One of my co-workers showed me an article today on a K&N air filter test he found on the web. It was performed by a mechanical engineer who seems very reputable, and appears to not have any ties to a company, so it seems completely unbiased. The testing methodology seems to be solid as well.
What he found is a bit disturbing.
I am no longer comfortable with my 2 K&N's in my Crossfire. I may go back to the stock paper elements.
It is a moderately long read, but very interesting. Here are some quotes:
"So what do these results mean? (referring to air flow testing for restriction) For one, there is very little pressure drop across any air filter, and the difference between the best (K&N) and worst (paper) is very small. Yes as total power output increases, air flow increases, and differential pressure would also increase. So a K&N probably does yield some power on higher output race motors where every last ounce of power must be squeezed out. On lower powered street cars, it is probably not much of an improvement over paper."
So that is what he discovered about the flow. Not too surprising. It is what I expected.
But here is the disturbing part:
"Did you see the dirty 2nd filter? Well that is the result of experiment #1. The test subject was the K&N air filter. Yes it let many particles pass through. The K&N was tested for 501 miles........Well there is a clear pattern on filtration ability compared to both flow and the type of filtration media used. The "high performance" cotton gauze and foam filters do not filter as well as some have claimed. I actually received an e-mail from K&N stating their filters filter within 99% of the OEM filters. This may be true, and 1% may not sound like much. I contend that 1% over many miles, may be important. Really, it is up to each individual to decide. The poorer flowing filters, remove more particles, and the better flowing filters remove less particles."
Here is the link so you can read it yourself. I bet this has gone around before, so I apologize if I am stirring up an old topic. All I am sure of is that I don't like the feeling that I may have added a few ponies at the expense of engine life.
http://www.bobistheoilguy.com/airfilter/airtest1.htm