Very interesting feature about K&N/Cotton filters.
This is very interesting....Kinda makes me wonder whether CAI/Drop-ins are worth it in the long run. Discuss.
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Well, most of us know the most well known brand of cotton gauze filter. We'll call them "Brand X". Well,
Brand X, appears to have pretty good air flow characteristics, at least significantly better than pleated
paper filters. Also, their filters are guaranteed to last for 1,000,000 miles or 10 years - far longer than a
paper air filter ever could. As a result, even though you pay quite a bit for them, you'll probably spend
less over the life of your vehicle than you would on paper filters.
I do find it somewhat comical, though, that their warranty covers their air filters for 1,000,000 miles or
10 years. That's 100,000 miles per year. How many people do you know that can drive that many miles
in a year? Most people won't get much more than 200,000 miles out of a Brand X filter under a 10 year
warranty. Granted, that's still quite a long time and would offer significant long-term savings over
conventional air filter purchases. But, you have to admit, it's not REALLY a 1,000,000 mile warranty for
99% of vehicle owners - most people will never drive that far. It's a marketing tactic, and a fairly good
one, I have to admit.
AIR FLOW VS. FILTRATION EFFICIENCY
Brand X filters DO seem to provide enhanced air flow to your engine, thereby increasing horsepower.
You wouldn't find so many racing engines using them if they didn't. So, if you're looking for
performance, Brand X does offer that. In addition, they have kits for modifying your air box to provide
even more air flow, as opposed to just using a drop in filter. Again, for performance minded folks, this is
a bonus, I suppose.
Unfortunately, I find no conclusive evidence that a Brand X filter has any better filtration efficiency than
a typical paper air filter element. In fact, until very recently (early 2002) there was no reference to
filtration efficiency testing on ANY Brand X website I had been to - weather the company site or a
distributor site.
I suppose that doesn't necessarily mean the data didn't exist, but if Brand X filters provide better
filtration efficiency, why wouldn't it say so in their literature. It only makes good sense to publish positive
information about such an important benefit. If I sold Brand X filters, I'd certainly be mentioning it,
wouldn't you?
The truth is, although they talk incessantly about increased air flow and horsepower, any past reference
I've ever seen to Brand X filtration efficiency stated something similar to: "Brand X developed an oil
WHAT ABOUT COTTON GAUZE FILTERS?
impregnated cotton air filter gauze which exceeds the minimum filtration standards".
That's not too impressive to me. Standard paper filter elements achieve that. They basically have to in
order to be sold in stores. And, although Brand X indicates that the filtration efficiency of their filters
increases as they collect dirt, so does the efficiency of paper filters. Paper just happens to lose air flow
much more quickly.
Important News Regarding "Brand X" Filters
As of March 2002, Brand X appears to have testing data on their website which indicates an initial
efficiency of approximately 97% and a cumulative efficiency of just slightly over 99% on the SAE J726
air filter test. Of course, Brand X wants to brag about these results, but I'd like to make note of a few
important issues.
First, the test data is from 1999. Now, I'm not saying that makes the information dated. If there have
been no changes to the Brand X filter construction since then, the data is still valid. However, if the data
has been around since '99, why is it just being published now? If it shows their filter to be so wonderful,
wouldn't it have made sense to publish it back in '99, when the tests were run?
Second, the J726 test is only useful when put into context. Many variables within the testing parameters
are adjustable depending upon the application the filter is being tested for, etc. For instance, there are
two different air boxes that can be used on this test which could yield different efficiency numbers for
the exact same filter.
In addition, you're not required to use the same contaminant every time you run the test. Not only is
there the option of using either AC Test Dust or Glass Beads, but you can also choose the micron
levels to test at. With glass bead testing, you can get very specific and only test beads of a very narrow
micron range if you like. With AC Test Dust, there are numerous different "grades" of dust you can use
which range from extremely coarse to extremely fine.
A "coarse" AC Test Dust will have very few particles under 20 microns, whereas a fine test dust will
have a very high percentage of particulate matter under 20 microns. Although in years past many J726
tests were being run with coarse test dust, this trend is changing. Since it's been established that the
majority of automotive engine wear is caused by particles in the 5 to 20 micron range, more and more
of these J726 tests are now being run with fine test dust so as to more closely approximate the
conditions the filter will encounter when in consumer vehicles.
So, I find the new Brand X filter test data to be of little use in the grand scheme of things. First, they've
used the coarse grade test dust which doesn't really tell us how well the filter will remove the particles
which are most damaging to your engine. Second, since there is no way to guarantee that other filter
manufacturers have used the same parameters for their J726 tests, there is no way to compare the
Brand X results to other manufacturers' test results.
If Brand X wanted to show their filter superior to other filters, they would have had their independent lab
run the J726 on comperable competing filters using the exact same testing paramaters that were used
on their filter. Then, at least you could see a side by side listing of efficiencies using the same testing
specifications. In addition, if they wanted to show real world performance of their filters, they would
have used fine grade test dust so the testing more accurately reflected actual engine conditions seen
by most vehicles.
And, just for comparisons sake, I did an Internet search for J726 test data on pleated paper filters. I
didn't find much, but I did find a couple filters with test data. Each showed initial efficiencies of just over
99% and cumulative efficiencies approaching 100%. Of course, testing for other pleated paper filters
might not be as good, but these results are better than the Brand X filter results.
I could do some more research and make some phone calls to determine if these tests were run with
coarse or fine AC Test Dust, but either way, the results are better than the Brand X results. And, if they
were run with fine test dust, then the filtration efficiency of these filters seems significantly better than
the Brand X filters tested.
Now, please remember, any comments I've made about the Brand X filters are my opinion only. But
that opinion is based upon the information available, provided both by Brand X and other
manufacturers. In addition, I've seen J726 testing which actually did pit the Brand X filter up against two
comparable filters (one foam and one traditional pleated paper) using the same J726 test parameters
for all filters. The Brand X didn't fare very well in this test. Do I know that those results weren't tampered
with? No. Do I know the Brand X results weren't tampered with? No.
I have also seen more recent testing comparing the Brand X filter to comparable paper and foam filters
using identical test parameters which shows the Brand X getting stomped by both filters in the
efficiency category. However, it is important to note that this testing was not based upon the J726 test
parameters. It was a more simplified testing apparatus. But, the logic behind the test seems sound, and
all parameters were kept the same for each filter.
Take this information with a grain of salt and do some of your own research into this area. All I'm trying
to say is that you might want to give a little more thought to using something other than Brand X if your
concern is engine protection. I have my doubts as to whether the Brand X filter line will serve you as
well in this category as a paper filter. Do I have conclusive proof? No. Do I have sufficient evidence to
point in that direction? I think so. SO WHAT. BETTER AIR FLOW - NEARLY EQUAL FILTRATION
Of course, you might say, "So, what. If I can increase my performance by increasing air flow,
while still maintaining nearly the same filtration efficiency, I'm still better off. Besides, I won't
have to replace my air filter every 10 to 20,000 miles. Sounds like a good deal to me."
At first glance, that might seem to be the case. However, let's discuss what I said earlier in this chapter
about the relationship between air flow, filtration efficiency and engine wear. I think you'll see the
potential problem that I'm focused on.
MAKING SENSE OF AIR FLOW & FILTRATION
Let's just assume that there are 10 grams of dirt sized 20 microns ("coarse" test dust size) or greater
per 10,000 gallons of air that enters your engine. And let's also assume the engine receives about
10,000 gallons of air every half hour.
It could be any ratio of air vs. dirt, it really doesn't matter for the purposes of this discussion. It's the
comparison percentages that matter.
If the numbers above are assumed, let's also assume that a paper element is 99 percent efficient at
removing particles of 20 microns or larger (J726 test data suggests that). It then stands to reason that
every hour, 9.9 grams of dirt particles (99% of 10 grams) would be filtered out and 0.1 grams would be
allowed to enter your engine.
Now, let's assume that the Brand X filter provides just 10% greater air flow than a paper filter, but the
same filtration efficiency. That means that over the same hour, 11,000 gallons of air would enter the
Brand X equipped engine (10% more air than the paper filter).
According to the assumptions made above, there would be 11 grams of dirt over 20 microns within this
amount of air (at 10 grams per 10,000 gallons of air). At 99% efficiency (the same as the paper
element), over the same one hour time period, 10.89 grams of dirt would be trapped by the filter
and .11 grams would enter the engine.
Now, that might not seem like much of a difference, .1 grams to .11 grams, but consider it as a
percentage. That would be 10% more dirt entering your engine! Of course, when you think about it, that
only makes sense. 10% better air flow with no real increase in filtration efficiency SHOULD lead to 10%
more dirt in your engine.
IS THAT A BEST OR WORST CASE SCENARIO?
The Brand X website actually claims at least 50% more air flow than traditional paper air filters
and the J726 test data suggests that, at best, Brand X offers slightly lower filtration efficiency
than traditional pleated paper filters. So, I would say the numbers above are very conservative
and indicate what I would consider to be a best case scenario using Brand X filters.
ARE YOU SCIENTIFICALLY CERTAIN OF THIS?
No. I should make it clear that I don't have any scientific studies on Brand X filters to indicate
increased engine wear (although I have caught wind of some oil analysis testing which showed
increased levels of "dirt" in an engine after a switch to Brand X). I also can't say with absolute
certainty that Brand X filters don't have better filtration efficiency than a paper filter, since I
don't have any recent J726 testing that compares them using the same test parameters.
However, based upon the evidence I do have, I'd say it's likely that, at best, they filter almost
as well as a traditional pleated paper filter.
So, if that's the case, no matter how much the Brand X filter increases air flow, the potential for engine
wear would seem to increase just as much. If Brand X only gives a 5% increase in air flow, then you'll
only see the potential for 5% more engine wear. But, if you only acheived 5% better air flow, is it even
worth it? How about a 30% increase in air flow (which is unlikely in real world applications)? Is a
potential 30% increase in performance worth the potential for increased engine wear? Not in my car.
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Very interesting feature about K&N/Cotton filters.
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