http://www.bmwe34.net/E34main/Upgrade/Air_filter.htm

I was reading this and just wanted to see what you guys thought before I purchased one. I know everyone has opinions but does anyone have facts like this article. I know it's a BMW but it's still a K&N cone filter.

 

uh oh.....

 

I've seen a couple cases of the filter oil gettig on the MAF... the sensive wires can be cleaned with Carb cleaner and Q-tips.

You can lose HP from hotter engine air if your running a cone open under the engine.... thats why there are cold air setups. This doesn't effect K&N replacment type filters...just the cone ones that people make themselves.

Partical filter rates are worse for the K&N...they never claimed to filter better...that were your geting more flow from. They still me engine specs.

K&Ns are still very well proven. Some of the "oil on the MAF" cases can be contribued to owners over-oiling their filters after cleaning them....only a thin coat is needed.

 

They claim they are about the same - from the web-site:

10. What is the micron rating and filtering efficiency of the K&N filter?

K&N air filter designs are tested both in house and by independent testing laboratories for air flow, filtering efficiency and dust retention. The Society of Automotive Engineers (SAE) establishes testing standards for automotive air filters. Independent testing of panel and round K&N air filters has confirmed an overall efficiency rating of over 99% when tested using the SAE J726 air filter test code. The test results provide scientific details including particle size, size distribution, testing methodology and results. The overall results establish the superiority of our filters against the “competition”. The OEM minimum specification is 96% with ISO (International Organization for Standardization) test dust which consists of a majority of 0 to 5 micron particles but some up to 20 microns in size. Test results showed that a paper filter has a 99.29% cumulative efficiency and a 96.47% initial pass. A K&N filter, with far less restriction than paper, has a 99.05% cumulative efficiency and a 97.11% initial pass.