PeachParts Mercedes-Benz Forum - View Single Post - Tinkering around in a 28 yr old engine bay = broken items

dannym · #12 04-19-2007, 09:06 AM

Quote:

Originally Posted by bgkast

...... but I still have not seen any data to back up the claim........

I've seen data for and against K&N filters. I use it on my motorcycle but not on my Benz. I don't think there's enough of a performance gain to justify using it. Except for the cleaning and reuse part.
I just came across this in a quick search:

EDIT: Looking at the highlighted part at the bottom I'm now wondering what kind of effect engine oil has on these filters? I know my filter gets a lot of oil on it. Just wondering..

Quote:

Taken from the VetteNetters Forum:

Back in Dec & Nov there was quite a bit of discussion of the K&N Filter. At the center of the controversy were questions about the K&N's filtering ability (i.e. though its performance enhancing features aren't in doubt, people wondered how good a filter it is?) The discussion even got a bit heated with someone on the anti-K&N side coming out and saying the K&N pretty much sucks as a filter and isn't good for your engine.

The only post I saw, pro or con, that backed up its statements with test data was one citing a 1992 British Motor Industry Research Association dust filtration efficiency test of the K&N air filter. While this test has been discussed previously, there are some things in it that need review.

The test procedure was done according to ISO standard 5011, an international standard for air filters of the type used on heavy-duty and commercial vehicles, using a K&N oil-impregnated, gauze media commercial type filter measuring 16.14" long, 10.43" diameter, with an air flow of 550 cfm. The test "dust" used was "coarse grade" as specified by ACDelco standards for testing their filters. Coarse grade dust is made up of the following percentages of varying diameters of dust particles.

0-5 microns - 12%
5-10 microns - 12%
10-20 microns - 14%
20-40 microns - 23%
40-80 microns - 30%
80-200 microns - 9%

The starting pressure differential across the filter was 26.45" of water and the test ran until it reached saturation (31.49" of water) and then the amount of dust trapped by the filter (5.1307 lbs.) was compared to the total amount of dust introduced during the test (5.1680 lbs.) It took 102 mins for the filter to reach saturation and the filtration efficiency was 99.28%.

So, how do I qualify this test to put it in the proper perspective for the street high performance engine in a Vette?

* First, K&N commmercial filters typically use four-layers while units sold for use in passenger cars typically only use three. K&N has indicated the efficiency of their three-layer filters is 97% and independent testing backs up that claim.
* Next, the K&N commercial filter tested had more filter area that the typical air filter we'd see in a high-performance V8 application, such as a 3"x14" unit. However, since the efficiency of the filter media is about the same, the only "real" difference would be the time needed for it to reach saturation. It'd be less because, for a given amount of dust at a given flow rate, the smaller filter would plug up faster.
* Lastly, virtually no Vette run in street high-performance duty is going to see any coarse grade dust in any significant amount; unless it's regularly used on a farm or construction site.

Another test of K&N filters was conducted by the British MIRA in 1983 but this time according to the SAE J726 standard which is a bit more familiar in the US. This test was done using "AC fine grade" dust which is more typical of what a street engine would encounter under normal driving conditions.

0-5 microns - 39%
5-10 microns - 18%
10-20 microns - 16%
20-40 microns - 18%
40-80 microns - 9%

This test used a K&N three-layer motorcycle type filter with an airflow of 40 cfm. The initial pressure differential was .825" of water and saturation was reached at 6.85" of water. They introduced 15.6 grams of dust and the filter trapped 15.1 grams for an efficiency of 96.8% - very close to the 97% K&N claims for its street high-performance automotive filters.

Now, while a motorcycle filter is obviously "much" smaller than what a V8 would use, the efficiency should still be about the same and the bigger V8 filter should take longer to reach saturation.

In yet a 3rd MIRA test, using filters typical for V6 engines in high-performance sports coupes, two K&N oval filters (2.56"x7.48"x6.18" & 3.22"x7.05"x4.5") were tested. This test was run according to ISO 5011 using AC fine grade dust and the filter efficiency levels were 97.5% and 97.6% respectively.

All these tests showed efficiency levels well above the 95% most OEs claim and, in my opinion, convincingly show K&N, oil-impregnated, gauze air filters are not only capable of high filtration levels but also low airflow restricion. Many off-road racers must agree with me because a lot of them use K&N filters and, if they work in that kind of enviornment, they must be one heck of a good filter.

Also, Chrysler markets factory-approved performance kits for some of its US truck engines that includes a K&N filter and are covered under their factory warranty. You can bet they wouldn't warranty such a kit if the K&N filter didn't meet or exceed their OE filter efficiency standards!

In Japan, Nissan also markets similar factory-approved performance kits for a couple of their Japanese domestic models and, like the Chrysler kits, they include K&N filters.

Finally, one way a K&N filter can fail is if it's used - contrary to the manufacturer's instructions - without being oiled or with the "wrong" oil. If you use a K&N filter, you should clean it annually and reoil it every six months. If you operate your Vette in a dusty environment (the coarse dust) clean and reoil it more frequently. When you reoil, "only" use K&N's filter oil. Foam filter oil, engine oil, WD40 or ATF are "not" the proper oils and "will" significatnly degrade the filter's efficiency.

Danny