Paper or K&N filter ?

I'm very wary of charts, as they can (and usually are) be adjusted to the testers whim. I didn't read anywhere on what the circumstances were for the test. They could've very easily adjusted the air flow rate so that the amount of air resistance from the filters was the same on all levels, resulting in the higher-flow filters having much more air flow than the stock filters, and therefore sucking in more air and debris. That's what makes me look at these charts with a grain of salt, they don't mention how their tests were done with airflow pressures anywhere. I mean look at the efficiency chart; the difference is 3.13% between AC Delco and K&N, yet their charts make the K&N look just horrible compared to the AC Delco.

I guess you didn't see the link I provided. It is www.nicoclub.com/archives/kn-vs-oem-filter.html

Notice near the beginning they go into a fair amount of detail on how the test was performed including:

"SCOPE:
This report presents the results of an ISO 5011 test of several air filters designed for the GM Duramax Diesel. The test was independently performed under controlled conditions using a $285,000 machine at Testand Corp of Rhode Island (manufacturer of the machine).

Arlen Spicer, a GM Duramax Diesel owner/enthusiast organized the test. Testand offered to perform the tests at no charge. (These tests typically cost approx $1700.00 per filter). Ken (and employee of Testand), a Diesel enthusiast and owner of a Ford Power Stroke Diesel, shared Arlen’s interest in performing an accurate unbiased test of different types and brands of diesel engine air filters.

The filters used in the test were purchased retail and donated by Arlen and other individual Duramax Diesel owners. The detailed reports from the test have been compiled and are presented in the following pages. The final pages of this report present the behind the test.

ISO 5011 Test:
The ISO 5011 Standard (formerly SAE J726) defines a precise filter test using precision measurements under controlled conditions. Temperature & humidity of the test dust and air used in the test are strictly monitored and controlled. As Arlen learned in attempting his own tests, there are many variables that can adversely affect filter test results. A small temperature change or a small change in humidity can cause the mass of a paper filter to change by several grams.

To obtain an accurate measure of filter efficiency, it’s critical to know the EXACT amount of test dust being fed into the filter during the test. By following the ISO 5011 standard, a filter tested in Germany can be compared directly compared to another filter tested 5 years later in Rhode Island. The ISO 5011 filter test data for each filter is contained in two test reports; Capacity-Efficiency and Flow Restriction.

Capacity and Efficiency:
The Capacity and Efficiency test report presents the test results of feeding an initially clean filter with PTI Course Test Dust (dirt) at a constant rate and airflow. The course test dust has a specific distribution of particle sizes ranging from less than 2.5 microns to greater than 80 microns (see table below).

Every filter is initially tested at 350 CFM and the Initial Restriction or differential pressure across the filter is recorded in IN-H20 (Inches of Water). The filter is then tested by feeding test dust at a nominal rate of 9.8 grams per minute with a constant airflow of 350 CFM. The test is continued until the flow restriction exceeds the Initial Restriction + 10 IN-H20.

At this point the test is terminated and the amount of dust passed through the filter (Accumulative Gain) is measured. Dirt passing through the filter is captured in the Test Station’s Post Filter. The exact amount of dirt passed is determined by measuring the before and after weight of the Post Filter.
Similarly, the amount of dirt retained by the Filter under test – Accumulative Capacity – is measured by taking the difference between the before and after weights of the Filter. From these results the overall % Efficiency of the filter is calculated. This test also indicates how long a Filter will last before replacement is required (or cleaning for reusable filters).

Flow Restriction:
This report presents flow restriction of a clean filter resulting from an increasing airflow. The differential pressure restriction across the filter is reported in inches of water (IN H2O) versus Air Flow in cubic feet per minute CFM.

Data from these reports has been compiled and presented in the following bar graphs, plots and data tables."

Please understand that I have no axe to grind. It doesn't bother me one way or another what filters anyone uses. I only presented the information so folks could make informed decisions. Also, I am not a K&N hater. I have been using their oil filters on my bike for many years. Ed

Got my bike in Nov 19th, 1980..... 1,700 miles.......... Got the header in the winter of 81 and went "open" air box till 83 and stock carbs.

I then went with open 29mm smooth bores from 83 to 2004 and open stock 24mm carbs from 04 to 06........... a few months after joining here (in fall of 06) it got parked till I went with the 700cc kit in 2012. Had 29.000 miles then.

Comp when bought was 155-150-145-155 checked it often every couple years and stayed right there for many years...... after 29,000 miles it only fell to 150-145-135-150 (and I did not baby it) ( Ran it power shifting to 2 to 300 in the red a dozen or more times a year every year) .....so me running no filters for 25 years and 27,000 miles was not all that hard on it. :laugh: On my first post here I stated it was 150-145-145-150 at 29,000 miles but have since found my records and changed that.

When I tore it down I found out the low number from#3 was from a scored piston and cyl (1 inch wide) next to the right side pin and was there from the start. Other pistons and cyl looked very good. He PO always started it full choke at 4,000 rpms and left it there till warm so I'm sure it happened then due to no oil flow for the first second or two.......... I use APE pods now but may consider velocity stacks when I go back to the smooth bores next year.

Bought a K and N for my Kia daily driver when I first got it hoping to pick up a few miles per gal but it stayed right at 31....34 on longer trips. Kinda has a 4 barrel sound to it when kicking it down in passing gear....some old guys never grow up but move way slower.

Ah, YES...there's that critical information needed. So they did do it properly- AWESOME!! The data just seems very much geared against the K&N and other hi-flow filters. Hi flow filters are going to do that though, it's just not possible to have the same amount of square area having more flow without some adverse results of filtering, that's just physics. But heck, I'd take a K&N filter over nothing at all, which some racers do. I'm really surprised that Fram isn't in there (really? they couldn't get their hands on one of these?), the only filters I've heard of is WIX, Amsoil, K&N, and of course AC Delco.

K&N Filters for me and all of my vehicles. It is your choice and I choose to continue to use these filters for as long as I ride.

Paper filters will swell and restrict over time with the moisture that is in the air. Never have I had any grit or dirt on found on the intakes side of my carbs. If it is too small to see on your finger, then it won't do any harm going through the engine for me. I commute on my pod-filtered GPz550, daily about 300 miles a week. Clean and oil the filters about once a year.

I remember reading when I first started riding a article. The writer said a motorcycle engine can suck up a whole chopped up chicken and still run to some degree. :ohmy:
I stopped running paper filters in the early 70's when in Santa Monica I had to ride to work in the rain. A flooded intersection and a big truck shut the bike down. I had to take the filters off for it to run. From then on, they just wouldn't work right. It was a 350 Honda with the filters on the sides. Never again. :whistle:
Steve

Kz550's often suck in a choke flap and somehow spit it out. That's a thumbnail size piece of zinc plated steel. Rarely do they actually get stuck in a valve, so its pretty amazing. But still, that's not a reason to use 1/4" mesh wire as a filter.