<VV> Re: Air filters (LONG)

[Mark Chapman]

SNIP--
Well, the arguments used by some aftermarket air filter companies have never made  any sense. Increased air flow is only an issue if, for some unexplainable reason, the factory intentionally over-restricted the airflow with thier filter design. Don't think so. Increasing air flow 
(besides increasing contaminate flow) does nothing but lean up the mixture unless you have a corresponding change in the fuel supply........Bottom line - as I've said many times - if you could get a noticible increase in hp just by using filter brand X then why didn't the factory use them?  A 10% increase in advertised hp by just using brand x air filter? WOW! Lon
--UNSNIP

This is an  overly-simplistic view of aftermarket air filters...

Having dealt with race cars and motorcycles for the past 30+ years has led me to believe that increased power required things other than air. Yeah, on carburated engines, we routinely rejet due to increased fuel requirements at WOT when using either oiled open cell foam or oiled gauze elements. In racing, where every fraction of a hp matters, I can see the need.

Many people think that because they have a filter that costs often as much as $50 more than a porous, folded paper type element that they dont have to maintain it. This is absolutely not so. Oiled foam or gauze elements require CONSIDERABLY MORE maintenance due to the nature (porosity) of the element itself. 

PROPER use of open cell foam technology allows great airflow without sacrificing dust retention capabilities. Open cell filter foam is a honeycomb of tiny interlocking cells of the same sizes. These cells maximize airflow, while making it tough for dirt to pass, since there are no straight through passageways. The addition of foam filter oil increases the foams ability to retain dirt and dust particles. As the foam cells block the dust particles, the filter oil traps these particles, much like flypaper. Since these cells run through the depth of the foam, dust and dirt is trapped throughout the filter rather than just on the surface?where it can restrict airflow.  Conversely paper and gauze type filters work on a ?Go?No Go? principle. Paper filters are essentially flat surfaces with openings that allow air to pass through. Dirt smaller than these openings passes through, while dirt larger than the openings stick to the surface, clogging the filter and restricting the airflow!
 . The result is continuously decreasing air flow. 

Open cell foam type air filters offer increased flexibility to meet the demands of changing conditions. Open cell foam filtering elements are made up of three individual elements; the primary filter, the qualifying filter and the outerwear. Used in individually or in combination, these elements provide the flexibility to meet changing conditions. For example, many racers choose to use just the qualifying filter when qualifying. Since there is only one car on the track and peak performance is the goal, the qualifying filter provides adequate protection against dirt and debris while maximizing airflow. Conversely in dusty/dirty conditions or for longer races, most drivers use all three elements to provide strong airflow while providing increased protection against dirt and debris.

Open Cell Foam air filters are among the easiest filters to maintain, however, must be maintained regularly. Washing the foam Filter elements in soap in water results in a virtually complete release of dirt and dust particles. After reapplying filter oil to the primary filter element, the system has been restored to like new condition and is ready for use. Traditional paper and gauze type filters are much tougher to clean and can never be restored to maximum efficiency with cleaning. Paper and gauze filters generally never fully release the dirt and dust particles that are embedded in them. Since paper is weak and swells when it comes into contact with moisture, in many cases, cleaning is almost impossible. Even blowing the filter out with compressed air can result in tears or damage to the filter that further reduces its effectiveness.  

You guys probably didnt want to read this much about air filters, but I like for all sides of a story to be told.

Just my $.02 worth. Your mileage may vary.

Mark Chapman