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Discussion Starter #1
Background Information

It has been over two years since the idea of an air filter comparison study was taken up by myself and members of Dieselplace.com. I began the roller-coaster ride by challenging the seemingly unreal claims of after-market air filter manufacturers. Claims of unsurpassed filtering ability, airflow to spare and dirt holding capacity far beyond any “obsolete” paper filter seemed enticing. These claims were “validated” by graphs, comparisons and “data” found on filter boxes, on websites and in sales literature. After closely reading these marketing claims I found the information provided to be misleading, unscientific and unfair to the consumer. I challenged many filter manufacturers to come forward with real scientific data to back up their claims. I would receive literature, e-mails and sales pitches, but no data of any significance. At the same time I would repeatedly hear my friends on Dieselplace.com exclaim about their purchases and how they were doing themselves and their trucks a favor by dropping some dough on their new air filter that was an obvious “improvement” over the stock filter. They justified their purchase by “reciting” the same misleading sales jargon that was so cleverly created by the marketing teams. It seems that the marketing was working. My problem is that I have compassion for hard working individuals that spend their hard earned money on a product that promises one thing and yet may not be able to deliver.

Since the filter manufacturers were so reluctant to come forward with real data to back up their claims, I decided to find out for myself. In haste, I built a test stand and came up with a method of testing filters so that we could compare, side-by-side, the different filters on the market. I had a lot of support and began receiving a LOT of air filters from members. Then scientific reality hit. Variables! I could not control humidity, temperature, and a host of other rather important variables that made my data look, well, useless. I put the idea on hold for a couple of months while I decided on the next step. This is when we got our big break.

I got a phone call out of the blue from Ken at Testand Corp. I had contacted Testand Corp. in Rhode Island several months earlier for advice. I had shared my idea with Testand, an independent testing facility, about a side-by-side comparison study. He was calling to tell me that he had been thinking about my idea. He was not only excited about the idea, but he was offering to actually PERFORM the lab work for us at no charge! All that he needed was the filters! Well, there was no need to twist any arms. The members of Dieselplace.com came together and filters were coming to Rhode Island from all over the country. The subsequent study has reached far and wide as the only independent ISO 5011 comparison study of air filters available to the consumer.

The K&N Report

Why They Invited Me.

Recently K&N sent me an e-mail asking me to contact them. They expressed admiration for my dedication with regards to the air filter study but felt that their product was misrepresented. They felt that the data in our study showed a filtering efficiency that was uncharacteristically low for their product. They knew that to try to defend themselves in the forums was a no win proposition. After careful thought they decided the best option was to invite me out to their facility and show me what they do. They made me the offer and after consulting Dieselplace forum members I decided to accept their offer.

The visit to their facility was Feb.7 and Feb.8, 2006. The primary goal was to run ISO 5011 tests on a couple of filters so that they could show me that the test results in our study do not coincide with the test results that they see regularly in their lab and at an independent testing facility.

What About Their Laboratory

K&N has been using laboratory data to back up their R&D for a long time. For many years they would send filters to Southwest Research Lab, an independent ISO 5011 testing facility. Today they have their own lab that is a part of their entire facility in Riverside, CA. The lab is about a year old now and it was built by Southwest Research. They use this lab to conduct quality control and R&D. They also regularly test competitors filters to keep up on trends and changes. This lab meets ISO 5011 requirements and is in constant use by a full time staff at K&N. In addition, K&N continues to regularly send filters to Southwest Research for duplicate testing. The purpose for this is to validate their own results. This lab is where we spent the majority of our time.

ISO 5011

ISO 5011 is the International Standard for testing automotive air filters. The standard outlines all aspects of testing air filters including equipment, environmental controls (temperature and humidity), required accuracy of measurement, and methods for conducting a test. For equipment, environmental controls and accuracy of measurement the standard leaves little to ponder. The lab either meets or does not meet the requirements. The last item is methods for conducting a test. Note that this says “methods”, not “method”, for conducting a test. This point is important because the standard does not specify a single method for conducting a test. Instead, the standard specifies a range of options for conducting a test. The exact method chosen is essentially the choice of the laboratory and the customer. This brings us to comparability. Two filters tested identically can be compared directly. On the other hand, two filters tested with different methods, though both tests may be valid and may conform to ISO 5011 requirements, may NOT be directly compared by their results. It simply is not a valid comparison. The use of ISO 5011 data in advertising, therefore, can be speculative also. For instance, for company “A” to say that according to ISO 5011 tests we have a 99.97% efficiency is meaningless unless the exact method of testing is also specified. In other words, beware that it is possible to “select” a method of testing that will optimize the performance of a filter and still be ISO 5011 compliant.

What We Did

The first thing we did Monday morning was to go to an auto parts store of my choice and buy filters off the shelf. We bought a K&N 33-2135 and a paper filter that was tested in our study. We then toured the lab and got right to testing. We spent the first day testing the paper filter and discussing matters of MAF sensors and other issues which will be discussed below. The second day we tested the K&N 33-2135 and discussed issues of marketing and advertising which again will be discussed below. The testing we did included filter efficiency, dirt holding capacity and resistance to flow as is the typical protocol for a complete ISO 5011 test.

The Results Of The Testing

As I mentioned before, K&N wanted to show me that the results published in our study did not match the results that they see in their lab and from Southwest Research. We tested both the paper and K&N filters in an identical manner at the K&N test lab. However, as will be discussed below, the method of testing at the K&N test lab and at Testand were not identical and therefore the results of the tests at K&N can in no way be directly substituted for the results achieved at Testand Corp.

On day 1 we tested the paper filter. They wanted me to see that the results that K&N’s lab achieves for paper filters closely resembles the results seen in our study. The results of the paper filter efficiency at the K&N test lab were a few tenths of a percent lower than the efficiency that we saw in our study. The test for dirt holding capacity was actually higher by a couple hundred grams and resistance to flow was similar.

On day 2 we tested the K&N 33-2135. This is the panel filter designed for the Duramax Diesel airbox. This filter is a bit unusual as it has 6 layers of cotton gauze vs. the usual 4 layers of gauze found in most of their replacement filters. We ran the test in an identical fashion to the paper filter tested on day 1. The results of the test showed that the K&N 33-2135 had an efficiency of 98.74%. This is compared to an efficiency of 96.8% in our study. The dirt holding capacity also improved to 276 grams from 211.6 grams in our study. The resistance to flow was again similar to what we saw in our study. I was satisfied that the tests were conducted in an ISO 5011 compliant fashion and found the K&N lab technician to be extremely thorough and conscientious.

How This Compares To Our Test Results

K&N showed me that the results that we got in our study were not what they were accustomed to seeing in their lab. In addition, K&N showed me independent lab results from Southwest Research. These lab reports mimicked the results that we saw in the K&N lab. So, according to lab work compliant to ISO 5011, the K&N product showed performance that was significantly improved over the Testand results. So, which results are more accurate, the K&N and Southwest Research results or the results in our study? The answer to this question is not an easy one. Essentially, the results of the K&N lab results and Testand’s results are both valid and at the same time cannot be directly compared for many reasons.

As I mentioned before, ISO 5011 allows a range of methods for conducting equally valid tests. The results of one test employing a certain method, however, cannot be substituted for another test employing different methods. Here are the differences in the testing method at K&N vs. Testand.

(1) K&N tested the filters with the filter in the Duramax airbox. Testand tested all of the filters in a universal filter housing. Without doing extensive testing on these two methods it is impossible to know the implications of this. Filter housings are all different and will change the way dirt is introduced to the filter. Whether or not this difference was significant in the results achieved by K&N vs. Testand remains a solid “maybe”.

(2) ISO 5011 allows for incremental testing of a filter. The purpose of incremental testing is that a filter’s ability to remove dirt changes as it loads with dirt. Incremental testing allows a lab to see how the efficiency changes as the filter goes from new to clogged. Typically a filter’s efficiency improves as it clogs because the dirt behaves as additional media, increasing the efficiency of the filter. So, a new filter is more likely to allow dirt past the media than a used one.

When conducting a test one of the “options” is the dust feed rate. The feed rate can be 0.25, 0.5, or 1.0 grams of dirt/cubic meter of air introduced to the filter. K&N tested the filters under a much lower initial dirt feed rate of 0.25g/cu. meter for the first 60 grams of dirt and then completed the test at 1.0g/cu. meter for the remainder of the test. Testand, on the other hand, ran the entire test at 1.0g/cu. meter (9.8g/minute at 350 cu. ft/ minute). The implications of this may be speculative, but I would have to conclude that a slower initial feed rate to a clean filter could improve it’s initial efficiency%. This would lead to an improved overall filtering efficiency when compared to a filter tested under a more demanding initial feed rate as was the case with the Testand testing.

(3) ISO 5011 also allows for a choice in the method of introducing the airflow. The choices are constant airflow or variable airflow. Constant airflow uses a single rate of flow for the entire test. In this case, 350 cu. ft. per minute. Variable airflow uses 350 cu. ft. per minute as the maximum airflow and then VARIES the airflow every minute for the duration of the test. The variations are on a predetermined schedule that typically goes like this: 100%, 50%, 80%, 20%, 60%, 40%, 80%, 30%, 80%, 60%, 100%, and then the cycle repeats. This is viewed as a more real world test and it introduces a dynamic not found in a constant airflow test. With variable flow testing the filter experiences a continuous change in differential pressure resulting in a “capture and then release” of the dirt particles within the test media. According to an independent testing facility, variable flow testing is a more challenging test for filter medias and will commonly result in significantly lower efficiency numbers.

The Testand test employed variable flow testing. The K&N test employed constant flow testing. Again, both test are ISO 5011 compliant. However, given the differences in testing methods the two results are in no way directly comparable


Other Issues

MAF Sensors

A lot of the members asked me to look into the MAF (Mass Air Flow) sensor issue. The issue revolves around a belief that the use of oiled filter media can lead to contamination of the MAF sensor with oil and dirt residue causing the sensor to fail. The MAF sensor is a critical part of the fuel delivery and emissions control systems of the vehicle. If a MAF sensor fails for any reason it must be replaced and they are expensive.

K&N has a warranty department and MAF sensors are their primary focus. K&N has done extensive testing to try to CAUSE MAF sensor failure and they say they have been unsuccessful. They take all claims very seriously, but they continue to battle the belief that oil on a sensor will cause it to fail. According to K&N, MAF sensors can fail for a variety of reasons not related to oil or other types of contamination.

The most common claim by customers about MAF sensor failures, according to K&N, begins with the mechanic. It plays out like this.....A customer has a check engine light come on, The mechanic sees the K&N filter and concludes that it is a bad MAF sensor from oil contamination, The mechanic replaces the MAF sensor and denies warranty because of the after-market filter, The mechanic clears the code from the customer’s vehicle computer, The customer files a warranty claim against K&N.

What K&N Does With A Claim

When K&N gets a claim they do a thorough investigation. Be sure, if you are ever told that you have a bad MAF sensor, to ask for the part. Without the part, K&N cannot investigate the claim. K&N will test the MAF sensor on their flow bench and they will compare the readings to an identical MAF sensor. K&N keeps a library of MAF sensors just for this purpose. If they don’t have one on site, they will immediately purchase one. K&N also sends the MAF sensor to a lab so that the residue, if any, on the MAF sensor can be analyzed for composition.

According to K&N, the majority of MAF sensors that they receive are perfectly fine. They conclude that the mechanic replaced it under an assumption of failure without first testing it. There are methods for a mechanic to verify whether or not a sensor is actually bad. These steps, in these cases, were apparently not performed. K&N also said that the majority of bad sensors that they get are not contaminated, suggesting that the failure was for a reason OTHER THAN oil contamination.

After K&N’s investigation of a claim, the customer will receive a report outlining the findings. If the report shows that the MAF was NOT failed, or that it was failed but not contaminated and therefore failed for another reason, this report may be used for reimbursement for the repair if the vehicle is under warranty.

A MAF sensor replaced on a non-warranty vehicle when the MAF sensor was not at fault should also be reimbursed by the facility doing the repair. A failed sensor that was not contaminated is the fault of nobody and becomes the responsibility of the vehicle owner.

I asked K&N how many MAF sensors they have found to be faulty with the K&N filter to blame. Surprisingly the answer was NONE. From what I saw at K&N, it does appear to me that they do take claims very seriously and they do a thorough investigation. Again, it is imperative that the parts be retained in order for K&N to do an investigation. Also, it should be suggested to the mechanic that he check the MAF sensor to ensure it is failed before replacing it. As I mentioned before, the majority of MAF sensors coming to K&N are not failed. According to K&N, in the majority of the cases, had the computer been simply cleared of the code the problem would have been solved. A check engine light does not always mean a failed sensor or other problem requiring repair.

Advertising And Marketing

I suppose this next section brings us full circle to the root of the Dieselplace air filter study. As mentioned in the “Background” section of this report, my motivation stemmed from an unwillingness to believe everything I was told. Marketing and advertising has as its primary goal to maximize the financial potential of a product. I want to be fair to K&N and preface this section by stating that I am in no way singling out K&N. My original frustration when the Dieselplace study began was with the claims of the oiled-foam filter manufacturers. The oiled-foam filters were all the rave on Dieselplace at the time and their claims were the centerpiece of discussion and scrutiny.

Upon close inspection of K&N’s product claims I came across a section of their website called “Air Filter Facts”. The first time I read this rather detailed section of their website I thought I had read multiple “facts” that were absolutely untrue. As I read the claims closer, however, I realized that much of what they were saying was not untrue at all. Actually, they were making very TRUE statements in a context that was IMPLYING a rather fantastic claim about the product without actually saying it. In other words, the common reader/customer could easily read the information and come away with an IMPRESSION that was not necessarily actually written. This is possibly what a good marketing team does. Present perfectly true statements in such a way as to give the reader an impression of the product that is BEYOND what is actually true. Nothing untrue stated, no foul. However, this is another example of how cautious consumers must be. It takes a very discerning eye to see the difference. Here are some examples.

Under the heading of “Filtration 101-A Deeper Cut” the statement is made....”A paper filter exhibits “surface loading” which means dust collects only on the surface of the media. In contrast, K&N filters exhibit “depth loading”. The multiple layers of cotton fibers provide many levels of dust retention. This characteristic allows the K&N filter to hold significantly more dirt per square inch of media than the average paper filter.”

The impression that many readers may get from this statement is that a K&N filter can trap and hold significantly more dirt than a paper filter. However, the fact that a K&N filter has significantly less “square inches” than a paper filter makes this statement unimportant from a practical standpoint. The statement K&N makes is true. However, the impression that many may get from reading this statement is untrue. In fact, the opposite is true. An average paper filter will actually hold and retain more dirt than a K&N filter.

Under another heading called “Paper vs K&N” the statement is made...”Additionally, as a paper filter becomes more and more clogged, the pressure inside the filter drops while the atmospheric air pressure (approximately 14.7 psia at sea level) outside the filter remains the same. It’s like using your lungs to draw air out of a plastic milk bottle. When the pressure differential becomes too great, the bottle will collapse. The same thing could happen to your paper filter, although it is unlikely. But what will happen could be just as severe. An excessively high pressure differential created by a restricted filter can literally pull dirt particles through the paper medium.”

This statement is entirely true, FOR ALL FILTERING MEDIA. It is misleading to suggest that the paper filter may collapse, and the impression given regarding the dirt particles being pulled through the paper media is that the K&N is immune to this phenomenon. The truth is that all media are capable of letting dirt through under extreme pressure differentials. K&N is no exception.

The above quote continues....”In other words, the performance of a paper filter, i.e. air flow through the filter and its ability to protect your engine, DECREASES near the end of its service interval.” The first part, a decrease of air flow through the filter, again applies to ALL filter media as it loads with dirt. The K&N is again no exception. As far as the inability of a paper filter to protect your engine near the end of its service interval, this statement is completely untrue. A paper filter, just like most filter media, will actually deliver a HIGHER filtering efficiency near the end of its service interval and therefore BETTER engine protection.

My last example involves the use of air flow data. Under the title of “AIR FLOW COMPARISON CHART” a bar graph compares the air flow of the K&N filter and a paper filter. This same bar graph is found on K&N filter boxes. It shows that a K&N filter is capable of flowing 441cfm and an “average disposable after-market air filter” can only flow 319cfm. The impression many may take from this kind of advertising is that you will get a nearly 40% increase in airflow by using a K&N. In reality, this kind of data is essentially meaningless. This data was derived from a flow bench at a relatively low 1.5 inches of water restriction. There is no practical significance to this kind of data. The impression is that a paper filter is starving your engine of air. The reality is that there is no kind of performance demands on any engine or air filter at a mere 1.5 inches of water restriction. The reality is that this kind of data is trivial and misleading. However, K&N is NOT the only company using this kind of marketing. I have seen this same type of data on competitors boxes also. It may be a matter of “play the game or get run over by the competition”, but it is misleading none the less.

Should I Use K&N Filters

This is a question that requires a person to ask themselves just one question. That question is “What is important to me?” A filter is supposed to do three things. Stop the dirt, hold the dirt, and do so while still delivering the air that the engine needs. Making a filter requires careful attention to all of these requirements. However, making a filter is like making a pie.

Imagine making a pie that MUST contain three pieces or slices. The slices are efficiency, air flow, and dirt holding capacity. The trouble the pie maker will quickly learn is that in order to make one part of the pie bigger, another must first be made smaller. Air filters made with superior efficiency in mind will inevitably give something up in airflow potential. A filter designed for performance and airflow will similarly give something up in efficiency and/or dirt holding capacity. It is an inevitable balancing act that all filter manufacturers face. So a consumer needs to know what he wants. Do you want the best possible protection from dirt for your vehicle? Then you should probably go for the OE paper filter. Keep in mind that a lot of cheaper paper filters do not have the efficiencies exhibited by the more pricey OE paper filters. On the other hand, if you are into modifications and like to race from stoplight to stoplight, or from the tree to the line at the quarter mile, get a high flow performance filter. Do you drive in extreme dust? Then go to the next level and make your pie bigger. Go for an oversized, high efficiency, extra high capacity filter designed for your vehicle in extreme dust conditions. Do you want to save the landfills? Then buy a K&N or other reusable type of filter that will last the lifetime of your car and service it as required by the manufacturer.

I was happy to see that K&N understands their niche in the after-market world. Their focus is in their name. K&N Performance Air Filters. They chose air flow as the primary ingredient in their pie and they have balanced that with what they feel is still an acceptable level of filtering efficiency. It was refreshing to see that they understand the give and take in making a filter. No drop-in replacement filter currently on the market can offer the best of everything. Be wary of any company that claims that they can.

Thanks To K&N

I would like to now thank K&N for inviting me out to their facility. They were a hospitable, fun, hard working and dedicated team. They worked hard to answer my questions and were fair and honest in all of our discussions. I found the experience to be enlightening and hope that many will benefit from this report.
 

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Fantastic

Very informative... and detailed.

Thanks "Bunches"

I see you also have "Spell Check"... :exactly:
 

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Wow that is a good write up, and thank you for your time on this.
 

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That certainly was a mouthful, very interesting, thanks;)
 

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Great job Spicer! I understand exactly what you saying! :bow:
 

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THX, Spicer, for all your work, study and dedication on this important part of the choices we must make in the parts we use in the maintenance of our trucks. The effort you have put into this is greatly appreciated by me, and I'm sure, all the rest of the regulars here on the Diesel Place.
Having been involved with motor vehicles that ranged in air filters from none to oil wetted steel wool, to oil bath, to paper, to oil wetted gauze, and oil wetted foam, I've dealt with them all, and many of them in what I consider the ultimate test of an air filter, dirt oval racing. All have their shortcomings and all have at least one advantage.
Just depends, as you so aptly put it, on which slice of the pie you want. For myself, I'm gonna stay with paper, and I do wish that somehow we could get an independent evaluation of the new Amsoil/Donaldson "nanofiber" paper filter.
As you can see, as time marches on, so does "progress" and marketing and all any of us can do is try to absorb all the data we can get, and then evaluate for ourselves according to our "pie" preferences.
THX again,
Dave
 

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Now that , my friends, is some top notch info. Kudos to K&N for going the extra mile to show the "average Joe" consumer what they are all about. I can only applaud them for their efforts. I'd also like to thank Spicer for all the hard work and dedication put into these fair studies. This is top notch work from a top notch person. Way to go!

I have an AFE stage 2 for my Dmax. It is currently sitting on the floor in my garage. I'm thinking a K&N drop in is in my near future. Any company willing to do this sort of explaining to a consumer will get my business!! Companies like this are few and far between. I have seen a few in the Diesel tuning market and that is what got me hooked on Diesels in the first place. Thanks again!
 

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YOU ARE THE MYTHBUSTER! I hate smoke and mirrors with such a passion, I am so glad to see this. And also glad to see that the classic red carpet lubrication attempt failed again. Let's face it, you GOT THEIR ATTENTION!!!!!

YEE HAA!

Anyone who wants to see real filtration, need only take the stock element, remove the pleats, and you can carpet the stairway with it. By contrast, I have a hard time making a useful sponge out of that other crap.

Good going man!
 

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I am amazed at how unbiased the information you provided was, seeing as you were in their facility. Very Nice....
 

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Good effort. well done!
 

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Spicer, well done. If you look at the current Diesel Power Magazine you will see an article on our PowerLoader III tunes for an LLY. Take a look at what happened to performance when we removed and OEM paper filter with 29,000 miles on it and replaced it with a cotton gauze drop in replacement. I think I will stay with the factory paper filter in Duramax applications as the cotton gauze showed little to no gain over a filthy paper unit. I would rather not take a chance when it doesn't gain you anything in this application.
 

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I agree with Killerbee!

Under your Avatar it should say "MYTHBUSTER"

Great job and thankyou.
 

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Very interesting.
Thank you very much for first test results and for this test result.
Still some questions though.
#1: I am not sure if I missed it or not, but are they marketing the 6 layer filter or still using the 4 layer filter that you mentioned at their test facility?
#2: Not a question but a comment. Their marketing hype, even though true, still leads people in the wrong direction/misleading and with reports like this may end up loosing even more customers. The whole idea of having to put literature in a lawyers terms is plain out and out misleading.
#3: Does anyone have anyother idea what may contributing to the MAF sensor issues that so many of have seen? This also is great for a company to take responsibility of somthing that does not even seem to be their problem.
I have K&N filters on my vehicles and have had the MAF issue come up at times. I have never cleaned or replaced and the issue seems to pop up every now and then.
#3: Can you push too much air into these trucks that may set off the MAF sensor code?

Once again thanks for these results.
 

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Has anyone tried the PPE intake for the dmax? It is supposed to come with a larger Donaldson Paper element. This could be just the ticket, Larger area = less restriction and Paper element = good filter efficientcy. What do you guys think? May still need a cold air mod though.

Thanks to Spicer and all who work so hard to gather information and share it with others here.

Absolute
 

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Discussion Starter #16
akdiesel, K&N primarily uses a 4 layer gauze filter for most applications. However, they use a 6 layer gauze for the Duramax, Cummins, and probably other diesel applications. They say they use the 6 layer because the diesels require a higher level of dirt filtration. When I asked for the numbers, in other words, how much higher of a level of filtration, thay said they did not know. I have heard it said many times that diesels need better filtration because of the turbo blades and very tight tollerances. I could never find a minimum efficiency requirement though. If you look at the efficiency of the stock filter you might get an idea. The stock filter is built to a spec. Given the fact that no aftermarket filter gives a stock truck any boost, I will use nothing less than the OE filtering efficiency.

I don't think you can PUSH too much air into our truck and set off a code. The turbo dictates the airflow.

AbsoluteGMC, I do not know about the PPE, but UMP (United Metal Products) makes a filter box for our truck that uses an oversized Donaldson paper filter. I am sure it is a great product and may very well surpass the OE in a lot of categories. On that note, have you seen the new '06 airbox and filter? It is a freaky looking honeycomb filter made by ACDelco with Donaldson media. The airbox also has a cyclone action intake that separates some of the dust before it enters the filter media. Looks awesome, no idea on exact numbers.

I have done some research on the Amsoil/Donaldson nanofiber and it seems that it could also be an improvement over the OE. I think we may be on the horizon of some really innovative technology that could finally catapult us out of the current air filter dark ages. SPICER
 

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have you seen the new '06 airbox and filter? It is a freaky looking honeycomb filter made by ACDelco with Donaldson media. The airbox also has a cyclone action intake that separates some of the dust before it enters the filter media.
My take on it. Was to keep heavy's (water intrusion) from taking hold as in some of the 01 issues dealt with. Spin, and gravity ejection out the bottom. Would love to see a film clip of that in a rain storm.
 

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awsome info. in all the testing you have done, was there really a huge difference, or were they all pretty close? and when i say pretty close, a 70% or higher would get me to the next grade!
 

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thats cool...man my head is spinning now...that didnt help my hangover
 
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