http://shoforum.com/showpost.php?p=349755&postcount=7
I found this on another forum I visit and thought it may be of interest here.
Pics of cotten gauze vs paper under a microscope
- Thread starter olympic
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DOH, sorry about that! I forgot you have to be logged in to view that forum. I'll copy and paste the info here:
As Tom mentioned, I have a microscope that plugs into a USB port and a few years ago I took some up-close pix of a K&N filter, a FRAM paper filter, a shop towel, and a Chipotle napkin (it was handy). Here are some of the results:
First, the K&N. This is a backlit shot at only 60x magnification.
Now a couple front-lit shots, also both at only 60x magnification.
I had difficulty focusing on the paper filter because of the tight pleats. Here are shots at 200x and 60x (in that order). Both are top-lit because they blocked too much light to get a shot when backlit. I couldn't see any visible holes anywhere at any magnification.
Here's a back-lit shot at 60x magnification of one of the common blue paper shop towels that you can buy at Costco or Wal-Mart:
I've got a lot more shots of BIG holes in the K&N filter. They're the norm, not the exception. You have to really search for places that don't have these big holes. It's just cotton gauze, after all. Just looking at the pix it seems like you'd be just as well off using a single shop towel as a K&N filter.
The reputable independent studies that I've seen have all come to the same concusions: The K&Ns flow marginally better when they're clean since they don't filter very well, and once they're dust-loaded they filter about the same as a paper filter and also flow about the same. So you get a very marginal increase in flow while it's not filtering well, and equivalence to a paper filter when it's dirty. Many dyno test, including with SHOs, have consistently indicated very small differences in HP between no filter at all and a paper filter.
I don't normally jump in on product opinion unless I think there are some really significant points, but this is one of those cases. Many people who consider these are on reasonably tight budgets. It just bugs me to see people part with cash for something that potentially shortens the life of their engine and provides little to no performance benefit.
Right now there's a cotton gauze cone filter on my SVTFocus. I've been searching around for a paper substitute that will fit on the aftermarket short ram intake that was on the car when I bought it. If I can't find something that fits I'll try to scrounge up a stock airbox and retrofit it so that I can use paper filters. I plan to drive this car a while.
Now a couple front-lit shots, also both at only 60x magnification.
I had difficulty focusing on the paper filter because of the tight pleats. Here are shots at 200x and 60x (in that order). Both are top-lit because they blocked too much light to get a shot when backlit. I couldn't see any visible holes anywhere at any magnification.
Here's a back-lit shot at 60x magnification of one of the common blue paper shop towels that you can buy at Costco or Wal-Mart:
I've got a lot more shots of BIG holes in the K&N filter. They're the norm, not the exception. You have to really search for places that don't have these big holes. It's just cotton gauze, after all. Just looking at the pix it seems like you'd be just as well off using a single shop towel as a K&N filter.
The reputable independent studies that I've seen have all come to the same concusions: The K&Ns flow marginally better when they're clean since they don't filter very well, and once they're dust-loaded they filter about the same as a paper filter and also flow about the same. So you get a very marginal increase in flow while it's not filtering well, and equivalence to a paper filter when it's dirty. Many dyno test, including with SHOs, have consistently indicated very small differences in HP between no filter at all and a paper filter.
I don't normally jump in on product opinion unless I think there are some really significant points, but this is one of those cases. Many people who consider these are on reasonably tight budgets. It just bugs me to see people part with cash for something that potentially shortens the life of their engine and provides little to no performance benefit.
Right now there's a cotton gauze cone filter on my SVTFocus. I've been searching around for a paper substitute that will fit on the aftermarket short ram intake that was on the car when I bought it. If I can't find something that fits I'll try to scrounge up a stock airbox and retrofit it so that I can use paper filters. I plan to drive this car a while.Very interesting. I'll stick with my Wix paper filters.
Patman
Staff member
My Corvette came with a K&N air filter already installed by it's previous owner, and I decided to leave it in for at least one UOA to see how it performed.
I inspected it when I put in the Z06 airbox, and it looked very new as well. But yet in my first 5000 mile interval my silicon was only 7ppm!
I too used to worry that a K&N would let too much dirt into my engine, but in my case it is obviously working very well.
I will switch to a paper one when this one reaches the end of it's life though, I don't plan on cleaning it.
Patman, do you think that might have more to do with your area then the filter. Silicon is usually read as dirt, but obviously dirt can be a lot of things, perhaps your area does not have a lot of silicon to ingest. Also air intake design may be a big factor. Where does your Corvette draw it's air from? I know a lot of Grand Prix guys like to put their K&Ns in the fender. I'd be willing to bet their a lot more susceptible to dirt then most air intake setups.
-T
Patman
Staff member
It is definitely possible that the design of the intake for my Corvette is largely responsible for the good silicon readings. It does use a large filter, plus it doesn't have a direct flow of air into the filter, although I did cut open the front of the airlid for better flow. But that airlid is also blocked by the nose of the car, so air has to kind of swirl around under there to get to the airbox.
1000 micron air filter? That's why I removed the cotton gauze air filter I installed on my car. I just didn't have confidence in it.
olympic, thanks for the pictures. Seeing the holes may help some "see the light". I agree 100%. It really bothers me to see well intending consumers get scammed. There are 2 things I despise. Liars and thiefs. K&N feeds us misleading info (the lie) and uses that info to coerce us into parting with our money (the theft). This is the motivation behind my air filter study. Thanks for the post. SPICER
Great information on cotton gauze material versus paper filter medium. I was wondering if you have any information regarding Green Filters? Evidently they use cotton material versus gauze.
http://www.greenfilterusa.com/default.asp
Any information you can share on this type of filter would be appreciated.
Thanks.
The pics and info are not mine, I ran across them in a random thread on another site I visit. So I don't have any info on the Green Filters.
How does that oil K&n compair to a stock cotton Toyota filter? I've been running toyota filters thinking I was doing the very best for my truck.
Than is Why we don't see gauze filters on tractors ,Trucks etc.
quote:You might want to look into the Apexi Power Intake Filter which did very well in this test: http://mkiv.com/techarticles/filters_test/2/index.html More info here: http://mkiv.com/techarticles/filters_test/1/index.html
Originally posted by olympic: I've been searching around for a paper substitute that will fit on the aftermarket short ram intake that was on the car when I bought it. If I can't find something that fits I'll try to scrounge up a stock airbox and retrofit it so that I can use paper filters. I plan to drive this car a while.
AndyH, There is one test and one test only that is internationally recognized as THE test for judging air filter performance. That test is the ISO 5011. This is the old SAE J726. The ISO is the International Standards Organization. The ISO 5011 is an unbiased, straight foreward, 100% repeatable test that is THE exclusive test throughout the air filtering industry. Any air filter manufacturer that uses their "own test" in order to show you their filtering superiority is simply "avoiding" the truth that would be revealed in the "real" test, the ISO 5011. I wouldn't touch a filter represented by a made up in house test with a 10 foot pole. Call them and ask them for the ISO 5011 test data on their filter. If they DO send it to you, it will probably be only a portion of the test, such as the airflow portion. Even K&N will brag about their performance in the ISO 5011/SAE J726 with regards to AIR FLOW ONLY! However, the test ALSO tests for dirt filtering efficiency and dirt holding capacity. K&N won't share THIS data even if you hold a gun to their heads. Why? because they are CRAP at filtering dirt. Great at air flow, but will keep out the bricks and birds and that is about it. I am sure these filters you linked us to are equally crap at filtering dirt. Do not be deceived. If you have not read our air filter study, do so. Just trying to protect my friends from being ripped off. SPICER
Here it is:
http://kmoore.phzero.net:8081/digital/1/converted/napa_6440.jpg
Napa Gold FIL-6440. This is the "light duty" version. The "heavy duty" version is the FIL-6441 and has a 3/4" larger diameter. In order to fit the 6441 I'd have to relocate my charcoal canister somewhere else.
It replaced this:
http://kmoore.phzero.net:8081/digital/1/converted/dirty_K_N.jpg
I expect the new filter is doing a WAY better job filtering my intake air and it is most likely no more restrictive. Maybe even less?!
I did take more pics of the K&N if anyone is interested.
I pulled out my disgusting K&N cone and replaced it with a big paper cylinder for a 99 Chevy 2500 350 (the light duty version). I slipped it over the big diameter part of a 45* PVC elbow. Tight fit. I also bought some GE Silicone II black that I may or may not use.
The K&N had been in there since 2001 and was disgusting. I have actually cleaned and re-oiled it at least twice, maybe 3 times. It had a few pin holes and probably abused my engine with dirty air. At least now I have a nice paper filter with a lot of media (a lot more surface area than the K&N had). Went with a Napa Gold for the application above (6440, IIRC).
Pics are coming.
quote:My motorhome had a great UOA on a K&N. Silicon was 3 ppm. Nonetheless, I don't like the K&N when it is time to reoil. I tried reoiling one for my pickup and ended up getting about 10 times too much oil and couldn't use it. I kept oiling it because when I would hold it to a light I would still see holes like in the photographs above. I abandoned the K$N in two vehicles now and went back to paper. When the motorhome K&N gets dirty enough, it likely will go paper too. Also, washing it is a pain. Where do you dump the oily water? They should have a service where you can turn it in for a reoiled one. At least you can inspect them for holes in the store.
Originally posted by Patman: My Corvette came with a K&N air filter already installed by it's previous owner, and I decided to leave it in for at least one UOA to see how it performed. I inspected it when I put in the Z06 airbox, and it looked very new as well. But yet in my first 5000 mile interval my silicon was only 7ppm!
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