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Old 01-21-2021, 12:59 PM   #1
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This ought to stir up some controversy

Well I've done it now.
As an engineer I usually never believe the internet and especially "Opinions" posted.
I did my usual research looking for someone that has equipment and time to test theories.
K&Ns suck, well no. You know, gauze filters kill engines.
But here are some real test results in the attachment.
Yes gauze filters do allow more dust to get through. But how many have you drive on dirt roads? I don't. My GPS is set to "NO DIRT ROADS".
Since 1985 I have driven every vehicle with a Gauze filter. Includes motorcycles driven on dirt, and 13 cars probably 3/4 million miles.
Oh ya, no dust down stream of the filter...
I average 1-3 more MPG on cars.
3-4 more mpg on motorcycles.
Always more throttle response. (My Accord is jerky now)
More seat of the pants acceleration. That's uphill improvement.

But don't believe I don't know anything, JUST READ THE ATTACHMENT!
Attached Files
File Type: pdf OEM vs KN filters.pdf (196.4 KB, 10 views)
Full Timers.
2015 Fleetwood Discovery 40E on a Freightliner XCS chassis with a Cummins ISL9 pulling 1 and/or 2 motorcycles, '07 Honda Accord OR a 17' Runabout Boat.
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Old 01-21-2021, 01:07 PM   #2
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Where is the engeenering research on " Seat of the Pants Acceleration " ??

How is that measured ?
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Old 01-21-2021, 01:22 PM   #3
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Nothing new, race cars have been using open intakes for decades. It's merely a trade-off between power and engine durability.

K&N filters are affectionately known as engine dusters...
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Old 01-21-2021, 01:31 PM   #4
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So basically K&N's advertising is....false? Imagine.
Many years ago I used such filters on off road motorcycles. Simply because it was so convenient to hose the mud off after with no ill effects. Later I started racing and soon was able to put bikes on a water dyno at the shop. Took just about two experiments before all gauze K&N filters were thrown in the trash and never used again. I will never use one on anything I own.

Somewhere out there is some very well documented data from a fella who works at a company that has about the only setup in the world able to test filters meant for "clean rooms". Operating rooms, microchip production, stuff like that. He bought as many replacement auto air filters of a type that he could find. Tested new, partially clogged with a measured amount of debris, and fully clogged. Bottom line would be that many filters ranked well. Plain AC Delco paper types were consistently on top and K&N predictably at or next to the bottom.

I'd be very surprised that anyone can tell any difference in air filters in real world use. My personal road motorcycle of the last, wait, I don't know, since 1988 I have set up with adjustable jets on the carburetor. Meaning that I can and do reach down and tweak any and every carburetor adjustment I have while going down the road. Handy for altitude changes. I've run paper, K&N, no filter, and foam filters in it and never could tell the difference between them. Never did put that one on the dyno but it's had a few 1/4 mile timeslips over the years.
Small performance gains or losses tend to be a lot easier to recognize on small displacement high strung machines. If I did something to gain or lose ten horsepower on my coach I'm pretty sure I'd never know it. Still not putting a K&N on it though. When I bought it the filter was so clogged it was collapsing into the housing. We can tell the difference when a filter as dirty as THAT is replaced.
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Old 01-21-2021, 02:10 PM   #5
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I dont drive on dirt roads either. I was on a state highway last year while a field was being plowed on a windy day. I had to pull over until the visibility improved.

I drive Fords and I buy Motorcraft filters. Am I saving money? I dont know or care. I do know that if I have an engine failure while under the powertrain warranty that I have all receipts that show only Motorcraft fluids and filters were used.

One less thing to argue with ford about.
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Old 01-21-2021, 02:36 PM   #6
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While it is true that NEW paper filter out perform a K&N oiled gauze filter by a couple of percentage points this advantage does not last according to the research I have seen. If I recall correctly this research was reported in David Vizard's book about hot rodding small block Chevys. The point being that you need to look at the performance of the filter over the recommended change/cleaning interval. You also need to understand how gauze filters work. In a gauze filter the air goes around the oil soaked gauze and the dust, due to it's greater mass, hits the gauze and is stuck to the gauze by the oil. I have also heard that the oil in the filters causes issues with MAF sensors. In 3 cars and a motorcycle I have not experienced this issue. That said you need to follow the instructions and not saturate the filter, just mist it until it turns red. Will this change anyone's mind, probably not. It's the Ford Chevy, Dodge or blonde, brunette or redhead argument. Everyone has their preference and will probably never change their mind.
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Old 01-21-2021, 02:56 PM   #7
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Hot rodding, racing etc.........use them if you care to

RVs, Trucks, cars etc
I'll stick with the OEM Filter
WHY...cause that is what is recommended and don't have to wash/oil---wait until oil is absorbed to install another filter

I change oil/filter at 5K plus fuel filter
I change air filter if needed at 5k
Oil, fuel, air.....stay clean

I'm not in to saving a few pennies......time/effort are more important

Keep your K&N
Used them years ago and decided No Thanks!
Is it time for YOUR Medication or Mine?
Dodge 3500 w/Tractor Motor & NUWA 5vr
US NAVY---USS Decatur DDG-31
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Old 01-21-2021, 03:08 PM   #8
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I put the K&N filter in that came with my Banks system. All was fine untill 20,000 kms later and my MAF was dirty!

Now I'm back to the stock filter, and running fine.

No more K&N for me in anything with a MAF sensor. They may flow better, but not worth the chance of cooking my motor when it goes lean because the MAF is dirty.
Happy Glamping, Norman & Elna. 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!
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Old 01-21-2021, 03:35 PM   #9
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At least on the road racing side of things there are a couple of reasons to run K&Ns. First, not a lot of us run EFI with a MAF.

Second, it works well when clean and it's better than nothing. Unlike dragsters, hot rods and the like, a road race car is eventually going off the track, and this will usually create a huge cloud of dust, so you need something. You don't want to suck in a pebble and stick it in a valve.

I've seen a lot of classic dirt cars with no filters at all - but those engines had single digit MTBF anyway. Most newer ones run filters.

Third, engine life is not dominated by dust as a wear mechanism. On our cars at least, it's ring and bore wear due to piston rock. Other engines its bearing life. We're talking rebuild intervals in the six to 40 hour range. On a street engine that's just a couple weeks use, for a race motor its a season.

Fourth, packaging on a race car is really tight. K&N offer a number of filter designs for hard to fit locations.

None of which have any bearing on RV use.
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Old 01-21-2021, 03:45 PM   #10
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The vehicles you referenced averaged less than 58,000 miles. That's not many on modern gas engines, many won't even need plugs at that mileage.

I wasn't going to bother as you're just looking for controversy, but I broke down and skimmed your PDF. I saw no results of a single engine tear down or oil analysis. Why?

Without real data to back up your opinions that's all they are.
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Old 01-21-2021, 03:59 PM   #11
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Maybe we should never have stopped using the old oil bath air cleaners?
Good Travelin! Kirk
Full-time 11 years, now part-time.
Kirk & Pam's Great Adventure!
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Old 01-21-2021, 09:04 PM   #12
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Interesting how people seem to focus on "dust" being only off-road. Heck, I have dust in my living room. If you stand next to about any busy highway where it hasn't rained in a while, you'll likely see little squalls of airborne debris every time a car passes. Some of that is even little particles of rubber from tires. Wet your hand and press it to that highway surface. Inspect your hand. What is all that stuff stuck to it if the freeway is clean? Dust is everywhere a vehicle can go.
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Old 01-21-2021, 09:55 PM   #13
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Thank you, but I think I'll stick to the original recommended filters. Same with the oil filters etc.
Remember the old ads for toilet paper oil filters? I didn't try those either.
Jeff and Annette Smith
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Old 01-21-2021, 10:59 PM   #14
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I got caught in a dust/sand storm in NM a couple years ago and was damn glad that I was not running a K&N air filter. Imagine driving through this for a couple hours.
Click image for larger version

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