SCOPE:
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