K&N filters bad?

[Phil Payne]

> I have been informed that K&N filters are bad for my car. I would like to see
> the data on this before I install this filter in my car. I will stay with
> factory filters if the data indicates that K&N filters could allow damage.

We did a test on one about five years back.  I got two identical lint-free cloths from a photo
shop - we took an ur-quattro (MB engine) and cleaned the dome over the air mass sensor paddle.
Then we fitted a new Audi filter and drive 1,000 miles.  Then we wiped out the dome with one
of the cloths, put in a freshly oiled K&N, and drove another 1,000 miles.  When we wiped out
the dome with the second cloth we had a clear comparison between their filtering abilities.

We pitched the K&N over the hedge and put the paper one back in.

There is a general rule on aftermarket bits - if they really did perform some sort of miracle,
the manufacturers would fit them as stock.  Especially a part like a renewable air filter,
since nowhere is the cost pressure greater than on servicing.

Ask K&N to name _ONE_ engine manufacturer who fits their product as stock.

-- 
  Phil Payne
  http://www.isham-research.com
  +44 7785 302 803