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Thread: K&N Filters

  1. #1
    Eddie Foy's Avatar
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    K&N Filters

    Anyone using them on a C-180? Thoughts?
    "Put out my hand and touched the face of God!"

  2. #2
    FdxLou's Avatar
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    Yup. Love it.

    Lou1

  3. #3

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    Have two. Both have lived on the shelf for a lot of years. Switched to Donaldson. Do a search. Been talked about before.
    Last edited by stewartb; 05-08-2019 at 11:33 PM.
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  4. #4

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    Quote Originally Posted by stewartb View Post
    Have two. Both have lived on the shelf for a lot of years. Switched to Donaldson. Do a search. Been talked about before.
    http://www.supercub.org/forum/showth...l=1#post718277

    ”A lot of years”? Curious why you switched? Have heard good things about donaldsons flowing better than bracket, but never tried both on the same plane...

  5. #5

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    On my 180 the two primary foulers of an air filter are bugs and cottonwood. I found it impossible to clean the K&N filter media without damaging it. Soak it, carefully pick bug guts, etc, and re-oil? I could hold the filter up to light and see a thousand holes. No way that filter would protect my engine from silt and other abrasives my plane is exposed to. Donaldson filter media is much easier to clean and can be cleaned much more aggressively without showing pinholes afterwards.

    Fast forward to my Cub and I used a K&N because of availability. I found one that could be adapted to my custom airbox. On that plane the filter is similar to a round filter installation on a stock Supercub where the filter media is parallel to direction of flight as opposed to the 180's filter being perpendicular and taking direct impact. My Cub's filter end plate (like a Supercub's dome) takes the direct bug hits. In that application the K&N works okay.
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  6. #6

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    I cannot speak for airplanes but my experience with K&N has not been good. Look there is never something for nothing and that is what K&N promises across their line. I put one on my boat, a CG approved model. Performance was good but found my MAP sensor fouled in short order by the oil soaked dirt it let through. The plain old stock flame arrestor works way better.

    Equally so, I was thinking about putting one on my Turbo Diesel truck until I started getting reports from others about "dusted" turbos. Sure enough it was such a rash that K&N withdrew them from the market. I met a guy in the Army Reserve, a motor pool officer who told me in Iraq, there was only one filter brand to use and that was Donaldson on everything from the M1A1 to the Humvees. Using others, he said breakdown was assured from sand. As luck would have it, Ford contracted with Donaldson to build a "super filter" and I put it in. My compressor compared to others is bright and shiny. Did I loose some performance? Yep. Nothing is free.

    I'm sure K&N is better than nothing but mostly they are marketing hype. Better filtration and better performance do not go together. I even found you can "over filter" oil. I.E make it so restrictive you starve the engine for lubrication. Color me skeptical of K&N
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  7. #7
    hotrod180's Avatar
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    Quote Originally Posted by FdxLou View Post
    Yup. Love it. Lou1
    I've always run Bracket filters on my airplanes, including my current C180.
    Mainly cuz that's what they came with.
    Hard to imagine easier maintenance-- just replace with new at every annual for less than 10 bucks.
    What are the advantages to a K&N or Donaldson--
    an increase in MP?
    Cessna Skywagon-- accept no substitute!

  8. #8
    Cub Special Ed's Avatar
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    Didnt know they had them for cubs (how bout a c90 pa-11?). Have donaldson on my -11 but a k&n on my 7.3 powerstroke. Love it. Have never had oil pass through the intake tube which is what a lot of people claim. I reach up with a white paper towel into the tube every time i service it and it comes out clean everytime.
    I think where people get into trouble is not blowing them out and letting them dry thoroughly before oiling and reinstalling.
    I soap and wash it, then blow it out, then let it sit out in the sun most the day. Even after that i still blow more water out of the nooks and crannies. I dont do my air filter unless the pick-up is going to sit the whole day. Then a light coat of oil. I don't oil it untill the oil is running off either, just enough to turn the element pink!
    Thats just how i do it. Have been running them since they came out on dirt track cars. Reminds me i need to get one for this new/old '96 jeep ive got!
    Just my $.02.
    "There are 3 kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves." Will Rogers
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  9. #9
    BC12D-4-85's Avatar
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    I sometimes run the K&N on motorcycles. A quick wipe of the intake downstream with solvent on a cloth will tell if the filter was overoiled or is passing fine dirt. They need to be dry after washing to retain oil. And yes they can pass more fine dirt than some other types (see Donaldson's info brochure) but on floats or skis the one I had worked well. I think after some use the K&N filters better as debris accumulates.

    The reason I went to Donaldson on the last two planes (PA-11 & Taylorcraft) was the old Air Maze, Brackett, and K&N's wetted or oiled surface somehow attracts and captures bugs while sitting. They (midges) hatch periodically from the float pond water and will cover a Brackett or K&N in a few days. The Donaldson is dry and they leave it alone. I need all the flow my C-85 can handle.

    Gary

  10. #10
    cubdriver2's Avatar
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    No bug problem, I don't run a filter on my J4 on floats

    Glenna
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  11. #11
    BC12D-4-85's Avatar
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    We get winds in Interior Alaska through mountain passes (you've seen them Glenn) that carry fines or loess airborne that sometimes need to be filtered. Even passes 90+ miles away will deposit a layer on vehicles after a couple of windy days. It's a daily event in sunny summer when warmed air south of the mountains pushes north. In Anchorage and places near it's even worse at times. I have pulled filters when power is needed on bigger planes (hot-high DA) but usually leave them on if not. Easy to remove the whole element if twist fasteners are there or the foam element on a Brackett.

    Gary
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  12. #12

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    As mentioned; there’s no free horsepower.
    Ruined a diesel by running a K&N, turbo blades looked like they’d be sandblasted in half, fine dirt caked thruout the intake system as evidence of what made it past (properly maintained) filter.
    Im assuming filter material is similar thruout their line of product.
    Good for keeping small birds, pine cones etc out, but I certainly wouldn’t run one off airport.
    I run Donaldson on all my off-road equipment with never an issue.
    Donsldson has published some really good info on correct filter maintenance, do’s and dont’s, myths and facts.
    worth reading.
    Last edited by Oliver; 05-09-2019 at 08:48 PM.
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  13. #13

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  14. #14
    BC12D-4-85's Avatar
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    We can approximate the info from Oliver in #13 with a manifold pressure gauge.....temp install or permanent. Note the MP reading before engine startup then WFO during or just after takeoff. It'll be lower. Over time the spread may change as the filter builds contamination - dirt, water, bugs - or the engine wears or leaks form in the intake plumbing. Clean the filter and see if the WFO MP rises and the spread returns close to new specs. However....any buildup on the air filter can be compensated by increased flow around a carb heat flapper or through the alt air door on FI engines so this test isn't 100% guaranteed.

    A close calibration for the static MP gauge reading is to set the plane's altimeter to "0" feet and read the pressure window if there's still some numbers showing.

    Gary

  15. #15

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    Gary,
    interesting idea.
    not sure if it was mentioned in the speel that I attached but they (Donaldson) strongly recommend against attempting to “clean” filters.
    Instead, replace when needed or suspect.
    We use little pop up indicators, I guess like little MP devises,
    plumbed in downstream of filter that indicate when filter needs changing.
    I think your suggestion would serve the same purpose once you establish numbers.

    Doug

  16. #16

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    I didn't know about Donaldson filters before this and want to say this is why I like this site. I learned something and intend to try them.
    Thanks
    Jose

  17. #17
    BC12D-4-85's Avatar
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    There's a persistent rumor of someone using Uni-filter foam to replace the Brackett replaceable element (https://unifilter.com). Reportedly they flow and filter well enough in other applications. Plus they are allegedly easily maintained by cleaning and re-oiling. They sell sheets under their accessories section in various thicknesses, hole density, and even a dual density sheet. Must be for Experimental applications.

    Gary

  18. #18
    phdigger123's Avatar
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    There are some great challenges comments on this thread. I worked for
    DCI for many years in manufacturing and learned a lot about air filters. Most people clean their filters way too often. Use a restriction indicator to tell you when to service. The pop up indicators work great. A manifold pressure gauge is even better. A dirty looking filter does a better job. As the filter cake (dirt) builds up, the filter efficiency increases. Also every time you remove the filter there is a chance of getting dirt in the intake. Cleaning filters can damage them. Be careful. I would never use K&N for the same reason as others have already mentioned.

    Mike

  19. #19

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    K&N Filters

    Comparing airplane parts to pickup truck parts is a stretch. Take direct impact to the filter screen and cloth out of the equation and the K&N works fine.

    In a discussion about 180s specifically? For mine Donaldson, Brackett, and K&N are 1-2-3. My mechanic hates Brackett and would flip 2 and 3 but since Donalson supply is good its moot. For my Cub? K&N makes a ton of filter configurations so has the advantage for filters in custom applications. In that airbox I'd still prefer a Donaldson but there's no cross reference. Not a show stopper. I have no worries even when operating on silty soil. Very little silt makes it into the induction. Airborne silt? I try to avoid that at flight speeds regardless of the air filter. Paint and windscreens don't like abrasives at 100 mph.

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  20. #20

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    Click image for larger version. 

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  21. #21

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    My filter is in the front. Not a problem. If somebody stirs up dust by taking off ahead of me? I wait for the dust to settle. Anyone that operated off Hood Strip a few years ago after they top dressed with silt and before they did dust control control knows what I'm talking about.

    I’m not a big advocate of K&N. I use one because there’s no better solution for my Cub. In that application it doesn’t get hammered by bugs so is simple to clean so less prone to filter fabric damage. The 180 application is very different.
    Last edited by stewartb; 05-12-2019 at 12:50 PM.

  22. #22
    hotrod180's Avatar
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    Quote Originally Posted by BC12D-4-85 View Post
    There's a persistent rumor of someone using Uni-filter foam to replace the Brackett replaceable element (https://unifilter.com). Reportedly they flow and filter well enough in other applications. Plus they are allegedly easily maintained by cleaning and re-oiling. They sell sheets under their accessories section in various thicknesses, hole density, and even a dual density sheet. Must be for Experimental applications.
    Seems like that stuff'd have to be way better, as in better flow AND better filtering,
    to make it worthwhile using instead of just buying an 8 or 10 dollar replacement Brackett element.
    My opinion.
    Cessna Skywagon-- accept no substitute!

  23. #23
    BC12D-4-85's Avatar
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    It flows better depending on mesh size and thickness on a manifold pressure gauge (I've been told of course). 10 million motorcycle racers vying for Top Gun squeeze every HP out they can and engine longevity is critical. Uni filter pods are popular.

    Gary

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