Are foam air filters better?

In this article, we discuss whether foam air filters are better than the other types of air filters for the engine that are available commercially.

Are foam air filters better?

Yes, foam air filters are better than the standard OEM filters that are made from special grade paper. However, a K&N filter outperforms both of them quite significantly.

Why are aftermarket filters on the rise?

Air quality has been degrading steadily over the past several years. This is more pronounced in urban areas, especially in places which are prone to traffic congestion. 

Amongst the many contributors to air pollution, traffic-related air pollution (TRAP) is one of the major contributors. 

In some of the major cities in the world, such as Beijing, Delhi, Los Angeles, and so on, TRAP causes poor air visibility and hazardous air conditions.

Therefore, many governmental organisations have mandated vehicular exhaust emissions in order to combat TRAP. 

The introduction of Euro emission standards, as well as greenhouse gases reduction programmes have helped to enforce these changes. Amongst these, aftermarket air filters for vehicles have also seen an increase in usage. 

With people being more environmentally conscious, as well as looking for ways to improve the efficiency of their vehicles, these filters have been finding a larger audience.

Furthermore, aftermarket air filters claim to offer many benefits over the OEM filters, such as low flow restriction, high dust-holding capacity, long life or service-free designs, high gravimetric and fractional efficiency, and much more.

OEM air filters

OEM stands for Original Equipment Manufacturer. OEM air filters are the engine air filters that are used in a stock version  of a vehicle. Usually, the price of these filters are included in the total cost of the vehicle. 

Stock filters frequently use a unique grade of paper for the filtering element. Please don’t be deceived; this isn’t the same type of paper that we use to write on. 

It’s a custom-made version that can catch dirt and other particles. Its main benefit is its inexpensive price and ease of replacement. 

The filter paper may appear to be flimsy, but it actually works fairly well if you replace it on a regular basis. The obvious disadvantage is that this slows down the air, which many believe prevents the engine from operating at maximum capacity.

Most stock or standard OEM air filters are constructed out of pleated paper or foam filter components, as well as fibrous materials with small enough holes to catch solid particle matter or dust in the air.

Air filters tend to become clogged with particulate matter as a result of high pollution levels, and it is advised that you clean or replace an air filter at every regular service of your automobile. 

The air filter has a direct impact on the volume of (clean) air delivered to the engine; if the pores are too small, it may provide greater filtering but inhibits air flow. 

Additionally, if the filter becomes clogged with particles over time, the engine receives less air, and thereby receives less oxygen.

K&N Filters

K&N’s classic high-flow air filters are made with 4-6 layers of quality cotton gauze pleated between coated wire screen mesh instead of a normal paper media. 

Cotton breathes more easily than paper, allowing for more airflow, less restriction, and improved engine performance.

A standard paper-based filter accumulates dust on its surface over time, but a K&N filter has many layers of fibre that retain dust particles. As a result, a K&N filter is said to hold more dirt per square inch than a paper filter.

Foam filters

Everything is cleanable in the realm of aftermarket filters. Most aftermarket filters use oil as the medium to capture dirt, which is then cleaned and reapplied, while others are dry type filters that are simply washed and dried. 

In any case, aftermarket filters are always reusable in some fashion. So we won’t go into detail about it because it’s something you should anticipate and shouldn’t have to question an aftermarket filter maker about.

Foam, something you sit on every day, sleep on at night, and find in your morning latte and even filters? The first point to remember is that filters are filters. 

They must either obstruct or capture dirt to prevent it from spreading. Most aftermarket filters use heavy oil on the media to trap dirt. 

This enables for a more open filter element to flow more freely while still filtering. Some dry filters actually block more than they collect. 

Very tiny gaps in the filter prevent dirt from entering through. This is good for filtering, but not so much for flowing when it’s dirty.

Paper vs Foam vs K&N

You may be wondering, which one amongst the three is the best for your vehicle. We shall draw an intercomparison between the three to answer the question.

Paper filter

Paper filters, on the other hand, are formed of compacted fibres. The crevices between these strands act as minuscule apertures through which air must travel. 

These pores become clogged with dirt and dust particles one by one. When a hole is sealed, the air has to find another way through the medium. 

The resistance to air movement increases as the filter gathers more dirt because there are fewer and fewer pores left open, and as restriction increases, horsepower and fuel economy decrease. 

However, the paper must be thick and/or the fibres must be firmly compressed and dense to achieve minimal filtering criteria. 

As a result, paper components that offer suitable filtering are designed to impede air passage. Any paper element that could flow as much air as an equivalent K&N would not provide safe filtration.

Foam filters

The foam construction filter has been proposed as a possible better replacement to the traditional paper kind in recent years.

Refer to the steps below to see why the concept has its own set of issues, and while some have been advertised as cleanable and re-oilable, it is important to ask: have you ever tried to clean one?

Foam components always appear to fall into two classes to us, based on several tests:

  • Those that filter effectively yet limit your engine’s ability to produce power, and
  • The other group allows the air in, but the dirt frequently makes its way in as well. The dirt that remains in the centre of the element, at least according to some users’ experience, cannot be cleaned off.

K&N Filters

The K&N air filter is a little trickier. An oiled cotton fabric traps airborne dirt particles in this one-of-a-kind pattern. These dirt particles attach to the filter’s exterior and become part of the filter’s filtering media. 

Between the cotton fabric and the pleated aluminium screen is a cotton fabric. Pleating improves surface area, promoting air movement and extending service intervals. 

When compared to a flat element like foam, pleating exposes five times the surface area.

Because there are no tiny pores to clog, dirt particles deposited on the surface of a K&N element have very little influence on air flow. Particles are halted and maintained in suspension by crisscrossed cotton strands.

Because air must first travel through the dirt particles trapped on the surface, a second type of filter action occurs as the filter collects trash. 

This implies that when the filter absorbs dirt, the filtering effectiveness of a K&N element improves. 

After 50,000 miles of street use, a K&N E-1500 (the most popular domestic V8 element) filter will flow 60% of its full flow capacity, according to tests. 

Furthermore, because a fresh K&N filter flows half as much air as a comparable paper element, even after 50,000 miles, that same filter will give all of the air the engine requires.

Dirt captured by a paper element, on the other hand, will permeate the fibres, obstructing airflow at a proportionate rate. In other words, when a paper element becomes filthy, its performance suffers significantly. 

Air flow through a paper element can drop by as much as 70% over a service interval of 14,000 miles. The effectiveness of K&N’s oiled cotton gauze medium has been demonstrated several times.

According to service professionals, some big vehicles have recorded over 100,000 miles with no reduction of air flow. This is partly due to the fact that a clean K&N filter can flow half as much air as a similar paper element.


We discussed the various types of air filters commercially available – the standard OEM paper filters, and the aftermarket filters, particularly foam and K&N.

Although foam offers more advantages than the paper filter, a K&N filter outperforms both of them quite significantly. Therefore, foam filters are good, but some aftermarket filters are much better in terms of efficiency.


What’s the difference between K&N filters and other filters that look similar?

Both airflow and filtration efficiency are critical to engine performance. Some companies design filters that provide high airflow by greatly reducing filtration efficiency, which can risk engine damage. 

K&N filters are designed to provide high airflow while also maintaining exceptional filtration. As the appearance of K&N filters has become popular, many companies have started offering products that mimic the appearance of K&N filters, but do not provide the same level of quality and protection.

Are K&N filters better for the environment?

Yes, K&N filters are better for the environment. K&N High-Flow Air Filters are designed to last for the life of your vehicle. If you assume an engine life of 175,000 miles-and replace your disposable air filter every 15,000 miles-only one K&N air filter will be used during the same period in which eleven disposable air filters are discarded.

This helps to reduce the waste generated in terms of air filters that one would need to discard on a frequent basis as in the case of the standard OEM filters, thereby reducing the toll on the environment.

How many times can I wash and reuse a K&N filter?

K&N High-Flow Air Filters can be cleaned and re-oiled using a K&N Recharger kit as often as is reasonably necessary. K&N drop-in replacement High-Flow Air Filters typically require servicing once every 50,000 miles under normal highway driving conditions, and the larger filters included with K&N intake systems can go up to 100,000 miles before needing to be cleaned (under normal highway driving conditions). Follow this link to view complete cleaning instructions.


Leave a Comment