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MG MGF Technical - K&N and tear & wear: interesting story

Read this today on the Porsche Pete Boxster Board.
Curious to know what you think about this (old) info...


I've seen a lot of posts about K&N filters. I thought that some of you might be interested in the following information, which was posted recently to the Mercedes M-Class mailing list:

>Subj: K & N filters
> To: John M. Saturday, January 21, 1995 5:14:10 PM
>From: George Morrison
>John: If I wrote "subjective" I meant "objective".. I was
>responsible for evaluating re-usable air filters
>for a major construction/mining company that had
>hundreds of vehicles ranging from large earthmovers
>to pick-up trucks and salesmen's cars. This study
>was embarked upon due to the fact that we were
>spending upwards of $30,000 a MONTH on paper air
>filters. Using them one time then throwing them
>away.. I inititated the study in that I was convinced
>that a K&N type filter or oiled foam would save us
>many dollars per year in filter savings, man hour savings,
>and of course engines as these would filter
>dirt better than paper. (yes, I had read the K&N ads and was
>a believer)
>Representative test units were chosen to give us a
>broad spectrum from cars right through large front
>end loaders. With each unit we had a long history
>of oil analysis records so that changes would be
>Unfortunately, for me, every single unit having
>alternative re-usable air cleaners showed an immediate
>large jump in silicon (dirt) levels with corresponding
>major increases in wear metals. In one extreme
>case, a unit with a primary and secondary air cleaner,
>the secondary (small paper element) clogged
>before even one day's test run could be completed.
>This particular unit had a Cummins V-12 engine
>that had paper/paper one one bank and K&N/paper on
>the other bank; two completely independent
>induction systems. The conditions were EXACTLY
>duplicated for each bank yet the K&N allowed so
>much dirt to pass through that the small filter became
>clogged before lunch. The same outcome occured
>with oiled foams on this unit.
>We discontinued the tests on the large pieces almost
>immediately but continued with service trucks,
>formen's vehicles, and my own company car. Analysis
>results continued showing markedly increased
>wear rates for all the vehicles, mine included.
>Test concluded, switched back to paper/glass and all
>vehicles showed reduction back to near original levels
>of both wear metals and dirt. I continued with
>the K&N on my company car out of stubborness and at
>85,000 miles the Chevy 305 V-8 wheezed its
>last breath. The top end was sanded badly; bottom
>end was just fine. End of test.
>I must stress that EVERYONE involved in this test
>was hoping that alternative filters would work as
>everyone was sick about pulling out a perfectly good
>$85 air cleaner and throwing 4 of them away
>each week per machine...
>So, I strongly suggest that depending upon an
>individual's long term plan for their vehicles they simply
>run an oil analysis at least once to see that the
>K&N or whatever alternative air filter is indeed working
>IN THAT APPLICATION... It depends on a person's priorities.
>If you want performance then indeed the K&N is the
>way to go but at what cost???
>And no, I do not work for a paper or glass air
>filter manufacturing company nor do I have any affiliation
>with anything directly or indirectly that could
>benefit George Morrison as a result..

I would say at a guess we are talking here of a quarry works type company - he mentions large front end loaders - where the extremes of dust are not something that you and I are not likely to come across on a regular basis. However it is interesting to read and it would be nice to see a more scientific comparison test done.

Ted Newman

Interesting thread Luc. Only caveat I would give people before they start panicking and tossing out their K&N filters is that the test in the above thread were done for a MINING/ CONSTRUCTION company and i doubt the majority of us F drivers are subjecting our cars to those kind of conditions daily (unless London's polution levels have gotten worse over past years...)

But then again, K&N does boast their filter's ability in off-road conditions... Plus with all the reported problems with the F, I would be HAPPY to see my F live beyond 85,000 miles!!!!


Damn, Ted beat me to the punch...

Sorry Mike :-)

But it is nice to see that two guys at opposite ends(sides) of the earth agree on this subject.

Ted Newman

Great post Luc, really useful information.

I had read that the K&N allows the engine to breath better by filter less but that in every day use on the roads this should not be a problem with the oil filter collecting what the air filter misses.

I also suspect it adds more wieght to Roger's argument that you should change your oil at least twice a year!

The clear message is don't fit a K&N is you intend to use the car for mining......



>> I also suspect it adds more wieght to Roger's argument that you should change your oil at least twice a year!

Or use a better oil filter ...

Thanks for bringing this information to our attention Luc. Facinating read!
Every filter company says that their filter has the best particulate absorption, but this extreme case appears to suggest that paper elements are better still.

Perhaps this is not surprising: the smaller the filter pore size, the greater the resistance to air flow and hence lower power... Increasing the surface area of the filter should help get around that particular problem I would have thought though.

I wonder if we can get a filter company to comment?

This application does seem somewhat extreme though- and silica particulates are very small...

Personally, I clean and re-oil my K&N every 12 months.

Rob Bell

I would simply add this, which Ted can no doubt remember as well as me.

For many many years standard air filters were so bad that any tuning involved removal of them altogether and substituting with a bell mouth ram pipe. Apart from making a sporting gurgling sound, performance was improved. Long term it was always accepted that there was a risk of ingesting foriegn objects that could damage your engine, but these would be larger items that cause immediate problems. The effects of dust inhalation and consequent increased general wear was not a large enough issue to worry about in the usual UK type climate. (Drier climates were always advised to have a filter.)

The general scenario here is that without any form of filter, subject to not ingesting a stone, increased wear is going to be very difficult to quantify in the UK type climate, subject to certain qualifications. As such adding a filter which may pass a greater volume of smaller particles when compared to a standard paper unit is going to make comparisons even more difficult.

The qualifications I would add concern the nature of the cold air pick up. Here I suggest that the standard under car cold air pick up as supplied with the K&N kit for the MGF is one which poorly positioned, in terms of drawing from the air which carries considerable debris raised by vehicle movement. The choice by Rover to locate the 'cold' air intake where they did, at the back of the engine, may be a consequence of the disturbed airflow further forward, which carries a high weight of debris.

Roger Parker

As Rog says NO filter was ythe order of the day for maximum performance, in fact fitting of filters was as much about preventing fires from blow backs as it was about keeping the air intake clean.

Ted Newman

This thread was discussed between 21/08/2000 and 23/08/2000

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