K&N air filters, are they any good ?

-- The colored filter that you are referring to is BEHIND or downstream from the filter being tested. It is used as a second filter to see what passed throught the first filter. The darker the color, the more crap came through the first filter. The lighter the color, the more crap was trapped by the first filter. Every day is a good day- it's just that some are better than others.

mcalister wrote:

Engines are engines. And air filters are far more critical for tractor than cars - both becasue the environement is worse and becasue tractors spend a significant period of time near maximum power settings.

I don't actually "hate" K&N filters but I am offended by many of the claims. I just think K&N Filters are over-hyped and belong in a class of "performance enhancers" just above supposed performance enhancers like split fire spark plugs, fuel line magnets, tornado air swirlers, etc. I can believe that for a highly modified engine K&N Filters might make some difference at the peak of engine performance compared to the OEM paper filter (that was sized for a completely different situation). I just don't believe they are beneficial for street vehicles with basically stock engines. For all the vehicles I am aware of, the stock air filters are sized to provide more than adequate flow without significant restriction. Even K&N doesn't claim they filter better than paper filters or even that they filter as well. The K&N ads spend a lot of time talking about improved air flow and some time talking about how well they filter without really making a firm comparison. The ads play a sort of shell game. Clean K&N filters flow better than dirty paper filters and dirty K&N filters filter as well as clean paper filters, but what does this mean? I don't know. I do know that paper filters do a very good job of removing dirt. I also know that for a stock engine, in normal use there is virtually nothing to be gained from the installation of a K&N air filter. So why would I take the risk of installing a K&N air filter? Most of the flow tests where K&N Filters are compared to paper filters show that a K&N will flow more air at some particular pressure drop. This seems a backwards test that is designed to "prove" that the K&N filter media is more porous. I conceede this. This sort of test doesn't reflect the pressure drop at the actual flow rate required. The proper test would be to measure the pressure drop at the flow rate required. In most cases paper filters are sized so that the pressure drop in actual use is trivial. In order to minimize the pressure drop across an air filter, you can simply increase the size of the filter (i.e., you could achieve the same flow rate as a K&N filter of a given size by going to a larger paper filter).

I have never found a truly definitive test of air filters. There are lots of tests and opinions avialable on the internet. Here are a few:

?OpenDocument&,8695641 I espeically liked this test (bassically a K&N Advertisement):

A 14" diamter by 4" high K&N filter with a special open top filter, and a flow smoother stack produced only 6% more horsepower at 6000 rpm that a 9" diameter by 2" tall paper filter with a closed top and no stack. If you can only get a

6% improve at 6000 rpm and WOT with such a highly slanted test, what improvement do you think you will get with filters of the same size. The K&N filter had approximately 280 square inches of filter area compared to around 57 square inches of filter area for the paper filter. Even with almost five times as much filter area, the K&N only provide 6% more power. If they had been running a fair test, they would have compared the K&N to properly sized paper filter.

Ed

Nope, you need to read/look again. Any of you die-hard K&N fans look at the site? What do you think? It might change your mind about the filtering efficency of K&N, and the real amount of air flow increase.

Wrong. The darkness is on the secondary filter and it measures the dirt that got PAST the PRIMARY filter. (I'm not shouting, only emphasizing) Thus, the K&N is under performing compared to the paper WIX or the two Miata and whatever filter.

Ever read the ScamsOil warranty? It's similarly impossible to get coverage under, which no doubt it why they can claim no one ever has.

-- Elbridge Gerry, of Massachusetts:

"What, sir, is the use of militia? It is to prevent the establishment of a standing army, the bane of liberty. . . Whenever Government means to invade the rights and liberties of the people, they always attempt to destroy the militia, in order to raise a standing army upon its ruins." -- Debate, U.S. House of Representatives, August 17, 1789

The automakers consider the oil fouling of MAFs due to K&N type filters to have become a significant enough problem to issue TSBs about it.

-- Elbridge Gerry, of Massachusetts:

"What, sir, is the use of militia? It is to prevent the establishment of a standing army, the bane of liberty. . . Whenever Government means to invade the rights and liberties of the people, they always attempt to destroy the militia, in order to raise a standing army upon its ruins." -- Debate, U.S. House of Representatives, August 17, 1789

"SERVICE - ALL BUICK, CADILLAC, CHEVROLET, GMC TRUCK, ISUZU, OLDSMOBILE, PONTIAC AND HUMMER DEALERS

Subject: A/T Shift, Engine Driveability Concerns or SES Light On as a Result of the Installation of an Aftermarket Reusable, Excessively Oiled Air Filter -- 2004 and Prior Cars and Lt Duty Trucks and

2003-2004 HUMMER H2 Message #: VSS20040056

Corporate Bulletin Number 04-07-30-013 will be available in SI on March 18, 2004.

Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Installation of an Aftermarket Reusable, Excessively Oiled Air Filter

Models: 2004 and All Prior Cars and Light Duty Trucks

2003-2004 HUMMER H2

DO THIS First, Inspect the vehicle for a reusable aftermarket excessively oiled air filter

DON'T DO THIS DO NOT repair under warranty if concerns result from the use of a reusable aftermarket oiled air filter.

The installation of an aftermarket reusable, oiled air filter may result in:

1. Service Engine Soon (SES) Light On

1. Transmission shift concerns, slipping and damaged clutch(es) or band(s)

2. Engine driveability concerns, poor acceleration from a stop, limited engine RPM range

The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur.

When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively oiled air filter. The MAF, GPS reading should be compared to a like vehicle with a OEM air box and filter under the same driving conditions to verify the concern.

Transmission or engine driveability concerns that are the result of the installation of an aftermarket reusable, excessively oiled air filter are not considered to be warrantable repair items"

-- Elbridge Gerry, of Massachusetts:

"What, sir, is the use of militia? It is to prevent the establishment of a standing army, the bane of liberty. . . Whenever Government means to invade the rights and liberties of the people, they always attempt to destroy the militia, in order to raise a standing army upon its ruins." -- Debate, U.S. House of Representatives, August 17, 1789