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Re: The K&N Filter Controversy (archive)

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Posted by Bear on August 28, 2001 at 05:57:10:

In Reply to: The K&N Filter Controversy posted by Mark.C on August 28, 2001 at 03:12:04:

I have been intrigued with the different "facts" surrounding this so have done a little research myself.
It seems scientific tests (filter efficiency ,pressure drops etc.) of automotive filters in the public domain are rare. The only ones I could find and reference were three from MIRA (Motor Industry Research Association) in Britain commissioned by K&N Europe in the early 90ís. Also British magazine "FAST CAR" did one in June 96.
Here is the interesting bit-they all show "pleated cotton-gauze" filters to be very efficient ! around 97% - this puts them on par with paper- Also they flow well WHEN CLEAN.
Foam holds more dust than any other type but also filters poorly and doesnít flow as well as pleated cotton-gauze -read K&N.
Paper filters filter well but donít flow well.
To summarize:
A "pleated cotton-gauze" K&N filter (and I assume other brands of the same design)
flow superior to all other types and filter well. The disadvantage is: because the filtering media has a small surface area compared to foam and paper once dirty the pressure drop across them becomes excessive. If left too long as the pressure drop becomes high I think debris will be sucked through, maybe this is where the "they let lots of dirt through" idea comes from.
The results seem to indicate as long as they are cleaned often they are superior !
Now I have never bought one myself but in view of these results I am seriously considering it.
I have no association with any filter suppliers manufactures etc.

I think the consensus is that a drop in K&N will give you cleaner air (at least for a while) but since it still resides in the engine compartment will add no power. However, if it were a cone filter and it was plumbed to an outside air source (say behind the fascia) it then has the potential to produce a bit more power. My daily driver is a 1998 Neon DOHC and I plumbed, with ABS tubing a system thay puts a cone filter just behind the cutout in my fascia,and it does give a feel of a bit more power. I do clean it every 12000 miles, but it is not terribly dirty at that time.


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