It is such a simple, yet inspiring credo, used by at least one filter marketing campaign. It is hard to fathom that this simple statement could be so abused…that the simple “truth about filters” could be so ripe with moral and ethical controversy.
Warning: Myth busting in progress. Don’t hate me! I find the assault of aftermarket intakes on the turbo-diesel crowd to be an ethical epidemic of utterly putrid proportions, one of the great all time cons. The myth is that the vehicle manufacturer bobbles the intake so frequently that you need a new, improved, redesigned, better flowing intake to moo-ve more air, blah blah…you get the idea, put your stock intake to pasture.
Over and over I see folks steered this way despite the reality that there is absolutely no beefy performance advantage at steak. The promises of fat trimming performance increases abound in a field ripe with ignorance. Reality? Find and milk a flying cow, its more productive than the belief that the OE intake engineer doesn’t know what he is doing. In most cases that is… a hot air ballon.
This article was created to keep you from being prey to lies, marketing deception and slight of hand, and ultimately, to help you to sort through a jungle of smoky marketing claims. It offends me that this article is even necessary, but for the consumer, this is my way of keeping the aftermarket performance world 98% “smoke free”.
THE PLACEBO EFFECT
The definition originated in medical circles: "The physician's belief in the treatment and the patient's faith in the physician exert a mutually reinforcing effect; the result is a powerful remedy that is almost guaranteed to produce an improvement and sometimes a cure." -- Petr Skrabanek and James McCormick, Follies and Fallacies in Medicine, p. 13.
Since originally studied, it has been applied to many walks of psychology, including staffed corporate marketing departments, who have refined it a bit. Simply put, marketers know that if they can create an expectation in the mind of their customer, and then not do anything to contradict that expectation, they have a good chance that the customer will find that expectation to be fully met. The “not contradicting” element is a key part of the process.
Also known as the power of suggestion, this widespread observable phenom is responsible for many interesting miracles. People heal quicker, run faster, see sharper and even learn at a faster rate, all with only the belief that an improvement has been bestowed. Plus it only works on humans and doesn’t work on cars, trains, robots or turnips. Why? Because we are the only creatures with enough intelligence to buy into it. We can think, reason, and that can be a dangerous thing, as the Darwin Awards annually, and perpetually confirm.
We, as an intellectual race, still have no rational explanation why we can will ourselves healthy, for example, after swallowing nothing more than cleverly marked sugar pill, administered as the widely hyped cure.
How is it done in the aftermarket world? Package a smart (looking) product in a colorful box, with universal, yet ambiguous and non-specific claims printed all over it, then add a significant, yet affordable price tag. After all, “who would charge so much for something that doesn’t work?”. Or better, “who would pay for something that doesn’t work?” Well the placebo industry is alive and well, proving that too many folks do. Is this a scam? You need to decide that. Some statements will get me into hot water, and truth has very little to do with litigation outcomes in this country, unfortunately.
If I was creative in trying to sell the public, I would make it different, of course, say with a “4-6 layer oiled gauze media”. To make this plan even more effective, make it a DIY project. No way we can admit that our own effort and expense can bring about, hmmmm… “nothing”. In fact, study after study has proven that when a ritual is added to the placebo treatment, the study subjects experience even more pronounced placebo benefits of the treatment. I would think then, the harder you work to install your intake, the more impressive the end result, a dizzying concept. Topping it off, what if cleaning and oil servicing were required and coincidentally aligned on the vehicles oil change interval (recurrent placebo training…).
EGO-sta-TISTICS
It’s just too funny. Have you ever seen a more egotistical crowd than vehicle enthusiasts? A La Leche convention perhaps? Perhaps lactating vegetarian moms have a marketable product and an intellectual edge, despite being the neighborhood hangout for 3rd graders. At least they see a child grow from their efforts. It is one organization likely to appreciate one grounded advantage of a serviceable filter: it is a landfill-friendly alternative.
Naturally, as an egotistical male seeking a performance edge, you research. Jump on the forums, do Google searches, question the beer fisting, greasy CTD owner up the street, and your toothless brother-in-law mechanic in Mobile. Naturally you come across some proud owners of “XYZ intakes”, who inevitably claim a mild but obvious improvement to performance or economy, right? “Count me in!” So you order one, and set yourself up to become the next domino in the big plan. Remember, you are the proud new intake owner, now positioned for the best kind of advertising there is…the free kind. Who needs beer to work on cars, expressing milk has never been easier.
Cole only learns later, in victory lane, that the whole tire thing was just a placebo ploy by his crew chief. There is study after study on this, and they all say the same thing: If you make a significant effort, and/or expense, to obtain an expected result, you may actually realize some manifestation of that result, even if it is factually non-existent with instrumentation. We are suddenly able to perform just a little better at the chosen task, be that NASCAR driving or that 66th hot dog. If you truly believe, through the placebo lure, that your car is better, “you CAN hold it”, though instrumented proof to the contrary denies even the remote possibility of a measurably improved state.
Obviously I don’t romance my intake, ego checked at the door. But if, by chance you are still reading this article, if only to see what this idiot is going to say next, I have around 40 hours of data logging with various aftermarket intakes, plus my own stock intake, and another 200 hours of optimization work, an engineering degree, and lotsa common sense. I have a pretty good idea about this. The science is not all that complicated; there is no lab derived secret formula to effective intake efficiency. Contrary to colorful bragging, there is no need for a “1/2 million dollar, climate controlled lab” or a crew of key punching white suits; It only takes a modest understanding of fluid flow, and a $15 pressure gauge to be considered competent on “the truth about filters”.
NUMBERS DON’T LIE
Someone else already did the footwork in what I consider one of the most enlightening and myth busting studies on this topic; introducing Arlen Spicer. It was a real awakening, and he gets all the credit for being inspired to seek truth, safely out of the grips of the aftermarket industry. His ISO 5011 standard study is a well controlled, professionally administered comparison of a number of replacement elements for the Duramax stock air intake. They all claim to be the best filtering, least restrictive, best power producing alternative.
If you would like to explore the whole study, you can see it at http://duramax-diesel.com/spicer/index.htm.
The factors that were analyzed ranged from resistance, to dirt holding capacity, to filtration efficiency. Take note also, this is NOT in-house testing; it is independently monitored 3rd party data. No conflicts of interest here.
With respect to oem replacement elements, he writes,
“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 XX # 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. …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?
Now, while it is a well documented and thorough gift to the consumer, even a seemingly black and white test can be subject to interpretation. I have my own opinion, and some points that are not self-evident. Some of the original data is reprinted here with permission:
An important aspect of filtration is the capture effectiveness. A filter, after all…should filter. In this chart the filtration efficiency shows the fraction of dirt that is captured by each. Testing determined that the stock AC Delco element captures 99.93% of the dirt particles, while the bottom contender captures 96.80%. Seems acceptable? How significant can it be, after all, to allow only 3% to get by? I don’t know…how much asbestos are you willing to let your children breath?
If you look at this another way, and substitute real numbers in, it might have more meaning. For every 10,000 particles of dirt dosed, the Delco element catches all but 7. The KN catches all but…320, only a 4500% increase! Does that mean a wear rate increase of 45 times? Well…sort of. The wear rate due to dirt ingestion, should, logically be magnified the same amount. The OEM engineers could easily have provided this level of filtration, and didn’t, so you decide. They paid for better, and GM doesn’t pay for something it doesn’t need. They know that longevity hinges on many things, and clean combustion air is not the least of these. Clean air reduces compressor blade pitting, decreases oil soiling, increases oil filter life, reduces cylinder and valve wear, preserves MAF sensor function, and probably a half dozen other essential benefits. There is 800,000 lbs of suspended abrasives floating in every cubic mile of urban air. You have cause to be concerned, despite numerous marketing statements to the contrary. This is not the kind of wear that shows up next week, or even next year. It is the kind that can be measured over 50,000 miles, the kind that can turn a 300,000 mile motor into a 150,000 mile motor. If you plan to trade up next year, then you don’t need to care. But if you measure your own business success by keeping overhaul costs down, this is important.
A $25 engineered high capacity filter element is not the place to cut costs, when thinking a $50 “lifetime serviceable” alternative is saving you money in the long term… It’s not! I’ll prove it.
INTAKE RESISTANCE=LOST PERFORMANCE
Efficiency is how good the element is at stopping dirt. An immutable principle when using the same filtration media, is that efficiency and resistance to flow are mutually exclusive. Keeping filtration area the same, you can’t improve one without hurting the other. Ultimately, element performance is a compromise of 2 physical properties: surface area and media porosity. These, in combination with the desired airflow rate, pretty much define resistance to flow.
The turbo is a just a centrifugal air pump, and all centrifugal type pumps have flow rates that are very sensitive to restriction. Big restrictions in the plumbing will severely reduce the air quantity ejected from the compressor. This a real problem…and one that is manipulated highly for marketing purposes…read on.
We have all read the statement, “more air in, more air out”, in describing the performance requirement for better diesel intakes and exhausts. And it is true, but only IF there is a significant area of deficiency to improve upon. Don’t tell the intake companies but this is just not always the case. Resistance to flow is the focus of these claimed improvements. Eliminating this “negative boost” is the goal. It is typically measured in inches water column, or iwc. 1 psi is equal to 28 iwc. “How much resistance should we care about? How much is enough to cause a perceptible change in performance? 5 inches? 10 inches? 2… psi?” On a turbo diesel Duramax, I experimentally concluded that 20-25 iwc, around 1 psi, is the restriction I must add to feel any performance reduction from the drivers seat, albeit a subjective determination. Experimentally, this also works out to about 2-3% less airflow.
We must concede that we endeavor for the least restriction possible. Like dirt, and as Arlen agrees, “Any more than necessary is too much!”. Realizing that we need to eliminate 25 iwc of restriction to realize any tactile improvement, let’s now look at his 3rd party verified data, and remember, he had no company profile to protect, or corporate bottom line to look after.
Very Impressive! KN clearly looks to be the clear restriction frontrunner. “A no-brainer”?
I quickly notice something that concerns me. As a nerdy engineer, I get suspicious whenever the Y-axis does not begin at zero. It can be suggestive that someone has gotten… “creative”: So if we rescale this chart along a full scale axis that shows a 25 iwc (performance threshold) of perceptible performance, the story becomes pictorially more revealing of some otherwise disguised realities. (This is the part I dig…the real “truth”.)
The checkered short bars represent the same exact data as that appears in the first chart, only this time on a full scale y-axis. Does this picture convey the same message now? The hi-low range of restriction still spans 3 iwc. I went a step further, the taller bars represent restriction of these elements at 700 cfm, stock boost, full throttle conditions. If a change of 25 iwc represents a significant improvement, clearly there will be no apparent improvement from ANY of these candidates. This holds true within a range of 1-2 HP on a dyno.
Insignificant data, through slight of hand, can look dramatic. Arlen had no intention of being deceptive, and that first chart was not intended to deceive. Actually he was trying to demonstrate to the contrary. I showed it here as an example of truth bending, smoke and mirrors marketing technique. It reminds me of the milk craze begun back in the early 80’s, specifically the marketing of the new alternative, low fat milk as “99% fat free”. They never tell you that whole milk is already 96% fat free! The added taste in that 3% sure does make for better cookies at bedtime. (yes, I was breastfed as a child, and I admit to being lactose fixated, THERE, IT”S OUT!)
GETTING DIRTY
Ya know, even if I lost this argument, and must concede that every inch of water column is important, it is oddly irrelevant: those charts only show the element condition minutes after leaving the retail wrapper. They are clean, new elements, which ceases to represent reality the moment you get behind another truck on a dirt road. Since I have better things to do with my time, I want an element that I don’t have to baby-sit. How does it perform with some miles on it? In that light, the new element performance tests illustrate a fleeting condition. That’s just me, maybe I want to travel dirt roads for a week, and not worry about bringing a filter cleaning kit with me. With this pursuit, let’s look at the resistance comparison of the element that has been on the vehicle after exposure to a dirty environment.
The chart below is, in my opinion, the most meaningful and represents the elements performance ability over the life of the element. The aftermarket company will never show you a chart like this, even though the ISO tests performed by each manufacturer, reveals all of this data. It’s what they don’t show you that you need to worry about. Well, here it is!
Dirt is dosed into each element at the rate of 9.8 grams per minute, at a steady 350 cfm (350 cfm represents a moderate load, analogous to towing an 8000 lb trailer at a steady highway speed). The test ends when restriction reaches 10 iwc over its start test value. After 350 grams, all but one of the elements has ballistically exceeded the stock elements resistance level. For 3 of these “competitors” the test had to ended only 1/3rd into the total Delco dust dosage, because each became too restricted to continue. Worse, those elements are letting lots more of that dirt into the motor, as shown earlier, AND…you are paying for all these…”benefits”.
Just for reference, that colorful plastic gauge thingy on the air box begins to retract from green to red at 15 iwc. You can see how much dirt it takes to get to that level of restriction. At this level, the Delco element accommodates twice the dirt quantity of the worst half of the contenders.
Subjectively, I am somewhat impressed by the numbers that the Wix element produced, showing minimal resistance for over a half pound of dirt. These tests were conducted at 350 cfm, and are unfortunately lacking in completeness due to this point alone, my only criticism. Fortunately however, high flow resistance levels can be closely predicted, as was done for the 700 cfm restriction bars discussed earlier. Basically, each of the elements follows a similar correlation. If you increase flow rate, the resistance level will increase with the square of flow rate. In other words doubling flow rate yields a resistance level about 4 (2 times 2) times. At 250 grams of dirt, the 7.0 iwc (Wix) and 10.5 iwc (stock) levels become 28 and 42 iwc, a significant difference. Since the Wix appears to perform very well this way, while still providing decent filtering efficiency, it might be considered a practical alternative, particularly in performance applications where airflow is raised further beyond stock levels, say over 1000 cfm. The exponential growth rate of resistance must be considered for these cases.
MEANWHILE, BACK IN THE (MARKETING) JUNGLE…
Here is an actual marketing statement:
“The XYZ 2-Stage Air Filter traps airborne dust with 99% efficiency; it holds an incredible 281 grams of contaminant (that's over half a pound); and it outlasts the competition. It performs two to four times longer than the others. That's why XYZ can confidently recommend a 25,000 mile/1-year service life. And the 2-Stage is actually re-usable, with proper cleaning and re-oiling.”
The same company goes on to gloat about the superior performance of oiled foam, yet oddly, never compare themselves against the stock element. I wonder why not???
It is a fact also, that oiled alternatives are tricky to service correctly, and may contaminate the mass air flow sensor with oil/dust deposits. Many an intake owner has run straight into warranty denial at the vehicle dealer service center. Oh, but fear not, some aftermarket companies have anticipated such events. Here is K&N’s website statement regarding your rights under the Magnuson-Moss Warranty Act:
“If you have encountered a motor vehicle dealer, who has failed and refused to “demonstrate” or prove, as federal law requires, that your K&N air filter necessitated a repair for which warranty coverage has been denied, or a manufacturer, who refuses to perform warranty repairs on your vehicle, merely because you have installed a K&N replacement air filter or based on inaccurate information from your dealer, then we ask that you request that the dealer or manufacturer set forth, in writing, the warranty denial, together with a written statement as to the specific reasons for the denial of warranty repairs, and that you send a copy of this written statement to K&N. We also ask that you direct your dealer and manufacturer to the federal law quoted above. K&N assists consumers in this situation through the K&N Consumer Protection Pledge. For details please go to the K&N website at KNFilters.com or contact our customer service department at 800-858-3333.”
My read? Just get your dealer to document that it is in violation of a federal statute, and then further educate them on this law, widely considered a relatively complicated and worthless piece of legislation by many consumer advocates. (cough, cough) Have you ever noted the service managers expression when you try to teach them how to fix cars? The reaction is often less than obligatory. But that doesn’t matter because it appears that KN is volunteering its legal services to all “victims”. Where can you get that kind of customer service in these times?
When I lived in Kansas, I learned to gauge wind direction before relieving myself. You should carefully measure how much risk you want to assume, and decide for yourself if such statements are well intended efforts to warrant your new product, or something else. You could get wet.
“in STOCK”
So how does the OE element pull off this miraculous compromise of long life, filtration ability and flow characteristics? Simple really…surface area.
If you lay out the 121 pleat delco element, it will measure twice the length of the truck, This is 34 square feet of filtering surface. None of the other test subjects come close.
Here is a look at the Delco element next to the KN element. To equal the SA of the delco element, you would need to unpleat 9 or 10 KN elements.
Caution: It is important to mention, there are 2 or 3 other OEM Delco elements that will fit the pre-06 duramax air box. Use care and don’t use them. They have fewer pleats and un-reinforced construction, subjecting them to suction collapse, it is more obvious when they are side-side.
S&B Intakes is another company that has been making a presence recently. They use the ISO 5011 standard to test their intakes (in house) and replacement elements, and they even publish the results, or at least SOME of the results. Here is one of them
http://www.sbfilters.com/pdf/iso_5011_1 ... 5006-1.pdf
In it you will find the statement:
“S&B Filters Part Number 75-5006-1 Flows 52.2% Better Than the OE Induction System at rated CFM”.
“Hmmm? Cooooool!”
My simple take on this statement, on first glance, was that I could reap a 52% benefit in airflow with this intake. (and English isn’t even my second language) Oooh, better than beating photo-radar in court! Does this mean I can get rid of my turbocharger? After my eyes stopped spinning, I went in search of what this statement is based on. Intuitively, and beyond my sarcasm, I knew this was not true. What I found was that the resistance level of the new S&B intake at 609 cfm rated flow (inaccurate by the way), was roughly half that of the OE intake. And… I can accept that, at least among brand new, clean elements. They obviously chose to market this with the above captioned statement, cross-pollinating airflow concepts as though there is “truth” in it. The words to that old song hold true. “nothing from nothing leaves nothing”. If 17 iwc does not hamper performance in a measurable way, is 8 iwc going to restore something that has not been lost? And remember, this is a snapshot comparison of new equipment, which expires the moment the vehicle begins running dirty air through it. Notice that they don’t divulge comparisons of the resistance level through the lifecycle of the dust test, showing where the surface area leader inevitably performs better. That would kill sales.
I then went in search for S&B’s justification for all my confusion, hoping for simple semantics confusion, and found this in their FAQ’s section, emphasis added in blue:
How much increase in horsepower should I see from an S&B Performance Intake Kit?
Horsepower can be increased by decreasing the restriction of airflow to the vehicle’s engine. Typically, the OE stock air box and induction tube significantly restrict the airflow. S&B design’s its intake kits to increase the amount of horsepower by 5-10% by
allowing the engine to breather easier.
S&B does not publish horsepower results specific to each part because the majority of our competition makes outrageous horsepower claims that are unsupportable and often are accompanied by the disclaimer "Up To, As Much As or Results May Vary." There is no standard for dyno testing; therefore, it is difficult to hold our competition accountable for their inflated claims.
S&B utilizes its 1/2 million dollar, climate controlled lab to test its intake kits and filters to the same standard (ISO 5011 Test Standard) used by the OE manufacturers, so there is substance behind S&B's test results.
S&B publishes 2 critical results: airflow & efficiency
1. Airflow Rating: This rating shows how much the filter/intake improves the airflow vs. stock. Improving the airflow results in more power and better fuel economy.
2. Efficiency Rating: Protecting your engine while dramatically improving the airflow is S&B's competitive advantage which is why we post the efficiency numbers along with the airflow rating. The efficiency rating shows how much dirt our filters will stop. Our minimum goal for efficiency is 99.0%.
Somebody is confused, and it’s not you or me. “Airflow” and “airflow resistance” ARE NOT synonymous terms. Cutting element resistance in half DOES NOT double airflow in your intake tract. I can confidently say without hesitation, that a reduction of 7 iwc does not yield a 52% “improvement” in airflow for this, or any other intake or motor. It won’t fetch even a 1% increase in airflow. That is a startling discrepancy! As for the “5-10%” in horsepower… you guessed it…same thing, and anyone can verify this. Now folks…THAT
… is the truth about filters!
Am I saying that an aftermarket element (or entire intake) is foolish in all cases? No. This article does not cover all vehicles or your personal goals. But if there is, in fact, a sky clearing, measurable performance improvement, you must consider that simply removing the bug and nest impregnated factory element may have merely restored your old performance level, which had deteriorated so slowly over time, so as to have gone unnoticed. This happens all the time.
The best marketing in the world is positive word of mouth that costs the company nothing. A proven sales technique is to do nothing and just listen; when you just stay out of the way, often the customer will sell themselves. If you want to sell something in a scam, without lying, just say “some customers report a .5-1.0 mpg improvement in economy”. It is a pathetic state of affairs that many companies are all too eager to take advantage of. The truth is, seldom does your vehicle manufacturer mess this up to the degree that any perceptible improvement can be realized with stock tuning, though admittedly there is an occasional design blunder.
Next, we will cease to beat up the aftermarket industry. Well, sort of, we’ll focus on what they all missed. We will examine an inherent GM intake flaw that delivers negative boost far worse than any restrictive element, describe measurement methods for locating these issues, and tell you what you can do to make a big improvement, where applicable.
BIOGRAPHY: Michael Patton, a degreed Chemical Engineer and SAE member, www.sae.org, specializing in solutions to energy related problems. With 15 years in the aircraft industry, interests lie in servicing difficult challenges that require investigative analysis of heat transfer, fluid mechanics, and thermodynamic issues.
. blah blah. bob, my car is just nearing 300,000 miles, i still drive it everyday....its had cheap fram filters and the cheapest 10w 30 in it since it rolled of the show room floor. who cares 
