Air resistence vs miles or time
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Originally Posted By: finalyzd
So when one of my customers comes in with a filthy air filter its still good? I'm actually doing more harm then good by replacing it? Also in a uoa sometimes blackstone recommends changing the air filter if its dirty? Why? Its filtering better? Also after about 15k miles of driving both the knNs on my car have a layer of black dirt. Are they more efficient when dirty? So many questions wow
Lol. see above posts.
So when one of my customers comes in with a filthy air filter its still good? I'm actually doing more harm then good by replacing it? Also in a uoa sometimes blackstone recommends changing the air filter if its dirty? Why? Its filtering better? Also after about 15k miles of driving both the knNs on my car have a layer of black dirt. Are they more efficient when dirty? So many questions wow
Lol. see above posts.
These aren't the same as for diesel engines are they?
Originally Posted By: bigmike
Originally Posted By: widman
The K&N filter starts at about 85% efficiency and clogs around 98% according to several studies. Some of that, including the 85% is no their site.
A good paper filter is 98-99%, the best paper filters (usually not available for cars) are 99.99%
Our actual air filters when tested generally demonstrate a cumulative filtration efficiency of between 96% and 99%.
So you are stating the above is actually false? Do you believe other manufacturer claims are also false, or just K&N?
They have the 85% somewhere on their site as well. I have a screen shot somewhere on my hard drive and I've seen it in tests on a BMW filter study. (not BMW as a company. A magazine or something).
There are marketing people who print what they think should be printed or can get away with. Happens to a lot of products, like the VW/Cummins study I recently published.
Originally Posted By: widman
The K&N filter starts at about 85% efficiency and clogs around 98% according to several studies. Some of that, including the 85% is no their site.
A good paper filter is 98-99%, the best paper filters (usually not available for cars) are 99.99%
Our actual air filters when tested generally demonstrate a cumulative filtration efficiency of between 96% and 99%.
So you are stating the above is actually false? Do you believe other manufacturer claims are also false, or just K&N?
They have the 85% somewhere on their site as well. I have a screen shot somewhere on my hard drive and I've seen it in tests on a BMW filter study. (not BMW as a company. A magazine or something).
There are marketing people who print what they think should be printed or can get away with. Happens to a lot of products, like the VW/Cummins study I recently published.
Yeah, Widman, I'd like to see something that shows 85 percent on a properly treated K&N. I'm no fan of oiled cotton gauze filters at all, but I've never seen any recent ratings that low. The nearest thing I recall is when someone test an unoiled filter, which was at about 50 percent.
My personal test for oiled cotton gauze filters was to put a smear of grease in the intake tract of a turbo diesel that was four-wheeled in the desert. Took care to make sure the intake was tight. I ran the better part of a season and checked. The grease was gritty. That cured me of the oiled cotton gauze filter. A foam sock pretty much equalizes them with paper from what I can determine but it decreases their holding capacity (you gotta clean the sock fairly often in dirty areas).
My personal test for oiled cotton gauze filters was to put a smear of grease in the intake tract of a turbo diesel that was four-wheeled in the desert. Took care to make sure the intake was tight. I ran the better part of a season and checked. The grease was gritty. That cured me of the oiled cotton gauze filter. A foam sock pretty much equalizes them with paper from what I can determine but it decreases their holding capacity (you gotta clean the sock fairly often in dirty areas).
--Sorry, 96% was on the K&N site, I have a screen shot but they have taken that off their site. The 85% was on the other study.
This is where the interesting study was published, but it is a dead link right now
http://www.bmwe34.net/E34main/Upgrade/Air_filter.htm
But it is referred to with this excerpt (posted on a lot of performance sites as well)
Quote:
Jim Conforti (AKA the Land Shark) did some testing:
This was a scientific test, not one done by filter manufacturer X to show that their filters are better than manufacturer Y. The test results are pretty irrefutable as the test lab tests and designs filters where "screw ups" are absolutely NOT allowable (I can't say any more for security. Think "Glow in the Dark").
A scientific test was done on TEST filters where air was loaded with ACCTD (some standardized "test dust" called AC Coarse Test Dust) and sucked through the TEST filter then through an analysis membrane. From the Quantity of dust injected and the amount that gets through the TEST filter and is then captured on the analysis membrane we can calculate the efficiency of the TEST filter in Question.
BMW Stock Filter, Eff. Area of Media: 8.4 sq ft.
K&N Replacement, Eff. Area of Media: 1.6 sq ft.
The filters are the SAME size._ They both fit in the STOCK BMW M3 airbox._ The difference is that the STOCK filter has 65 pleats 1.5" deep and the K&N only 29 pleats each 0.75" deep.
Now, remember this ratio: " 5.25:1"._ It's the ratio of the AREA of STOCK to K&N._ It's very important and will come into play later.
The STOCK filter efficiency started at 93.4% at 0 loading and increased to 99.2% efficiency as the loading increased to a max tested of 38.8 gm/sq ft of dust.
The K&N filter efficiency started at 85.2% at 0 loading and increased to 98.1% at the max tested loading of 41.38 gm/sq ft.
on this and other pages
BMW filter study
This is where the interesting study was published, but it is a dead link right now
http://www.bmwe34.net/E34main/Upgrade/Air_filter.htm
But it is referred to with this excerpt (posted on a lot of performance sites as well)
Quote:
Jim Conforti (AKA the Land Shark) did some testing:
This was a scientific test, not one done by filter manufacturer X to show that their filters are better than manufacturer Y. The test results are pretty irrefutable as the test lab tests and designs filters where "screw ups" are absolutely NOT allowable (I can't say any more for security. Think "Glow in the Dark").
A scientific test was done on TEST filters where air was loaded with ACCTD (some standardized "test dust" called AC Coarse Test Dust) and sucked through the TEST filter then through an analysis membrane. From the Quantity of dust injected and the amount that gets through the TEST filter and is then captured on the analysis membrane we can calculate the efficiency of the TEST filter in Question.
BMW Stock Filter, Eff. Area of Media: 8.4 sq ft.
K&N Replacement, Eff. Area of Media: 1.6 sq ft.
The filters are the SAME size._ They both fit in the STOCK BMW M3 airbox._ The difference is that the STOCK filter has 65 pleats 1.5" deep and the K&N only 29 pleats each 0.75" deep.
Now, remember this ratio: " 5.25:1"._ It's the ratio of the AREA of STOCK to K&N._ It's very important and will come into play later.
The STOCK filter efficiency started at 93.4% at 0 loading and increased to 99.2% efficiency as the loading increased to a max tested of 38.8 gm/sq ft of dust.
The K&N filter efficiency started at 85.2% at 0 loading and increased to 98.1% at the max tested loading of 41.38 gm/sq ft.
on this and other pages
BMW filter study
But you failed to give K&N's response:
Quote:
K&N Response:
It is incorrect. The difference between 99.2% and 98.1% (his results) is 1.1% not 224% as he states!!! (bmwE34.net: who didn't go to school, Jim was measuring the amount of dust that goes inside the engine). Furthermore, does he realize that 96% meets OEM standards? K&N has been around for over 30 years and we sell over 2,000,000 units a year. If there were any sort of problem, one would think we would know by now and so would everyone else. One Internet "expert's" opinion is not reason for concern and should be taken loosely at best.
That information is 100% untrue. Don't believe all you read on the Net. Most is opinions not based on any sort of factual evidence. Our filters are tested by an outside, independent laboratory. They have been proven to stop at least 99% of particles on a SAE dust test. This test uses particles as low as the 0 - 5 micron range and goes up to 20 microns.
For comparison, a paper filter also stops 99% on the same test and the OEM minimum standard is 96%. Foam is generally the worst media with a typical efficiency rating of 75 - 85%. To get higher ratings, the foam must be more dense and therefore way more restrictive. The "tack" characteristic of a K&N allows for increase filtration without loss of flow as well. The testing procedure used is SAE J-726 using ISO Test Dust.
This test is the standard of the air filter industry. The test procedure consists of flowing air through the filter at a constant rate (airflow rate is determined by the application) while feeding test dust into the air stream at a rate of 1 gram per cubic meter of air.
As the filter loads with dust the pressure drop across the
filter is increased to maintain the prescribed airflow rate. The test is continued until the pressure drop increases 10" H2O above the initial restriction of the clean element (in this case .78" to 10.78" H2O). At this point the test is terminated. The dirty filter element is then weighed. This weight is compared to the clean element weight to determine the total Dust
Capacity. The amount of dust retained by the filter is divided by the total amount of dust fed during the test to determine the Cumulative Efficiency.
The K&N filter achieved the following results:
- Dust Capacity: 305grams
- K&N Cumulative Efficiency: 99.05 %
Now, I'm just like anyone else, typically skeptical of manufacturer claims.
I find it amazing though that people will agree and believe MOST claims, especially numbers (think about wet/dry boiling points of brake fluid, HT/HS or Cst of oil, etc), yet - when it comes from K&N - it's immediately dismissed. Even when they (K&N) claim their results come from an independent lab.
I'm certain that K&N filters do allow more dust than a highly efficient (see: good) paper filter that is properly sealed. Question is, is that percentage more harmful within say, 500k miles?
Jim, that's a good test you did, however unscientific it might be! I think that is something I'll do as well. I figure that climate and condition would matter quite a great deal on the results.
Quote:
K&N Response:
It is incorrect. The difference between 99.2% and 98.1% (his results) is 1.1% not 224% as he states!!! (bmwE34.net: who didn't go to school, Jim was measuring the amount of dust that goes inside the engine). Furthermore, does he realize that 96% meets OEM standards? K&N has been around for over 30 years and we sell over 2,000,000 units a year. If there were any sort of problem, one would think we would know by now and so would everyone else. One Internet "expert's" opinion is not reason for concern and should be taken loosely at best.
That information is 100% untrue. Don't believe all you read on the Net. Most is opinions not based on any sort of factual evidence. Our filters are tested by an outside, independent laboratory. They have been proven to stop at least 99% of particles on a SAE dust test. This test uses particles as low as the 0 - 5 micron range and goes up to 20 microns.
For comparison, a paper filter also stops 99% on the same test and the OEM minimum standard is 96%. Foam is generally the worst media with a typical efficiency rating of 75 - 85%. To get higher ratings, the foam must be more dense and therefore way more restrictive. The "tack" characteristic of a K&N allows for increase filtration without loss of flow as well. The testing procedure used is SAE J-726 using ISO Test Dust.
This test is the standard of the air filter industry. The test procedure consists of flowing air through the filter at a constant rate (airflow rate is determined by the application) while feeding test dust into the air stream at a rate of 1 gram per cubic meter of air.
As the filter loads with dust the pressure drop across the
filter is increased to maintain the prescribed airflow rate. The test is continued until the pressure drop increases 10" H2O above the initial restriction of the clean element (in this case .78" to 10.78" H2O). At this point the test is terminated. The dirty filter element is then weighed. This weight is compared to the clean element weight to determine the total Dust
Capacity. The amount of dust retained by the filter is divided by the total amount of dust fed during the test to determine the Cumulative Efficiency.
The K&N filter achieved the following results:
- Dust Capacity: 305grams
- K&N Cumulative Efficiency: 99.05 %
Now, I'm just like anyone else, typically skeptical of manufacturer claims.
I find it amazing though that people will agree and believe MOST claims, especially numbers (think about wet/dry boiling points of brake fluid, HT/HS or Cst of oil, etc), yet - when it comes from K&N - it's immediately dismissed. Even when they (K&N) claim their results come from an independent lab.
I'm certain that K&N filters do allow more dust than a highly efficient (see: good) paper filter that is properly sealed. Question is, is that percentage more harmful within say, 500k miles?
Jim, that's a good test you did, however unscientific it might be! I think that is something I'll do as well. I figure that climate and condition would matter quite a great deal on the results.
I am more apt to believe it because I've personally seen them destroy an engine in less than an hour, lap by lap smoking more each time until there was no compression left.
Seeing is believing. The figures just confirm. Maybe ok on asphalt where there isn't much dirt, but even as I show at the beginning of this thread, the smog and smoke of the city will clog a normal filter.
Seeing is believing. The figures just confirm. Maybe ok on asphalt where there isn't much dirt, but even as I show at the beginning of this thread, the smog and smoke of the city will clog a normal filter.
I'm assuming this is some sort of racing you're talking about? If so, was there a tear down to determine the cause of the engine failure? That would be an interesting conclusion.
I guess I can't argue with you in regards to the city smog - I have no idea what conditions you might live in.
The locale that I drive in might be ideal. We have frequent rain, little dust, and hardly anything I'd call smog.
I'd have to assume, the only way to truly test how efficient a particular filter is would be to do an oil analysis.
I guess I can't argue with you in regards to the city smog - I have no idea what conditions you might live in.
The locale that I drive in might be ideal. We have frequent rain, little dust, and hardly anything I'd call smog.
I'd have to assume, the only way to truly test how efficient a particular filter is would be to do an oil analysis.
I ran oiled cotton gauze filters for years, some of them K&Ns, on and off-road, without any dire side effects but I came to conclusion one day that I preferred not basing my filter choice on "minimum standards" or "how much dirt my engine can take over 300K miles." I just feel the oil cotten gauze is to easily subject to errors and outside factors for it's efficiency, or lack thereof. In a perfect situation I think I can believe the advertised efficiency. But after the 2nd or third cleaning, maybe by a ham-fited guy like me?
When I hotrodded on the street, way back when, the extra flow of a K&N added a bit of power. Plus, in those days air filters were generally pretty restrictive (as much in the plumbing as the filters themselves), so there was some power to be gained with a switch. Nowadays, air filtration systems have radically improved and they are not the power robber of years past. I've run or seen a number of dyno tests of replacement "hi-flo" filter elements (all brands) in stock housings and you can't see any gains (usually) and if you do, it's right up there at the redline. A full intake system might do better, especially if it's an improvement over the stock plumbing. Even then, more airflow is most necessary once you've increased the VE and that's when a full intake system will gain power... or rather not lose any to insufficient flow.
All that said, my preference now is for clean air and fuel economy. And not spending money on air filters I don't need to spend. I'm all for cleanable filters when they are available and have the necessary efficiency. That's why I like the AEM so much. They list a very high efficiency and even advertise tests of a cleaned filter, even an IMPROPERLY cleaned filter.
When I hotrodded on the street, way back when, the extra flow of a K&N added a bit of power. Plus, in those days air filters were generally pretty restrictive (as much in the plumbing as the filters themselves), so there was some power to be gained with a switch. Nowadays, air filtration systems have radically improved and they are not the power robber of years past. I've run or seen a number of dyno tests of replacement "hi-flo" filter elements (all brands) in stock housings and you can't see any gains (usually) and if you do, it's right up there at the redline. A full intake system might do better, especially if it's an improvement over the stock plumbing. Even then, more airflow is most necessary once you've increased the VE and that's when a full intake system will gain power... or rather not lose any to insufficient flow.
All that said, my preference now is for clean air and fuel economy. And not spending money on air filters I don't need to spend. I'm all for cleanable filters when they are available and have the necessary efficiency. That's why I like the AEM so much. They list a very high efficiency and even advertise tests of a cleaned filter, even an IMPROPERLY cleaned filter.
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