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From Fri Sep 3 12:45:34 1999
for <>; Fri, 3 Sep 1999 12:45:31 -0700
by (8.8.8/8.8.8) with ESMTP id NAA19296;
Fri, 3 Sep 1999 13:44:39 -0600 (MDT)
Date: Fri, 03 Sep 1999 13:44:37 -0600
From: Jim Conforti <>
To: albert jenab <>
Subject: Re: [E36M3] Filter data questions

albert jenab wrote:

> This is what wasn't clear from the raw data. The K&N gets to a certain
> g/sqft of dirt faster, mostly due to its smaller area. I guess the
> crossover point is shown on the hand-sketched graph on the last page, it is
> not evident from the other plots.

Yes.. it's a combination of "Plot 1" and "Plot 2"..

If you want, I can do it all in Excel this weekend..

The "hand sketch" is that of the engineer who was explaining it all to me.. actually, I called them last nite (late) and learned a lot about how you can use "fine" test dust but get results better than "coarse"..

Here's how.. if the "tester" doesnt use ultrasonic waves to prepare the dust flow, smaller particles will AGGLOMERATE into larger ones and it makes your test LOOK really good.. but it isn't "true"

> You have made a serious claim regarding a product
> many of us have on our cars.

I'm making no "claims".. I'm reporting data.. that was done independently by a 3rd party who also is a BMW CCA member.. he happens to work at, and hence has access to this level of filter certification lab.

The "techies" there in the lab are also "car guys" like you and me, so they took the time to do these tests for us.. because we couldn't have afforded their services ;)

Now.. I believe what they tell me 101%, so I pass it on to y'all..

If anyone doesn't believe it, then simply dig deep for the cash to have tests conducted yourself.

Do however note that the methods and dusts/etc used are "standards" and the scientists in the lab are without a doubt the top in the country if not the world in the "filtration" field.

> Would love to see it. Try as I might, can't seem to let go of all that
> math training. If the particle size distribution of the dust used is
> similar to that seen in typical automotive applications, then you have made
> a very strong case against the K&N. If it isn't, then you haven't. I
> guess the only missing link would be matching it to a test procedure used
> by automotive manufacturers to protect their engines. Some sort of filter
> characteristics vs. particle size vs. wear data.

I have requested the data.. as soon as I get it, I'll pass it on..

Of course, which "dust" ruins the motor best, depends upon the motor and the clearances inside which determine the thickness of the hydrodynmaic lube films. Also the combustion chamber properties, as some "dust" even though it is in the "damage range" is small enough that it "burns up" in the cylinder..

They picked the dust, not me.. and they (filter expert/car guys) thought that ACCTD was most "representative" of what's out in the environment.

I defer to their expertise.. as they had no axe to grind.. they were not employed by BMW nor K&N, and ITG wasn't even in the picture then.

(I actually found out about ITG thru some friends at McLaren in the UK when I was BITCHING about the test results and looking for a PAPER CONE filter!)

> You are trashing
> an established product and if it sucks, then you had better be prepared for
> a lot of engineering-oriented people to ask for details.

I'm not "trashing" anything Al.. Common Sense tells you that there is no such thing as a free lunch.. if you have two filters effectively the same order of magnitude of size, and one flows sufficiently more, then SOMETHING else is going "down".. Efficiency, Life, Cost, something.

Again, all I'm doing is reporting a scientific finding.

I havent even started on what happened when we replaced "replacement filter A" with "replacement filter B" on the dyno.. Because we did.. we tried K&N, K&N clones, HKS "mushroom" filters, and ITG.. We bought all of them.. just to see what would happen.

I'm also not saying "don't use K&N".. what I'm saying is that I think *I* won't use it.. here's why.. and here's what *I* recommend.

Likewise, because I won't do to your car what I won't do to mine, I have included the same type of filter in our new intake kit..

The kit is Dyno tested.. dyno proven.

'nuff said.. for me, the case is closed


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