.
  • As the foam cells start to get blocked with dirt, airflow will be reduced.
  • The filtered air is turbulent.

K&N Air Filter Specifics

In comparison to a standard paper air filter, the K&N filter is a little more in-depth. Because the cotton fabric in these air filters is oiled, they can hold airborne dust particles. The particles will seal up against the exterior of the filter and become part of it. The cotton fabric is placed between an aluminum screen that is pleated. The goal of the pleated surface is to increase the overall surface area, and this allows more airflow and a longer time between having to get it serviced. In comparison to a standard foam, pleating exposes around five times the surface area.

As soon as dust and dirt start to build upon the K&N element, they have little impact on how well air will flow through it. This is mainly because there are no holes that can be clogged on it. The criss-cross patterns of the cotton fibers are held in place by the oil, and particles have a very difficult time breaking through this barrier. Once the filter starts to gather dust and dirt, this, in a way, forms its own type of barrier that makes it even more difficult for further dust and debris from getting past the surface. As dust particles collect on the surface, the efficiency of the filter increases, and this is something that drastically extends the life of the filter. Even after 50,000 miles of use on the street K&N filters, they will still have around 60 percent of the maximum airflow capacity available.

If you compare that to a paper filter, dust and dirt building up on the fibers will restrict airflow at a magnified rate. The overall performance of paper filters decreases at an alarming rate once they begin to get dirty. At around 14,000 miles of use, the air that can flow through the paper filter decreases at a rate of up to 70 percent. This factor alone makes the K&N oiled cotton gauze filter leagues ahead of the paper filter. If you’re the type of person that wants to gauge how well your filter is doing, you can use what is called a vacuum gauge. As a filter starts nearing its expiration, the vacuum reading will start to increase. If you have a high vacuum reading, then that means that the filter should be serviced.

There are many different types of trucks on the road that have logged well over 100,000 miles and have reported no loss in the airflow by technicians servicing them. The performance of a K&N filter is something that proves itself time and time again. You simply get better airflow for a longer period of time.

What About Stock Replacement Filters?

For the consumer that is focused on consistent service, the stock air filtration system is the easiest way to figure out the exact type of replacement filter that is needed for a vehicle. There are minimum acceptable dimensions that are listed for each part, and this is what ensures that they will fit perfectly in the stock airbox. The methodology and material that is used on the filters are so trusted that they are warranted up to a staggering one million miles or ten years. K&N filters are also legal on the emissions side of things in all of the United States.

When it comes to street engines, they face many of the same risks that racing engines do, but just for a longer duration of time. Because of that, an air filtration system needs to be very durable so that the vehicle can be relied upon in all of the different driving conditions. If consumers want to kick things up a notch in terms of vehicle servicing, they can also get a K&N filter charger installed in place of the original. Doing this will give the engine the ability to take in all of the air that it possibly can. When an engine can take in all of the available air, the performance of it is increased because oxygen is needed for combustion.

The computer inside a fuel-injected car will add just the proportionate amount of fuel to make up for the air, but if it’s a carbureted engine, then no further adjustments typically need to be made. For those that are into competitive motorsports, sometimes a re-calibration will need to be done for the best performance.

The gain in performance will be recognizable to some, but a four-cylinder vehicle might only notice around a 2-3 horsepower advantage. A V-8 might notice 10 horsepower or higher. When you switch over from a paper filter to a K&N filter, the performance gains are instantly greater.

Can You Wash and Reuse a Filtercharger?

Another nice attribute of a K&N filter is that you can clean it after use. How to clean a K&N air filter without a kit is a popular question, and all you have to do is give it a good wash, dry it out, and then re-oil the element at the same intervals in which you would normally get it maintained. You can wash a K&N filter charger up to 25 times. It’s recommended to get it inspected at around 30,000 miles or every 12 months. If it doesn’t look like a good cleaning needs to be done, then you can just re-oil it so that the best efficiency is kept up. All you have to do is add a tiny amount of oil on the cleaner side of the element.

Looking Past The Air Filter And Air Box

Taking a deeper look at things, the engineers at K&N began to analyze the container that encompasses the air filter, which is called an air box. Before air reaches a carburetor, it must first pass through the air box, and the size and shape of a vehicle’s air box have a large impact on airflow. Air flows very similar to how water flows. It typically doesn’t want to move around corners or deal with any obstructions in its way. In a lot of cases, the air box that is used in the air filtration system is as restrictive as a paper filter element. In some severe cases, the air box might even be the biggest cause of air restriction. Air restriction in an air box can be thought of like a marathon runner breathing through a single straw.

Another example of this is an original air cleaner box covering a carburetor. In most cases, the air cleaners housings are sealed off from outside air. This means that the engine is breathing through a snorkel type of hose that is attached to the outside of the housing. Sometimes the snorkel is looped around several different hoses.

To efficiently get around this issue, a line of filter charger injection performance kits were released. They are used to bypass the restrictions that are caused by the air box. Engines that are port-injected are typically given a cone-shaped filter, meanwhile, centralized injection systems are given an open-element cleaner that gives the vehicle the chance to use all of the air that it possibly can.

Off-Roading

If you’re the type that is into off-roading in a Jeep or other vehicle, then an air filter element can be thought of as a type of insurance policy. For a vehicle to win the race, it must cross the finish line. If the vehicle sucks up too much dust and dirt, then it might not even be able to make it to the finish line in the first place.

Some consumers might think that a toss-away paper air filter is the perfect use for off-roading, but keep in mind, that tiny little bit of extra horsepower can make or break the race. When considering this, the air filter now becomes an important factor to consider when looking at the whole performance package. That is the main reason why most off-road racers will go with K&N filters. They provide:

  • The highest amount of airflow without a reduction in filtration quality, even if they happen to become covered in dust and dirt.
  • The dust and dirt don’t restrict the airflow.
  • Better performance.

During a race, a vehicle is bound to get some dust on the air filter. With a paper filter, this happening will lower performance. With a K&N filter, it will only enhance the performance. If you look at some numbers, a paper filter will flow 700 cfm (cubic feet per minute) of air at a level of restriction, but a K&N filter will flow 1050 cfm of air at the same level. If you look at vehicles with each filter in the same 24-hour race, each collecting the same amount of dust, the paper filter will flow 350 cfm of air, while the K&N flows 525 cfm of air. This proves that the K&N filter will be reduced at a much slower rate than the paper filter when put in the same conditions. With the K&N filter, the off-road racer will still have cfm to spare, meanwhile, the paper filter racer will have to replace it before the race even ends to ensure they have a decent enough supply of air to finish.

Air Filters And Racing

When it comes to racing on a clean and paved track, one might think that a proper air filter isn’t necessary and decide to forgo spending anything extra than they need. Once you sit back and actually think about the number of particles that are thrown up by other racers during the course of a race, one shouldn’t hesitate to bite the bullet and get a proper K&N air filter. Dirt, rubber from other tires, and tiny stones are thrown up from cars during many races.

Racers should stick with the K&N 360 degree open-element filter if they are seeking that extra edge of performance. Why should they choose this? Because there will be no restriction in airflow, and the increased performance might be all a racer needs to turn that second place into first. With high-speed races, a K&N filter counteracts turbulence. Other issues such as reversion, can pose another threat. Reversion is basically reversed air flow, and this happens when the pressure gets into the intake runner from the cylinder throughout the valve overlap. Reversion can create shock waves right in the tubes that then exit the open ends of the tube at certain rates, all depending on the speed of the engine. If a free-flowing air filter is installed, this issue can be resolved.

This issue is resolved by the filter creating a sort of plenum right over the opening. The air that goes through the filter is slowed down and straightened out. After that, the filter acts as a source of clean and calm air. The shock waves will then go away.

Environmental Impacts of K&N

If we say that an average vehicle has a lifespan of around 200,000 miles and that every single owner replaces their vehicle’s paper filter every 12,000 miles, they will be tossing away 197 filters every single year, assuming that around 197,000,000 vehicles are registered in the country. 197,000,000 filters being thrown into landfills every single year is a tremendous amount of garbage that doesn’t have to happen. If you multiply that amount by 12.5, which is the number of filters that an owner will be replaced over the lifespan of a vehicle, you’ll come to the conclusion that 2,462,500,000 air filters will be in the landfills every 13 or so years.

Which Air Filter To Purchase?

Finding the right air filter depends on a number of different factors:

  • If you’re wanting maximum horsepower, then the shape and size of the air filter will be important to consider.
  • A standard round air filter with a larger diameter tends to flow more air than one with a smaller diameter, but taller one. If you have a 10-inch diameter filter that is 2-inches tall, it will typically flow more air than a 5-inch diameter filter that is only 4-inches in height. The overall height of a filter should be around 1/5 and 1/4 of its diameter.
  • If the application suggests a remote mounted filter, then the shape of the filter isn’t as important. Getting right down to the specs, a pleated K&N air filter will flow 6.03 cfm of air per square inch. The highest flowing paper air filter will only allow 4.95 cfm of air to flow through it.

There is a useful formula for figuring out the smallest sized filter you can use for your purposes. The effective filtering area is the usable portion of a filter. This is determined by multiplying the diameter of the filter times 3.14 (Pi) times the overall height in inches of the filter, then subtracting .75-inch. The .75-inch is subtracted to make up for each rubber seal on the end of the element.

If you’re taking your vehicle off-roading, then these conditions usually require more filter area. Filters need to be around 1.5 to 2 times bigger than normal ones for conditions that are known to be more hectic.

Warranty On Filters

The warranty that K&N offers is on any material defects and workmanship. If you think that your K&N product is defective, it will be replaced at no charge. What is K&N not responsible for?

  • K&N isn’t responsible if any damage is suspect due to abuse.
  • K&N isn’t responsible for any damage that happens due to a damaged filter.

When it comes time to service K&N filters, ensure not to put too much oil on the element. Extra oil can sometimes get into the intake system and cause issues with electronic sensors. The filter should never be saturated and if you see any oil dripping from it, it should be washed and the process should be started over. It is recommended to also use K&N oil for the process. Oiling instructions that are included with the filter should be closely followed.

Extra Tips For K&N Filters

When you are going about installing a K&N filter:

  • Ensure to keep a lookout for gaskets, seams, and clamps for any damage or degradation. If you notice any type of damage on the seal, refrain from installing the filter.
  • If you notice any cracks in the air box, air leakage could occur around the air filter.
  • Ensure that the air filter is snuggly sealing in the air box.
  • When a new filter is installed, put a thin layer of grease around the sides of the seal. If there is an impression in the grease, then that is indicative of a good seal.
  • If engine oil makes its way into the air box, it can result in the filter shrinking and losing its size.
  • The air box should be cleaned of dirt and dust with a mildly damp cloth. Ensure that nothing gets into the air inlet when the filter isn’t in it.
  • Refrain from starting the vehicle without the filter.
  • K&N air filter cleaner should be the only product you use to clean your filter with. The rubber seal can be damaged by household cleaners.
  • K&N air filter sealing grease should be used on the surface that makes contact with the air box.
  • If you’re having difficulty in installing a filter, re-read the instructions that it comes with. Excessive force should never be used when installing a filter.

Automobile Warranty

Whatever you have heard about K&N filterchargers voiding your vehicle warranty, this is simply not true. The Magnuson-Moss warranty act that was passed in 1982 states that it is not legal for a manufacturer to void a warranty on a new vehicle if the purchaser uses non-OEM filters unless the manufacturer provides the filters for no charge. The manufacturer isn’t able to void a vehicle’s warranty just because you choose to install an aftermarket air filter.

Is It Worth It?

If you’ve been scowling the internet for auto air filter reviews, then K&N has surely popped up once or twice. Knowing the facts about air filters will help you make a wiser decision for your next vehicle. How much is an air filter? Well, K&N guarantees that you will purchase the highest quality air filter for the most reasonable price. Take a glance at the K&N air filter size chart for a filter that matches your vehicle, and you’ll never want to go back to a paper one again.