I've heard a few people say that a K&N filter will let in more dust then the stock filter, but I'm not 100% convinced. K&N makes the claim that their filter is actually MORE effective at stopping dust and fine particles than a foam filter is, due to the smaller pore size of the filter material. They also say that the dirtier it gets the more effective it will be at blocking dust, though the performance will suffer then because less air will be getting through.
I'm not sure I really buy their argument either. (Though I did buy their filter)

 

Doesn't the ability of a filter to capture a particle depend on how fast the particle is moving and how small of a hole your trying to stop it with. I know you can't stop it with the hole, but (you understand).

If the K & N's filter is the same surface area and the same measurement of micron size hole, then it would perform the same as stock.. Would everybody agree w/ this? So how do you get more airflow without changing the pressure? I can only think of 2 ways. Increase the size of the hole, or, increase the surface area of the filter. Someone above said that the K & N doesn't stop dust w/o oil. Because the oil helps block up the big holes and creates a sticky surface for the dust to stick to. Personally, I would choose a large surface with a hole size of 10 microns. I don't understand this oiling the filter. If the filter doesn't stop the dust on it's own, then get a different filter. It would be cheaper and more consistent to just toss the dirty filter in the trash then to adjust the needle valve because you put a little too much oil on the filter.

I can't remember the last time I rinsed and reused a filter on any of my cars...

 

I think you hit the nail on the head though. The K&N filter has more surface area than a conventional foam filter, which allows for smaller holes but increased airflow.

The reason you never oil the filter on your car is that it's not designed to run in an off road environment 100% of the time. Vehicals that will spend alot of time in a dusty environment, such as a dump truck, are often equiped with an oil bath filter, where the filter is not only coated in oil, it actually sits in a bath of oil. They work great.

 

Wouldn't you think that they could take human error out of the equation (too much oil, not enough oil) by creating a disposable filter that we didn't have to do anything too but use it and replace it? But, keep airflow & particle entrapment to the maximum. Maybe I'm asking too much, but it seems logical to me. Please don't tell me to design one, I have enough on my plate as is. [img]i/expressions/face-icon-small-happy.gif[/img]