If you could kindly post a link to any review that includes these two filters that shows the K&N filtering better?

 

Seems to me that testing oil is at best a second order way to rate filter efficiency. The way that the filter industry rates filters is with the use of a particle generator, a discrete particle analyzer, and a known differental pressure across the membrane. This allows a direct measurement of particle penetration at a variety of particle sizes.

Comparing the K&N to the apexi isn't as simple as saying the apexi doesn't get oil so it isn't as efficient. The filter membranes are clearly two different pore sizes.

The K&N uses a larger pore size which makes it less efficient for larger particle sizes (probably rated at 25 microns or so. They make up for this by adding oil to allow particles to adhere to.

The apexi relies on a more efficient filter (probably 5-10 micron). The trade off is that the pressure drop will be greater and therefore the airflow will be less per square inch of filter face. They make up for this by designing a filter with more surface area. More surface area allows lower pressure drop and therefore more airflow.

I'm not saying which one is more efficient, but my money would definately be on the apexi

 

Can you show the opposite?

However, for one that is non-biased, repeatable, and relevant on an engine with oil analysis to back it up? I doubt it.

 

I agree the filter industry is wrong.

You can NOT measure the filtering ability of a filter under ACTUAL conditions unless you perform oil analysis. This is not a one time test that's definitive, however over several analaysis you will be able to tell. There are MANY factors that are not repeatable in a "lab" scenario, such as what happens when you get 50K miles on both filters. One the Apexi loses flow and the K&N supposedly gains.


Foam vs. foam, paper vs. paper, cloth vs. cloth, an oiled filter will outperform a dry.

Do you mean smaller particle size? If so, according to K&N

The most important principle for our use is diffusion, which deals with the laws of physics that govern the motion of very small dirt particles. Small particles are highly affected by the forces in the air stream. Forces such as velocity changes, pressure changes, turbulence caused by other particles and interaction with the air molecules cause these very small particles to become random and chaotic. As a result, these particles do not follow the air stream and their erratic motion causes them to collide with the filter’s fibers. This phenomenon enables an air filter to capture dirt particles that are much smaller than the openings in the media. In addition, the way that dirt collects or loads on the K&N filter is very different. A paper filter exhibits "surface loading" which means dust collects only on the surface of the media. In contrast, K&N filters exhibit "depth loading". The multiple layers of cotton fibers provide many levels of dust retention. This characteristic allows the K&N filter to hold significantly more dirt per square inch of media than the average paper filter. Utilizing these scientific principles, K&N has been able to design an air filter that is very free flowing while also being highly efficient at removing dirt from the air.


Where do you get 5-10 micron or 25 micron for the K&N? The K&N filter has 98%+ efficiency with particles ranging from 5.5 microns to 175 microns. Do you have Apexi filtration results from the SAE J726 procedure? I doubt it. http://www.knfilters.com/images/factstab1.gif and http://www.knfilters.com/images/factstab2.gif Surface area of both filters is assumed to be equal, so the Apexi "funnel" cone that supposedly reduces the pressure drop by 10% can easily be outweighed by a larger K&N. Not to mention what happens once the filters actually get dirty. Assuming the Apexi has a 5 micron impaction ability, then once it gets dirty the pressure drop will increase. Assuming the K&N's 25 micron impaction ability, the filter will still be able to use diffusion and capture the smaller particles as it's still depth loading. So, at what point do you throw away your Apexi to keep the pressure drop from rising too much?

My money wouldn't. Apexi doesn't have some "super" media that can trap particles any better than any other similar media type filter out there. The fact that it's not oiled means that it must rely on impaction, which is only going to trap larger particles THROUGH SURFACE LOADING. Now if you oiled an Apexi with it's 10% pressure drop reduction, you might have something to argue. However, I doubt the Apexi uses depth loading, but until I know what the media is made of I don't know whether the K&N multi-layer cloth is better or the Apexi composite media.

 

http://forums.maxima.org/showthread....hreadid=224341

 

Let me know what you think. I hooked my 9" K&N cone filter directly to the stock accordian piece. I also removed the crankcase hose (which normally attaches to that long metal tube that you asked about in your other post) and replaced it with a breather filter. I'm pretty happy with the setup.