Well, if these filters pass that much dirt with "course" dust then how exactly would they work better with "fine" dust? The question was specific about K&N and while I wasn't calling out any particular brand, your obviously an Amsoil salesman. I recognize that this test is several years old and not comparing the latest technologies but I'm sure if you pulled up Amsoil's own pre-2004 filter tests they would show that they outperformed every other filter on that page. Who should the average consumer believe, an independent test or one supplied by the manufacturer of the filter in question?
Mike My build thread
1979 CJ7, FI 5.0L Ford, NP435, D300, Full floated D44 Detroit, D30 Detroit EZ Locker.
This debate can go on and on and I have seen quite a few posts on this forum about air filters. I personally use a K&N filter on my dune buggy which see's only action in the sand dunes of southern california. True I clean my filter after every weekend out. But Ive had that buggy for 6 years and had it torn down and rebuilt last summer, and my mechanic loved the fact that the engine looked great.
For most of us, something like a K&N filter is just not necessary. We rock crawl, and we trail ride (well most of us, theres those that do mudding and I really cant comment on what they use), an ordinary filter will work fine for us. I use an ordinary filter on my jeep and my carb is clean so for me why change whats already been working...
I don't think it matters what air filter you run, as long as it's not some walmart piece of junk.
They key is to properly maintain the filter and replace it when needed, so could we all quit arguing over which is better. I personally don't mind the oil bath air filter in my jeep, it's pretty old school but it works.
Hmmm... Thinking "Outside the Box" a little here. It seems to me that 2-stroke engines need more or better air filtration than 4-strokes, as the fuel/air mixture is actually run through the lower end of the crankcase, and thus surrounds the main bearings and rod. So, one would assume that 2-strokes need better filters than 4-strokes. And, what does every major manufacturer of 2-stroke high-performance engines run for air filters? Oiled foam style. So, without getting into brand specifics, I would assume that oiled foam filters do a better job than do paper filters. But, and this is a BIG BUT, with a dirt bike filter, it is assumed that you will clean and re-oil it after every race/day riding. This is just basic dirt bike maintenance, and it's not usually considered a big deal. But, how many of us are going to want to clean and re-oil their filter after every Jeep ride? Probably not many. So, and again, this is all theory and thinking out loud, I guess I would believe that the oiled gauze or foam filters would be the best filters if you were going to do maintenance pretty much every day, but the convenience factor or paper style filters, and our desire not to be cleaning and oiling a filter every single day, might make the paper filter a better filter for real-world situations.
I guess if I were racing my engine and needed the absolute best filtration then I would use oiled foam or gauze and clean it after EVERY run, but for a Jeep that gets wheeled and driven to soccer games and to the beer store and etc., maybe a good paper filter is the way to go. I have an oiled Edelbrock filter currently, and I think it does a pretty good job, but I haven't done any extensive comparison testing, either...
I'll answer this for you.
There is a very specific reason foam filters are used on dirt bikes. Because paper filters will fall apart when wet and they are susceptible to catching fire.
Early dirt bikes used paper filters. The problem with them came when riding in wet conditions. The paper elements would either swell and choke the motor or fold up and be ingested into the engine. The paper was also much more flammable than an oil soaked element.
Different bikes have different filtration elements available. Standard motocross elements are designed for maximum airflow. These are not designed to protect the engine over the long haul. This is why most manufactures recommend that you clean the element after every ride and re-ring the top end every ten hours of riding time to maintain maximum power output. Solid enduro bikes use a double filter to help clean the air further. These are much more restrictive, but will catch much smaller particles. My IT's run an outer/inner foam filter and very little passes into the intake tract.
Guys running sand have it the best, since the sand is too course to pass through the foam.