Originally posted by Torquemonster:
Actually I've seen two tests where foam filters performed worse than cotton ones such as the K&N. Now mind you, they filtered better but overall airflow was less. Marginally more than a stock paper when when slightly dirty. The tests I saw were not on the Amzoil filter but something like Greddy. It was a large mushroom shaped foam filter.
I've seen those, too. Remember that these figures are per square inch, so in an open element most makers just make the foam "cone" bigger to compensate. Result is (probably) equal flow with better filtration. A winning combo, in my book.
But for a panel, or drop-in, where size is restricted, the cotton gauze is the winner.
I don't recall any "independent" tests, however. I've seen Amsoil's marketing charts, and K&N's marketing charts. Anybody have any impartial sources? I had one "independent" source rave about foam, but he never mentioned gauze, so not really a comparison.
