Fram's Joe Eidukaitis and Don Scott, as lab manager and product engineer, respectively, have a great deal of knowledge about filter design. Much of that knowledge runs contrary to popular belief, such...
Fram’s Joe Eidukaitis and Don Scott, as lab manager and product engineer, respectively, have a great deal of knowledge about filter design. Much of that knowledge runs contrary to popular belief, such as the question of foam racing filters, which Eidukaitis feels compromise filtration. On the subject of flow and restriction in air filters, he comments: “The most simplistic view is that smaller pores stop lots of particles, but will plug faster. There has to be a happy medium. Both OE manufacturers and aftermarket companies are aiming for change intervals that are reasonable. The only way to have a five-year change interval, for example, is to have very poor efficiency. The other solution is to have a good filter that’s 98 percent efficient, and tow it behind your car. It’s the need for adequate surface area that’s the problem. Even with oil filtration, you have to strike a reasonable compromise.”
Don Scott notes that the design of modern engine compartments can make the installer’s job especially difficult: “With under hood real estate shrinking, some housings are put in pretty awkward positions. We know that if a filter isn’t properly installed, air may bypass around the seal. A person leaning over a fender must take the time to make sure that the filter is seated properly. It’s a concern.
We’re getting requests to do the same job in a smaller area. To make better, smaller filters, we’re looking at different media, surface treatments, and different fibre shapes. Even the combination of filter and housing can affect performance. One thing to keep in mind is that at 98 percent efficiency, two percent is getting through, so a little film inside the housing doesn’t mean that the filter isn’t doing the job. Normally contaminants in the 5 to 20 micron range are the particles that affect your engine. Those are the particles that are associated with scuffing and scoring. Anything bigger is like a boulder to the engine. Smaller ones are getting critical with modern engines, because of the tighter clearances.”