I have read this test results before, and our good friend Off Road Teacher brought it back to my attention in a recent post (thanks Teacher). I wanted to open it up for discussion, and get everyones thoughts on it.

http://www.duramax-diesel.com/spicer/index.htm

Clearly, a lot of money and effort was put into this test, but are the results really as dramatic as they appear. I'm not saying this study isn't useful, I just hate to see people jump to conclusions based on information that is not necessarily accurate or relevant.

Some of my observations:

-The graphs are a little misleading. For example, the first graph displaying Filter Efficiency makes K&N for example appear to be far behind the other filters. In reality, if you read the numbers, K&N is still 96.8% efficient, a difference of just over 3% from the top performer. This is not much difference, but a quick glance at the graph leads you to believe otherwise.

-What this test fails to provide is what the acceptable levels of filter efficiency, dirt passed, and accumulative gain are before you actually have a problem. In other words, yes, some filters allowed a higher percentage of material through the filter, but is that necessarily an issue? Does anyone know what the exceptable level is? Who cares if one filter allows 7.9gms of material through if the acceptable level is something like 15 gms. Without knowing the acceptable level, you do not know if the test results are good or bad. Spicer admits himself that he does not know how much is to much when he says "Now how much is a lot? ANY MORE THAN NECESSARY is TOO MUCH! " True, but still, my questions is how much is more then necessary.

-I disagree with Spicers statement "The stock filter will flow MORE THAN ENOUGH AIR to give you ALL THE HORSEPOWER the engine has to give." If this were true, then he is essentially saying that a stock engine produces as much horsepower as it can ever produce, and programmers would be useless. You can clearly demostrate that increasing air and increasing fuel produces more horsepower in the same engine. If I increases fuel with my stock filter, I would run rich because I do not have enough air, so clearly my stock filter is not flowing more then enough air.

Anyway, I am not deliberatly defending K&N. I would love to know what the best filter is for airflow and dirt protection. I am just not sure this test gives that result. Tell me what you all think.

 

I look at it in terms of price. Why would I pay all that money for a K&N filter when it performs at or below the level of the other filters in the tests? I am not saying that the K&N performed poorly, just that if I am going to pay the extra money for a K&N I expect to receive superior performance over other filters. The test results clearly show that the K&N did not perform better than the other filters, but in fact performed worse than most of the other filters. Based on the results of the tests in the study, I find myself hard pressed to justify the cost of a K&N filter over a comparable filter.

 

I agree with you Teacher about price, but filter performance can be several things since a filter performs more then one function. Dirt capture performance and air flow performance are 2 different functions of an air filter. K&N showed much better ability to flow air (see Restriction to Flow chart). If that is ones goal, then it is in fact a superior filter. If dirt capture is ones primary goal, them agreed, it is not superior. Not sure if there is a filter that exists today that is superior at both, so it is a trade off based on what your primary goal is for a filter.

This comes back to my main point about this test. Just because one does not perform as well as others in one area (like dirt capture) does not necessarily mean that it does not perform well enough. Someone needs to define what "well enough" is before saying a filter does not perform adequately.

 

One comment I can make about the K&N filters, I have used them on my trucks for a long time with no problems. However, I have a 4-wheeler with a K&N, and you have to make sure that the filter is properly oiled before riding in usual 4-wheeler conditions. (dust, dirt, sand, mud, etc.) The rings went bad in mine, the shop told me it was due to the K&N not being oiled consistently, and that they had had a lot of ring jobs due to this. I remove, clean, and reoil my K&N in my truck about every 15k miles instead of the recommended 50k now. I read the test on here, and I have a hard time believing that a paper filter is better, all things considered. Just thought I'd provide that for input.

 

I have heard about situations similar to what Racinfan83 describes where there has been excessive engine wear as a result of particle passing through a K&N filter. I would gladly sacrifice one or two hp due to less air flow in order to save my engine from possible damage due to dirt getting through the filter. But that is just my way of looking at it, I am certain that some people are willing to take that chance in order to get better air flow. A couple of hp are not worth that to me.

 

Does anyone make a cone style filter (similar in shape to your average K&N filter) made from conventional filter paper, or do you pretty much have to use the stock air hat to use a paper filter?

Also, has anyone seen any other filter studies that confirm the results of this study? I know I won't find them on the K&N website.

 

I know you can one through Autozone and Pep Boys that is a cone style and made or paper. It is made by Fram, runs about $10. However, it is not for a Dodge, it is off of a 1995 Ford Explorer. It just happened that I was visiting my parents one day and decided to help my dad work on my mom's explorer. When he opened the hood, I saw the factory air tube with a cone at the end. So I took it off to measure and it will fit on a 3" to 3 1/2" tube, just the size I need when I go to get a new filter. But, it may be some work to make it fit exactly right.

 

The ISO 5011 filter study is an impressive piece of work.
You will not find many studies that complete.

One problem is most people don't know how to read the graphs.

They use inches of water pressure (in H2O) in their restrictions.

Keep in mind that 14.7 psi is about 402 inches of water and also about 30 inches of Mercury (Hg)

So when you read that a filter is causing about 4 inches of H2O restriction that means it is hurting your 4000-5000 rpm maximum horsepower about 1% (4/402)

The graphs also show that at low rpm and modest air flows
the restrictions are even lower
and don't have nearly any effect on 'day to day' part throttle engine power.
zip nada nothing (and no mpg benefit either)

It would have been better if the restrictions had been in inches of Hg or the metric kPA because that is what a diagnostic OBD-II scanner will tell you about your Ram engine's MAP sensor (manifold absolute pressure) With a scanner you can easily find out for yourself "in the real world" what kind of pressure reductions different brand filters can give.

Is a filter that removes 99.93% of the particles in a test
all that much better than a filter that removes 96.80% ?

Yes - if you are a mining engineer like me that has been responsable for the cost and durability of a fleet of haulback trucks, bulldozers and pans with V12 and V16 diesel engines that require $40,000 to $75,000 to rebuild. The quality of a $15-40 air filter is very important for cost versus benefit ! It is even more important when this equipment sometimes operates in very dusty road conditions, where the concentration of dust is grams/cubic meter and the number of particles is millions per cubic foot.

Does it matter to a typical Ram truck owner who intends to trade off his pickup when it has less than 100,000 miles?
Probably not.

Does it matter to a non-typical Ram truck owner like me who now has now put 180,000 miles on the original 1995 Magnum 5.9V8 and 46RH auto ?
Yes.

At the KN website they have certified results from independent laboratories showing their low restriction filters do provide a slight HP increase. The ISO 5011 results tend to confirm this.

 

I'd like to see more testing done, by more people/labs. And some correlation between dirty/clean filters and gas milage differences.

 

HankL,

I always respect your thoughts on things and I appreciate your input, but my question still remains.
It appears to me that any test can tell me that one filter is n% better then another filter, but does anyone know what % difference is were you cross into bad things happening to your engine? How do we know that you couldn't have put 180000 miles on your truck with a filter that was 96.80% efficient (instead of the one that you have that is 99.93% efficient). How do we know you couldn't have done that with 93% efficiency or 90% efficiency either. I guess I would like to see the study that says how each percentage decrease in filter efficiency affects your engine in terms of measurable deposit buildup, degredated engine life, etc...

I guess if I can put 180000 miles on my truck with a filter that is 3% less effective at dirt protection then the best filter, but flows n% more air to increase performance, then that is the filter I want to be using. This study does not disprove the ability to do this for me.