Ok I guess it's time the below chart and data gets thrown out here...
There was an exhaustive ISO 5011 lab test conducted several years back which just further reinforced my belief that K&N's filters are POS's indeed.
" (quoted)
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." (end of quote from the lab test)
The below just one chart & comment copied verbatim from the multi-page lab test. The only thing the K&N topped the charts with was air flow... which is nothing, a screen door has great air flow through it.
View attachment 15745
In the chart above it’s important to note the different test durations for each filter. The AC Delco filter test ran for 60 minutes before exceeding the restriction limit while the AMSOIL and K&N tests each ran for 20 and 24 minutes respectively before reaching max restriction.
In 60 minutes the AC Filter accumulated 574 gms of dirt and passed only 0.4 gms. After only 24 minutes the K&N had accumulated 221 gms of dirt but passed 7.0 gms. Compared to the AC, the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt. (The lab's words, not mine)
If someone doesn't care how much dirt gets passed into their engine, the K&N would be a good choice.