I DID TESTING. .........changes to engine and rpm
would have to be VERY big changes for the stock BMW filter to
be inadequate. ......
My supercharged /5 went for normal mileages between STOCK filter changes;
around 20K for me;....and, I did measurements
on it in the same way I did
much later to my first R100RT:
I used an old super-sensitive aircraft gauge that is a dual
type
(separate elements, twin needles) I also have a differential
altitude instrument that is even more sensitive, and reads out in inches
of
mercury. ANY of you with ANY type of manometer, gauges, whatever,
can pretty much duplicate what I have done.
With one side of my dual gauges connected to the intake side of the
filter, the other side connected to the outlet, one can crudely
measure the
difference across the filter. If the 'piping' is properly positioned to
avoid venturi and coanda, etc., type of effects,
this really works rather
well. I have tested the stock filter on my R100RT when
brand-new and when it had over 20,000
miles. I put a REALLY filthy old
customer's filter in that bike and re-tested. ....On the SAME R100RT, I also tested a
brand-new K
& N filter that I specifically purchased for measurements (then I sold it
off my website). I tested the K & N
before oiling, and after
oiling it (considerably) with K & N filtercharger red fluid. I had an old
customer's K & N filter on the
shelf, that was quite filthy, and tested
it. I also tested it with a dirt bike foam surround added.
I also tested a BMW 2002
car filter (round type), that mounted on an
aluminum plate, sealed to the top of the lower part of the rectangular
R100RT
airbox. Also on the same R100RT. That filter was
noisy, susceptible to water damage (I never made a hat for it), but the
results of ALL my testing was pretty clear.
Bottom line: I personally, and for customers, use
the BMW stock filter with
measurements to back me up. Some time ago I had on my website for a longish time a
couple of hyperlinks to two different
websites that had the information from
independent laboratories that measured the actual particulate filtering
capabilities of
many filters, including the K & N, which were tested
extensively and the reason for the hyperlinks. The K & N was
not
favorably regarded, to say the least. The hyperlinks kept
getting messed up as the website owners played with the websites,
and I got
very tired of having to find the articles on the websites, as folks told me
the hyperlinks were not working. I
removed the hyperlinks, don't even
have them anymore....but a Google search would find them.
NOTE: I also
removed the articles for another reason...much of the
information was simply duplicative, from the one that I left,
below.
Section 2, below, has LOTS of information....copied here
so we don't have to worry about missing or moved website
information!
Section 2
This
is the full report of in-depth tests run by an independent
laboratory. AFAIK, this is available in the Public Domain
on the Internet; but I obtained
permission. This is a
2004 report, but nothing has changed. By incorporating this posting
I do not have to keep up with changes to such as hyperlinked websites, nor answer so many
questions about using
K & N filters on Airheads (or K
bikes!...cars/trucks, etc.).
This is only one
of a number of independent studies on the various filters on the
market....which include the K & N.
Note
that
our motorcycles, with the original filter replaced by a standard K &
N, do not need rejetting. NOTE, however,
that
there ARE K & N
filters that are
used in racing (or, on someone's racey-looking street bike),
that eliminate the stock filtering
setup. These put a mesh filter at the intake of each separate
carburetor.
Almost always the use of these types of mesh
filters at the intake of each carburetor WILL
require rejetting of the carburetors. These types of filters can cause problems
such as fuel frothing from vibration,
so the carburetors probably should have a support structure
added, which is tricky.
These filters also GREATLY upset the famous BMW mid-range torque curve...and
offer, in essence, NO FILTERING that means
anything at all...thus, such usage WILL wear your engine...rather fast too.
The bottom-line, in case you do not wish to read further: The K & N air filter will, in my opinion, greatly accelerate engine wear.
NOTE: This report has been on MANY sites on the
Internet, here is a prime one:
http://duramax-diesel.com/spicer/index.htm
What follows in the balance of Section 2 is totally UNEDITED by me:
"""This
report presents the results of an ISO 5011 test of several
air filters designed for the GM Duramax
Diesel. The test was independently performed under controlled
conditions using a $285,000 machine
at Testand Corp of Rhode Island (manufacturer of the
machine). Arlen Spicer, a GM Duramax Diesel
owner/enthusiast organized the test. Ken an employee of
Testand offered to perform the tests at no
charge. (These tests typically cost approx $1700.00 per
filter). Ken, also a Diesel enthusiast and owner
of a Ford Power Stroke Diesel, shared Arlen’s interest in
performing an accurate unbiased test of different
types and brands of diesel engine air filters. The filters
used in the test were purchased retail and donated
by Arlen and other individual Duramax Diesel owners. The
detailed reports from the test have been
compiled and are presented in the following pages. The final
pages of this report present the behind the test.
ISO 5011 Test:
The ISO
5011 Standard (formerly SAE J726) defines a precise filter
test using precision measurements
under controlled conditions. Temperature & humidity of the
test dust and air used in the test are strictly
monitored and controlled. As Arlen learned in attempting his
own tests, there are many variables that
can adversely affect filter test results. A small
temperature change or a small change in humidity can
cause the mass of a paper filter to change by several grams.
To obtain an accurate measure of filter
efficiency, it’s critical to know the EXACT amount of test
dust being fed into the filter during the test.
By following the ISO 5011 standard, a filter tested in
Germany can be compared directly compared to
another filter tested 5 years later in Rhode Island. The ISO
5011 filter test data for each filter is contained
in two test reports; Capacity-Efficiency and Flow
Restriction.
Capacity and Efficiency:
The
Capacity and Efficiency test report presents the test results
of feeding an initially clean filter with
PTI Course Test Dust (dirt) at a constant rate and
airflow. The course test dust has a specific distribution
of particle sizes ranging from less than 2.5 microns to
greater than 80 microns (see table below). Every
filter is initially tested at 350 CFM and the Initial
Restriction or differential pressure across the filter is
recorded in IN-H20 (Inches of Water). The filter
is then tested by feeding test dust at a nominal rate of
9.8 grams per minute with a constant airflow of 350 CFM. The
test is continued until the flow restriction
exceeds the Initial Restriction + 10 IN-H20.
At this point the test is terminated and the amount dust
passed through the filter - Accumulative Gain - is
measured. Dirt passing through the filter is captured
in the Test Station’s Post Filter. The exact amount of
dirt passed is determined by measuring the before
and after weight of the Post Filter. Similarly, the
amount of dirt retained by the Filter under test -
Accumulative Capacity – is measured by taking the
difference between the before and after weights
of the Filter. From these results the overall % Efficiency
of the filter is calculated. This test also
indicates how long a Filter will last before replacement is
required (or cleaning for reusable filters).
Flow Restriction:
This
report presents flow restriction of a clean filter resulting
from an increasing airflow. The differential
pressure restriction across the filter is reported in inches
of water (IN H2O) versus Air Flow in cubic
feet per minute CFM.
Data from these reports has been compiled and presented in the following bar graphs, Plots and data tables.
Filter Efficiency:
Filter efficiency is a measure of the filters overall ability to capture dirt.
Accumulative Capacity:
“Accumulative Capacity” is a measure of dirt holding/loading
capacity before reaching the maximum
restriction limit - Initial Restriction + 10 IN-H20.
Accumulative Gain:
"Accumulative Gain" is the total amount of dirt that passed through the filter during the test.
(Note: The Purolator was reported to
have a seal malfunction during the test and passed more dirt
than it would
have with a good seal.)
Initial Restriction:
Initial Restriction is the Filter under test’s resistance to flow at 350 CFM.
Dirt Passed Versus Total Test Time
This graph shows each the duration of each filter’s test versus dirt passed (Accumulative Gain).
(Note: The Purolator was reported to have a seal malfunction during the test and passed more dirt than it would have with a good seal.)
In the
chart above it’s important to note the different test
durations for each filter. The AC Delco filter test
ran for 60 minutes before exceeding the restriction limit
while the AMSOIL and K&N tests each ran for
20 and 24 minutes respectively before reaching max
restriction. In 60 minutes the AC Filter accumulated
574gms of dirt and passed only 0.4gms. After only 24 minutes
the K&N had accumulated 221gms of dirt
but passed 7.0gms. Compared to the AC, the K&N “plugged up”
nearly 3 times faster, passed 18 times
more dirt and captured 37% less dirt. See the data tables for
a complete summary of these comparisons.
Dust Loading:
The dust
loading curves show graphically how each filter responded to
a constant 9.8 gms/min dust flow
before reaching the maximum restriction limit.
It’s
interesting to note the shape of these Dust Loading Curves.
The AC and Baldwin filters each had
near linear responses until reaching maximum restriction.
Restriction for these filters increased at a
constant rate versus the 9.8 gms/min dust feed rate. The
other filters, most notably the oiled reusable
types, had an exponential loading response before reaching
maximum restriction. These filters had a
lower initial restriction, but they became exponentially more
restrictive under a constant flow of dirt.
Also notice the length of the curves as it shows the relative
test time for each filter (time to max restriction).
Restriction to Flow:
The
Restriction to Flow curves graphically show how each “clean”
filter responded to a steadily
increasing flow of air up to 350 CFM.
The Flow
Restriction response curves for each filter have the same
basic shape. However, note how
the AC Filter, which passed the smallest amount of dirt and
had the highest dirt capacity and efficiency,
also had the highest relative restriction to flow. The less
efficient filters correspondingly had less
restriction to flow. This illustrates the apparent trade-offs
between optimizing a filter for dirt capturing
ability and maximum airflow.
Test Data Tables:
Test Data Tables:
Test Data Tables:
Test Data Tables:
Test Data Tables:
Test Data Tables:
To be
consistent with common industry practice all filters were
tested using PTI Course Test Dust. Course dust is more
commonly used since it will produce higher % efficiency
numbers.
The Story behind the test:
First of
all, many thanks to Arlen Spicer and Ken at Testand for
organizing and facilitating the test.
Arlen is a professional Firefighter who also operates a small
tree service on the side. The tree service
is the reason he owns a diesel truck. This study was the
result of nearly a year of work by Arlen to get
accurate independent data on air filters for the GM Duramax
Diesel. Arlen originally set out to build
his own Filter Test Stand so that he could perform accurate,
repeatable and independent measurements
on the various filters available for the Duramax. Arlen
questioned the claims made by aftermarket filter
manufacturers that their filters were superior to the
conventional OEM style paper filters. After spending
many months, hours and a considerable amount of his own
money, he learned first hand how difficult it
was to perform an accurate air filter test. He found it was
difficult to maintain all the necessary controls to
insure an accurate measurement. It was at this juncture that
Arlen received a call from Ken at Testand
offering to perform the ISO 5011 test free of charge. Ken
found Arlen’s idea for an independent comparison
study very interesting and offered to do the ISO 5011 testing
using one of Testand’s industrial Filter Test
Machines. Arlen posted the news on the Internet and
immediately offers from other Duramax owners to
purchase and send filters for the test started rolling in.
Some purchased and donated filters and others
made contributions to cover the expenses and the cost of
shipping the filters to Teststand. It was truly a
team effort. The end result is the top quality data presented
in this report. The following is a quote from Arlen.
(Arlen) SPICER wrote,
“Now
that I am not doing the tests and my objectivity is not
necessary, let me explain my motivation.
The reason I started this crusade was that I was seeing
people spend a lot of money on aftermarket
filters based on the word of a salesperson or based on the
misleading, incomplete or outright
deceiving information printed on boxes and in sales
literature. Gentlemen and Ladies, Marketing and
the lure of profit is VERY POWERFUL! It is amazing how many
people believe that better
airflow = more power! Unless you have modifications out the
wazoo, a more porous filter will
just dirty your oil! Some will say " I have used aftermarket
brand X for XXX # years with no
problems. The PROBLEM is you spent a chunk of ching on a
product that not only DID NOT
increase your horsepower, but also let in a lot of dirt while
doing it! Now how much is a lot?
ANY MORE THAN NECESSARY is TOO MUCH!
Others are persuaded by the claims of aftermarket
manufacturers that their filters filter dirt "better
than any other filter on the market." Sounds very enticing.
To small timers like you and me,
spending $1500 to test a filter sounds like a lot. But if you
were a filter manufacturer and you
believed your filter could filter dirt better than any other
media on the market, wouldn't you want
to prove it? Guess what. Test your filter vs. the OE paper.
It will cost you $3000 and for that
price you will have the data that you can use in your
advertisements. Your investment will
be returned a thousand fold! EASIER than shooting fish in a
barrel! So why don't these
manufacturers do this? Hmmm? Probably not because they would
feel guilty about
taking more market share.
Now I
am not saying that ALL aftermarket filters are useless. A
paper filter does not do well
if directly wetted or muddy. It may collapse. This is why
many off-road filters are foam. It is
a compromise between filtering efficiency and protection from
a collapsed filter. Now how
many of our trucks collapse their filters from mud and water?
However, if a filter is using
"better airflow" as their marketing tool, remember
this....Does it flow better? At very high
airflow volumes, probably. BUT, Our trucks CAN'T flow that
much air unless super-modified,
so what is the point? The stock filter will flow MORE THAN
ENOUGH AIR to give you ALL
THE HORSEPOWER the engine has to give. And this remains true
until the filter is
dirty enough to trip the air filter life indicator. At that
point performance will decline somewhat.
Replace the filter and get on with it.
Hopefully the results of this test will do 2 things. Shed
some light on the misleading marketing
claims of some aftermarket manufacturers and/or give us new
insight on products already
on the market that are superior to our OE filter. I stand for
truth and will eat my words publicly
if my statements prove wrong. I appreciate all of the help
and support that you members
have offered in this project. It would simply be impossible
without your help. A huge thanks
to Ken at Testand for his willingness to take on this
project. I would be spinning my wheels
from here to eternity without his help… SPICER”
Our
thanks to Arlen and Ken for making the test happen and
providing the valuable test results
for the benefit of all.
Sept 2004
Section 2 ends here.
An abbreviated
source:
http://forums.nicoclub.com/debunking-the-k-n-myth-why-oem-is-better-t180100.html
Rev:
08/12/2009: Modify article for easier reading (edit
Section 1); add Section 2. Decrease line widths so displays
better on small monitors
03/02/2011: change URL so when E-mailing article URL,
there is no problem creating a hyperlink (eliminate spaces in
the URL)
10/03/2011: make it very clear what is copyrighted, and
that I obtained permission to post the report in its
entirety.
05/08/2012: clean up the article a bit for clarity. NO details
changes.
© Copyright, 2012, R. Fleischer, on MY commentary ONLY