The shape and size of an air filter element can have a major influence on its ability to provide the engine with the maximum amount of air. For instance, when it comes to K&N elements, you can use the diameter of the air filter to determine the area necessary for the required air flow. In other words, size does matter when it comes to cold air intake filters. Capacity is also an important factor to consider.
It is usually measured in grams and indicates the maximum amount of dirt the filter can contain before reaching its restriction limit. This capacity depends on the physical size of the filter, more precisely on the area of the filter medium, which varies depending on the number of folds. If you compare two filters for the same application and made of the same material, the one with more folds usually has greater capacity. Although it is possible to “clean” a filter that cannot be cleaned and its useful life can be increased, it is just as possible and very easy to poke holes in it without knowing it, allowing dirt to enter the engine and, little by little, damage it.
Jon Wake, air filtration product manager at Parker Filtration (headquarters of Racor), said: “A filter can start with an initial 98 percent efficiency, but in just a few thousand miles, it has risen by a full percentage point and, when it reaches 20 to 25 inches of water vacuum, the usual maximum restriction range, efficiency has reached 99.9 percent. Some filters can be cleaned, but how you do this is very important to prevent damage and reduce filter efficiency. Keeping the air conditioning system clean is a relatively simple job, and a basic filter usually does that. It is clear that a cold air intake filter is a very important part of a car engine, and its size can have a big impact on performance.
The fuel economy of fuel-injected cars was not affected until the filter was subject to a very high restriction and, in that case, only in a small amount. Most consist of a plastic frame surrounding a pleated material that is thin enough for air to pass through, but dense enough to filter out dust and other contaminants. Unlike engine air filters, there are no real improvements in performance when switching from one brand of cabin air filter to another. Filter grease, such as the one sold by K&N, can be especially useful for sealing filters in the housing and preventing damage to the joints during inspection.
It limited the use of air filters to a small group of cars and subjected them to the same test routines used to determine EPA fuel economy ratings. The amount of air required usually increases depending on adjustment changes or other modifications that may be made to the engine. Fram offers a line of cabin filters that use activated carbon impregnated with sodium bicarbonate to better absorb odors, while others only use carbon as an element. Generally speaking, a larger filter will provide better airflow and more power, while a smaller filter will be more efficient and produce less noise.
A new fuel injection programmer was being tested and adjusted on a late-model Chevy Duramax, but serial and tight performance was slow, until it was noticed that the filter restriction indicator was red. In conclusion, size does matter when it comes to air filters for cars. A larger filter will provide better airflow and more power while a smaller one will be more efficient and produce less noise. However, capacity is also important as it indicates how much dirt can be contained before reaching its restriction limit. It is also important to note that some filters can be cleaned while others cannot.
