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Topic Review (Newest First)
01-22-2011 05:48 PM
Kate I did some research on this some time back.
It took a good amount of searching but finally I got results looking for the specs on particulates that pass through air filters. I was comparing my WIX filter against a K&N. Went to their websites if i remember correctly and got the info from them.

The WIX beat the K&N.
01-22-2011 05:32 PM
Mr_RPM dang guys, thanks for the info, i guess no matter where you go its a debate, so ill just leave it at that. everyone is right and wrong at this point and we may never know. not untill the next best thing comes around and blows the doors off anything out today.
01-22-2011 11:10 AM
Loic on a jeep or other vehicule i would NOT use pod style filterof any brand. IMO those are for racing only.
i think the design of an air box is also to get dust particule to ..."slow down" before getting to the filter to maximize efficiency. the dust hit the plastic "elbow" kinda like your dryer at home , youll find lint stuck in the pipe at the elbow.
01-22-2011 10:38 AM
Jerry Bransford My personal negative feelings about using a K&N air filter did not start when I discovered that air filter test, that test just confirmed what I had experienced with the K&N that I used to run.

I was happily running a K&N up until 7-8 years ago until a friend noticed it and suggested we remove it to see what was inside the air intake tube and throttle body. He knew what to expect since we both wheeled in dirty grimy desert conditions. He suggested I wipe a finger inside the air intake tube and I was shocked how dirty and gritty it was, which indicated a whole bunch of dirt was getting past my K&N. He laughed and said he was as shocked as I was the first time he did the same thing.

Until I could replace the K&N with something else, I added an Outerwears prefilter to the outside of the K&N. A bit later, I noticed the air intake tube's interior was still not clean and I noticed the Outerwear wasn't fitting as tightly as it should, letting dirt in through the gaps. At that point I bought added an additional prefilter, a foam Unifilter. I couldn't simply go back to the OE air filter because I had a York compressor that took up much of the space the OE air filter box used to fit in.

You can see both of those prefilters pulled back below. It took TWO prefilters on top of my K&N to finally get the air intake tube to stay reasonably clean. That Jeep was stolen and my replacement '04 came with a K&N but no York air compressor so I was able to go back to the OE air filter box. I am now VERY happily running the OE air filter box and an AC-Delco air filter. Nope, no loss in any performance and my fuel economy is just as bad as it was with the previous K&N air filter.

For those of you who still want to believe their K&N air filters are effective at keeping the dirt and grit out of your engines if you wheel in dirty/dusty conditions, be my guest and continue running one.
01-22-2011 10:35 AM
Plowboy1970 I have an Amsoil air filter in my 98 GMC Sierra that I put in the first month of owning it in 98. It has 140K on it now. Motor has never been open and runs Mobil 1 synthetic too. My 98 Wrangler I just bought has a K&N replacement filter in it now. For my street queen Jeep it will probably stay there.
01-22-2011 07:13 AM
m.rehme For what it is worth I have run one on a 1999 Dodge Cummins since it was new. 406,000 miles and running strong, clean it once a year.
For two years I drove in West TX. a lot, would leave a lot of very fine sand in the sink. If the K&N was that bad of a filter it had plenty time to dust the motor.
01-22-2011 07:13 AM
Neil F. If you do drive in heavly dusty/dirty conditions, the K&N is not the best choice. If you are not in dirty conditions or very infrequent, the K&N is fine. I have a drop in K&N on the TJ from the PO. It's a daily driver with a few off road trimps a year and not in heavly dusty conditions.

I've used them for over 20 years. 170k on my 99 Durango and for 260k on my 89 Mustang (140k on one motor and 120k on the second motor - motor change not due to K&N)
01-22-2011 02:02 AM
rrich K&N Air Filter Test - Tech Articles - Mopar Muscle Magazine

Interesting how test results can vary depending on who is selling what -
Some tests say K&N is less restrictive than Amsoil, the other says Amsoil is.

Air Induction

K&N Air Filter Facts

The filters in the oft quoted ISO test are flat panel filters for a diesel. They are considerably different than the ones Jeep uses.
Here's what an internet search found:

AC a1618C
ACDelco A1618C Air Filter - Reviews & Prices @ Yahoo! Shopping

Baldwin pa4134
Baldwin Filter PA4134 Air Filter

uni uaa 103
Internet does not show it's existence

wix 46678
Wix WIX 46678 WIX Air Filter - Reviews & Prices @ Yahoo! Shopping

purolator a 455314
Foam filter - no picture

afe 73-10062
aFe 73-10062 at AutoAnything

K&N 33-2135
K&N 33-2135 at AutoAnything

Drop in filters still use the very restrictive airbox and the tiny inlet funnel.

Doing a search on the internet shows many different tests for different vehicles, Mustangs, Diesel Truck, Motorcycles etc. But the only ones for Jeep were done by off road magazines - of course they will make sure their advertisers win.

Is it because Jeep is a 4 letter word?

I'd still like to find a small centrifugal filter that can be made into a 2 stage filter by feeding it into another paper, oiled cloth, or foam filter. If the capacity proves to be too restricting, then a dual parallel system could be fabbed.

But - use the white rag test on yours!
01-22-2011 12:26 AM
s3nt3nc3d I have no proof one way or another on a properly working K&N filter, however, K&N themselves say oiling your filter properly and as often as they recommend is crucial to proper filtration I believe...or something like that. So while the filter may flow and filter just fine...using it exactly as the instructions tell you to can make a HUGE difference as well.
01-22-2011 12:05 AM
meyers I use K&N filters on both my Jeep(Stock Box, Panel Filter) and my 2010 Dodge. I have used them for years on all different vehicles, motorcycles, snowmobiles, etc. and will keep using them do they work and better or worse I have no scientific proof. . I do know I have never had a major engine failure in any vehicle I have had them on, as for the dirt in the intake you will get that with any filter paper or K&N. My 2010 Dodge when I took the factory air filter out, there was dirt. I cleaned it out and put the K&N in I didn't see any last time I checked it. To each his own, trick is to keep them maintained and after oiling them let em sit and drip off in a warm place for a bit.
01-21-2011 10:58 PM
rrich Here's the real test that was done - all of it:
ISO 5011 Duramax Air Filter Test Report

Here's K&N's rebuttal.
K&N Air Filter Efficiency Testing

If you look up the part numbers for the others - big ones made for diesels you'll see it's comparing apples to oranges.

Is that valid?

Bottom line is use one of the others - if you can find room for it. Since they have so much more surface area they should be less restrictive.

It's your engine, believe what you want.

Try the clean rag test yourself - see how much crap gets in. Try driving it - you'll feel the difference between them.
01-21-2011 09:15 PM
Mortalis5509 Looks like the ISO test says it all there folks.
01-21-2011 07:54 PM
Jerry Bransford Here's a good chart with the text to go with it... and anyone who doesn't think a test performed to ISO standards isn't a valid test needs to better understand testing procedures and how exacting a test must be done if it conforms to the ISO 5001 standards as that air filter test did.

The below excerpts were all copied from the test results. There are many other charts and data within the test but the chart below and the comment just above it pretty well sum of what was a very lengthy test of a whole bunch of filters in a laboratory setting.

"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."

"In the chart below 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 574gms of dirt and passed only 0.4gms. After only 24 minutes the K&N had accumulated 221gms of dirt but passed 7.0gms. Compared to the AC, the K&N “plugged up” nearly 3 times faster, passed 18 times more dirt and captured 37% less dirt. " (lab results text, not mine)
01-21-2011 07:42 PM
UnlimitedLJ04
Quote:
Originally Posted by Unlimited04
The K&N Problem:
ISO Course Dust Test of multiple brands of air filters - K&N clog faster and passes 3-4x more dust than paper filter: ISO 5011 Air Filter Test Report.

Fine dust passing through a K&N in the stock TJ airbox: How good are K&N filters?

Why does this matter? Dust = silica. Read about silica here: Recognizing the Signs and Symptoms of Silica Contamination from Practicing Oil Analysis Magazine, January 2006.

The UOA (used oil analysis) with observed silica content in street driven vehicles: Threw away K&N's due to high silicon in UOA's - Bob Is The Oil Guy
From: FAQ - Cold Air Intake - JeepForum.com
01-21-2011 05:35 PM
rrich The pre-filter stops the big chunks of dirt and mud, butterflies, stuff falling off Hummers, etc.. And it helps keep the water off. It's just a fine mesh material similar to a ladies pantyhose.

Whether paper, cloth, or foam it's a good idea to use one.

We used to use pantyhose over our foam filters on the race cars - dirt track Sprint Cars. And a scarf over our mouths for the same reasons.
01-21-2011 04:42 PM
L.A.Offroad A few years ago I had this same talk with a friend of mine.I was at a parts store and picked up a K&N box and right on the box it said "for ultimate filtration use K&N prefilter number ____" That was on their own box.That ought to tell you something!!!!
01-21-2011 04:35 PM
rrich If you trace the source on that "study" you'll find the filters were not tested by the Feds or by any reputable lab - ISO is just the standards used for testing. On that test that's quoted all over two guys were testing for application in Diesels, not gasoline. The dirt they used is not the same auto mfgrs use for testing. The other filters were not the same filters we'd use on Jeeps - they were bigger and higher flow - except for the K&N. Do a search on the web to find the original story and how they did it.

Any filter, especially paper, gets leaks. The light bulb test is valid. You should do that with any and all filters.

A paper filter when wet becomes a slimy chuck of goo - look at the toilet paper in your potty! The cloth filter doesn't fall apart like paper, and the oil on it helps repel the water.

Look at this forum - lots of people complain the K&N gets dirty - that's what it's for! If it did not get dirty like so many others it would mean the dirt is going into your engine.

Dirt catching on the oiled surface becomes oily too - then it becomes part of the filtration. That's why it shouldn't be cleaned so often. Even if it looks bad, it's still working. When paper looks like that it's plugged.

As far as restriction goes - the paper type is not much more restrictive than the oiled cloth - when it's clean. But - the stock airbox filter system is. The long tube, the air having to reverse directions, and the tiny inlet to the box is. The box is not only a filter, but a silencer to meet Federal and state noise regulations. Just like the 100lb stock muffler - it restricts - but it has to drop the noise level to meet the standards - else they cannot sell the cars!

Now - so a little calculating -
Cruising you usually run at around 2000 RPM.
Calculate the airflow needed at that speed - or any speed.

Here's the formula:
4.0 Liters times 2000 RPM divided by 2 (it only injests air every other cycle) == 4000 liters of air needed EVERY MINUTE. Picture 4000 Liters of soda! That's a bunch!
Picture all that crowding through the tiny airhorn on the box.

In order to get enough air the engine needs you have to open the throttle farther. About the only time you notice a difference is pulling a hill - you cannot open the throttle enough to get what the engine needs. The argument it only restricts at High RPM and Wide Open Throttle is hype. It needs air no matter what the speed.

The folks that found dirt passed into their engine - they'd find the same thing on any filtering system if it isn't sealed right. The stock box the plastic warps, the paper element doesn't fit right, it bypasses too.

The screw type clamps tend to "bunch" the rubber connectors, making a gap. Always seal those connections with several wraps of tape. Stock or aftermarket.


I ran K&N for a long time. I always tested the system by running a clean white rag down the intake tube and a visual inspection of the throttle body. It was always nice and clean (same test on other people's stock boxes with paper elements usually weren't as good.)

One day it came out dirty. I could not find a leak where the dirt got in - light test. There had to be a hole I couldn't find. I switched over to a True Flow Oiled Foam filter (problem is, they are no longer in business.) It "feels" more restrictive than the K&N, but not near as bad as the stock junk.

I'd like to find a centrifugal filter as a prefilter, then a good secondary to catch what it didn't.

But - the debate will go on no matter what anyone says.

Do the rag test no matter what you use.
01-21-2011 04:21 PM
Loic well.... ill be talking about k&n OEM replacement filter. i live in vegas, lots of dust here. i have kn oem replacement, on my bikes and jeep. i didnt buy them for better performance, but they do a good job keeping the dust out. the reason i have them is once dirty, i clean them, dry them, oil them and put them right back in. it does work for me.
01-21-2011 04:17 PM
Atthehop If he is that smart then why isn't he an automotive engineer.
01-21-2011 04:14 PM
Mr_RPM we made a bet, i told him to grease his intake after the filter and run 1 of each filter for the same duration of time (1 full tank of gas) and we will see the condition of the grease after each run and see whats the cleanest.
01-21-2011 03:49 PM
Thesnufalufagus Tell him to take the k&n filter off his own car and get a white t shirt and wipe the inside of the pipe problem solved.
01-21-2011 03:38 PM
Mr_RPM Thanks, i have been googleing around but that chart illustrated quite well.
The more the merrier =)
Plus, this thread will help out anyone searching and possibly getting ready to post another Cold air intake thread. lol
01-21-2011 03:26 PM
Lawngnome The PO installed the K&N intake system on my jeep and I hate it. I would love to buy a stock intake to replace this with Or trade if anyone wants. I'm afraid of going through water with it also. Any way, here's the proof that it sucks. My poor engine
01-21-2011 03:23 PM
TOKKIE Did a google search and came up with a post off another forum from our very own Jerry Bransford. Check post #21.
Is the K&N FIPK worth it? - Page 2 - JeepForum.com
01-21-2011 02:52 PM
bobjenkins
Quote:
Originally Posted by Mr_RPM
So last night I got into this argument with a friend about K&Ns. He basically thinks they are the best all around.

beside the fact that my 4.0 I6 wont improve in performance/MPGs because the flow is not needed, but i also tried telling him that they don't filter very good compared to paper or even foam.

He works at car quest and thinks hes a mechanic (very smart, but not a mechanic lol) and claims he talks to all these filter reps and they all say K&N flows and filters better then anyone else. (who are paid to say so...lol)
Hes fallen to all these advertisements and K&N sponsored testing.

he then makes fun of me because I get all my proof from forums and thinks Im just full of false info from a bunch of rednecks and wannabes.

so, can you guys help me out and maybe shoot me some links to some facts, testing, testimonials, ANYTHING revealing the truth. Im just trying to prove that they don't filter nearly as well as paper. Im not worried about bringing flow into the equation as every engine is different.
I even try telling him to hold each filter in front of a light and you can blatantly see openings for the dirt to go threw, he then tries saying after oiling it you wont have that.
thanks guys =)

even if I cant get it threw his head, i atleast want him to second guess in his mind.
Generally you ain't gunna see much improvement on any engine , the advertising on some of that stuff is ridiculous

I say buy him a knn filter then install it for him and tell him to drive and see if he notices difference . Then reveal that you didn't actually install it
01-21-2011 02:44 PM
Mr_RPM
I need some proof/tests showing K&Ns poor filtration

So last night I got into this argument with a friend about K&Ns. He basically thinks they are the best all around.

beside the fact that my 4.0 I6 wont improve in performance/MPGs because the flow is not needed, but i also tried telling him that they don't filter very good compared to paper or even foam.

He works at car quest and thinks hes a mechanic (very smart, but not a mechanic lol) and claims he talks to all these filter reps and they all say K&N flows and filters better then anyone else. (who are paid to say so...lol)
Hes fallen to all these advertisements and K&N sponsored testing.

he then makes fun of me because I get all my proof from forums and thinks Im just full of false info from a bunch of rednecks and wannabes.

so, can you guys help me out and maybe shoot me some links to some facts, testing, testimonials, ANYTHING revealing the truth. Im just trying to prove that they don't filter nearly as well as paper. Im not worried about bringing flow into the equation as every engine is different.
I even try telling him to hold each filter in front of a light and you can blatantly see openings for the dirt to go threw, he then tries saying after oiling it you wont have that.
thanks guys =)

even if I cant get it threw his head, i atleast want him to second guess in his mind.

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