Air Filters

[xelhan]

Interesting information regarding air filters

[ford38v8]

Being of simple mind incapable of fully understanding all test methods and data, the results of such data presented being so unquestionably in favor of one over all others in every test has me thinking how many tests were omitted for reason of contrary expectation?

[JSeery]

The bottom line of the testing is what you would expect the denser the filter medium the more dirt it traps and the more resistance there is to air flow, the less dense the medium the less dirt that is trapped and the higher the flow rate. Who would have guessed!

[Kurt in NJ]

The K&Nfilters don't stop much, I always cringe when it is called a upgrade to rip out the innerds of a oil bath and put in a k&n

Another filter to look at is the capture size of a full flow compared to a bypass oil filter--- and that many full flow filters run in bypass non filtering mode a lot more than you would expect

[tubman]

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Well, here's my real life experience. When I got the engine in my '67 Corvette rebuilt and installed, I got it to the state where it would run ALMOST perfectly. It had an occasional "stumble" when going down the road; not very often, but enough so it was annoying. In trying to track down the problem, my first suspect was a mismatched power valve. To check it out, I installed a temporary vacuum gauge, so I could see how the readings matched up with the actual power valve rating. To get the vacuum gauge hooked up, I had to run the car without an air cleaner. As soon as I did this, the stumble disappeared. To make a long story short, with a stock air cleaner I had an occasional stumble, while without one, the car ran perfect.

The first thing I did was buy a new top of the line filter (I think it was a WIX). That seemed to help a little, but did not eliminate the problem. My next attempt was to drop a bunch of money into a K&N filter. As soon as I installed it, the stumble became more prevalent, enough to cause driveability problems. Took the K&N off, and did a test drive with no filter, and it ran perfect; put either filter back on, and the "stumble" came back, mild with a stock filter, worse with the K&N.

All of this took a lot more time and effort that I am stating here, but I finally came to the conclusion that there was something restricting the airflow. The ultimate solution was to get a premium 14" air filter that was 4" high rather than the 3" that came stock (luckily, it fit under the hood). Stumble gone, 100%. I drove the car the last half of the summer with NO stumble.

I had been chronicling this on the H.A.M.B., and of course, I got all kinds of varying input. The one fact that came through load and clear was that nobody liked K&N filters; not one positive comment. Needless to say, I share the opinions of the first two responders to this thread.