Hello Teener World,
I have been a suspended oil foam filter fan since my motocross days (50 years ago) but just bought a brand new Mann paper air filter. My K&N is looking quite worn out and my flaps guy said why bother doing the cleaning and oil anymore? Just buy a quality new paper filter and be on your way. So I did and would love to hear what others have to say about the topic....thank you very much to all!!
gg

I think I mean gauze instead of foam....yeah that's it....gauze with oil on it....K&N brand....vs. paper....Thanks,
gg

The K/N has bigger holes in it to let more air in.
And many tests and people think too many particulates also

The stock filter likely filters better

I've never seen a factory installed cotton gauze filter on anything...
Ferrari, Lamborghini, Bentley all have paper filters. They are usually very large.

The K&N style filter was originally designed for off road racing where the environment could be extremely dusty, and a paper filter would become clogged much earlier.

So, unless you're in a dust bowl a paper filter is a FINER filter than a gauze.

It does a better job of filtration up to the point it clogs...

Another possible issue with the K&N style is a EFI system with a MAF sensor.

These are either in the filter housing or the intake tube to the throttle body and the oils that are in the K&N filters tend to coat the fine wire sensor and screw it up.

Check engine lights, strange running are the end result.

All you have to do is clean the MAF.
It's not hard.

But, by the third time you're ripping it out and carefully cleaning an almost invisible wire you end up putting a paper filter back in...

I used an ancient KN on my old opel gt in the last century, I put one on my mustang and one my 914. I find it let's the engine breath better across the board but of course the value increases at rpm. Cleaning them is easy, maybe every three or 4 years under normal circumstances. I never buy new filters. Is the filtration better or worse? No clue, don't really care. Never had an engine fail because of my air filter. I have had crappy paper filters that choked off an engine though. Paper filters vari in quality greatly and to get the flow of a kn you need a much bigger filter.

That said, the box design in the opel and the 914 makes me cringe. On the opel I went with the normal stack and didn't have to use the box (wouldn't fit on a Weber anyway). On the 914 you don't have a ton of choices on the d-jet. Air has momentum and a 90 degree turn like that helps nothing.

Engine masters did a cool comparison this year if you have motortrend. However they couldn't measure how well they cleaned the air, just the effect in power from various papers and a couple of cotton oil filters.

paper

Wix paper element.

Did testing 20 years ago for a company I work for and we ran test engines to do the test. K&n filters were equal in filtration to no filter at all. Major engine wear. Better flow but with a major drawback. Paper is way better at filtering. Much less engine wear

So does anyone make paper filters for IDF style carbs? I think all I've ever seen are the ones that need to be oiled. Anyone provide a link?

Please share data if you have it.

Paper filters for Webers at CIP1.

Commonly known data in the industry

Here is a academic study:

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https://doi.org/10.1016/j.protcy.2016.05.063

You all have me curious now about my foam ITG filters on my carburetor car.

Same or more likely worse. Foam typically worse. It depends a lot on foam density and whether you are using single or dual layer foam filter (coarse outer - fine inner) and whether the foam is oiled at all.

Very poor filtration compared to paper.

Note: I’ve used K&N for years on dual Weber setup. You just have to accept that filtration is in exchange for better flow. I tried paper filter on Webers once (without rain hat) and got caught in rain. Filter promptly got water logged and that was the end of that. Would be interesting to know how they do with a good rain hat.

As a side note: the filtration efficiency of K&N or foam increases as the filter gets dirtier but of course flow goes down accordingly.

Another good link to a more definitive ISO test than the basic academic study.
https://www.nicoclub.com/archives/kn-vs-oem-filter.html/amp

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I do not as it was proprietary testing that I performed. NDAs and such

I’m still reeling from the death of Brent Brock. His contributions to this forum should not be underestimated with how well he documented so many details of his restoration.

Wanted to take a moment to remind others of the amazing work he did recreating the European style air filter that worked with a standard paper element. This was all hand built (except the center air box - VW part)
The details are in his thread.

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http://www.914world.com/bbs2/index.php?sho...290&st=1720

There are commercial versions of this available (CSP I think?) but they are crazy pricey $900 or more. But if you have a high dollar engine - it is the way to get OEM type filtration and protection for that engine.

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This was my drag bike. Klemm research did the head reshape and the porting and I did the rest. I had to make custom intake manifolds to fit two 38mm Keihin's. after shoving those in there, I had room for a couple K&N's. End of that season I disassembled and found two wiesco's totally ruined. I diesel bathed everything, honed the cylinders to seat the new rings, reassembeled with new pistons, the K&N's and Outerwears End of that season it was time for more rings, But that was it. I loved the performance of the K&N's, but don't forget your outerwears.

Paper filter option for the triple barrel weber IDA 3C's?

I use these with my rain hats on my 911 engines. Round filter that fits great when made into a oval.

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john

I know I have an extra set of paper ones I won’t be using.

Have you had them out in a hard rain? Curious how well the rain hats work with paper elements.

Would really rather have paper element for filtration.

My only experience with paper elements on an /4 with Webers and no rain hats didn’t end well. I really like the look of the K&N type setup vs the bulky blob stock air cleaner for the six.

@targa72e

I take responsibility for finding that paper one. The height is about 1/4" more than the
k&n so so may need longer bolts for the covers.

Our '72 originally came with an oil bath air cleaner before the PO carbureted it. I've been gathering all the parts to put FI back on it during its restoration, including an oil bath air cleaner.

Not 100% settled on whether to keep it stock or "upgrade it" to a paper element air cleaner. Leaning towards keeping everything stock. Or at least "stock appearing". For example, the motor went from 1.7 liter to a 1911, but will still look like the 1.7 externally.

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Have you had them out in a hard rain? Curious how well the rain hats work with paper elements.


No, but the reason I switched is I did have my previous set up get rained on hard while parked. This was early style 911 system used on Carbs and MFI. With older rubber it did not seal well and the engine was actually hydolocked and the float bowls were filled with water after a thunder storm (this was on the way to RRC 2022). Normally the car is not used if it is going to storm.
Decided I should change filter system and water shields looked less likely to let water into carbs and engine. This filter has a wire mesh support so not too worried about moisture that might get sucked in and get filter wet.

john

Bath type filter really well