Author Topic: Reusable air filters  (Read 852 times)

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BlackIce619

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Reply #30 on: April 08, 2021, 04:28:34 pm
I'm a bit confused - I have the DNA filter (and removed the snorkel in favor of the open filter with the DNA cover plate or whatever you call it).
Is this the same as the K&N filter? I don't care about the sound, or the supposed performance upgrade, I just want to know I'm giving my engine the optimum intake protection. I do ride on duscty roads, and clean and re-oil the filter at intervals. Would I be better off to go back to paper filters and just change them on intervals? It's not about saving a few bucks, just preventing premature engine damage.
Sorry if this is taking the thread off topic.

As mentioned before. It is always a balance between allowing the engine to breathe a little more (Performance), or restricting it through a more thorough filtering process. I dont believe anything will ever exist where you can have perfect breathing engine and 100% particle filtration. In essence you would have to have a hospital-type HVAC system inside your motorcycle  :o.

If you truly do not care about performance and you want to filter out 3% more, then keep stock filter. If you want to let your engine breathe a bit more, increasing performance and MPG, then leave the DNA filter and enjoy life!
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Jack Straw

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Reply #31 on: April 08, 2021, 04:34:44 pm
Gosh, I wonder what the best oil for the filter could be?
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biscot

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Reply #32 on: April 08, 2021, 04:43:08 pm
Gee, sorry if I opened a can of worms. Maybe there's no true answer. I'll meditate on it and go back to worrying about oil filters.


BlackIce619

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Reply #33 on: April 08, 2021, 04:43:27 pm
Gosh, I wonder what the best oil for the filter could be?

Just use the same engine oil so that EVERYTHING stays lubed.



P.S. That is a joke everyone. Please do not that that comment serious. ::)
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Jack Straw

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Reply #34 on: April 08, 2021, 05:09:47 pm
Hey BlackIce,

It's a good idea there, to insert a "humor disclaimer".

Air filters, oil filters, oil for ANY application, and......SUSPENSION!!!!!!!!  get some of us really worked up.  Here's a totally unsolicited tip from a geezer;  don't EVER tell anyone what oil you use. It'll drive some guys nuts but it's good to rise above the fray.



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biscot

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Reply #35 on: April 08, 2021, 05:11:00 pm
 :D :D


NVDucati

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Reply #36 on: April 08, 2021, 05:12:21 pm
So, this is the problem as i see it: once the oiled-cotton filter gets dirty enough that all the oil dries out, it’s possible for dusty air to make its way through the more porous filter media and into your engine, whereas a paper filter with it's much smaller voids would simply become blocked.

Am I missing something?
You are certainly asking the correct and smart questions.
   It helps to consider a couple of differences. How are cotton and paper made? The cotton media is woven, the paper media is soaked and pressed flat. Then consider the difference between air and dirt. Air molecules are obviously much smaller and, in turn, much more "fluid"(fluidity). The air can weave its way through either material better than can dirt.
   Next consider the construction. When you grab a woven cotton filter, like K&N, you will notice the stainless steel screen on both the inside and outside of the cotton. That allows the material to be thicker and hold the pleats which are also deeper, providing more surface area (that also adds to the expense). Picture the dirty air having to race through a slalom course. The air molecules win. Then it is a mater of scale. The distinction is fluidity not porosity.
  Staying on the subject of construction for a moment longer, notice the difference between soft wider rubber gaskets compared to hard narrow plastic. Then picture micro-pounding(bouncing) from vibration those gaskets experience while trying to maintain the "coastline" seal against dirt particles.
   Back to one part of your specific question, "...whereas a paper filter with it's much smaller voids would simply become blocked." Actually that would be nice buy way, way before a paper filter gets literally blocked the suction of the intake will simply pull the dirt particles through the material. You might notice a bit of slower starting but it will still run.
   In the end both types have a finite duty cycle. The dirty air we ride through is the same for both.
 
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GravyDavy

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Reply #37 on: April 08, 2021, 09:17:15 pm
No worries GravyDavy. I was reacting to your question “Does anybody know if they are publishing the micron rating of a new, properly oiled one?” when I had just, minutes before, posted links to specific, independent information.

I truly get it that none of this might matter, at all, to some folks. But I guess I could have also mentioned that the FAA has certified K&N filtration for aircraft. One supplier cites:
“K&N re-cleanable air filter media
Up to 50% more air flow with the same dirt holding capability
NO ADS (Airworthiness Directive) 
Increased horsepower
Reported fuel savings of .3 to .5 gallons per hour”

A third to a half gallon saved per hour is a big deal for pilots. Not so much as a money saver but for the effect on available range. (from 6000ft you can’t just push your plane to the next gas station) Even if one only looks at it from an ecological viewpoint including the notion of the disposables… it is not just a drag strip thing. Don’t know if that matters.
   Last, how often one changes a air filter is subject to a lot of considerations. One consideration should be that as any air filter gets covered with dust, it creates a vacuum on the fuel intake side. Paper filters are more prone to eventually suck the particles right on through much sooner.

Thanks.  Being lazy, I rarely click on links.  It does sound like a K&N could be a worthwhile choice, and that if there ever were any problems, they've made changes to fix them.


Hoiho

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Reply #38 on: April 09, 2021, 12:32:30 am
You are certainly asking the correct and smart questions.
   It helps to consider a couple of differences. How are cotton and paper made? The cotton media is woven, the paper media is soaked and pressed flat. Then consider the difference between air and dirt. Air molecules are obviously much smaller and, in turn, much more "fluid"(fluidity). The air can weave its way through either material better than can dirt.
   Next consider the construction. When you grab a woven cotton filter, like K&N, you will notice the stainless steel screen on both the inside and outside of the cotton. That allows the material to be thicker and hold the pleats which are also deeper, providing more surface area (that also adds to the expense). Picture the dirty air having to race through a slalom course. The air molecules win. Then it is a mater of scale. The distinction is fluidity not porosity.
  Staying on the subject of construction for a moment longer, notice the difference between soft wider rubber gaskets compared to hard narrow plastic. Then picture micro-pounding(bouncing) from vibration those gaskets experience while trying to maintain the "coastline" seal against dirt particles.
   Back to one part of your specific question, "...whereas a paper filter with it's much smaller voids would simply become blocked." Actually that would be nice buy way, way before a paper filter gets literally blocked the suction of the intake will simply pull the dirt particles through the material. You might notice a bit of slower starting but it will still run.
   In the end both types have a finite duty cycle. The dirty air we ride through is the same for both.

Thanks NV, always appreciate your input.


GravyDavy

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Reply #39 on: April 09, 2021, 12:58:11 am
Just my opinion, but it seems to me that for the great majority of riders the only significant differences between the stock setup and the snorkel delete + gauze filter are:

Noise level

Wallet weight

And whether to clean&re-oil or replace the filter element.

Unless the stock paper element is truly dismally restrictive, there will be no perceptible performance difference, except maybe at WFO bouncing off the rev limiter. I would bet that the snorkel removal accounts for virtually all of the perceived performance change, and most of that is the "it's louder so it must be faster" assumption.

The stock paper filter has abundant surface area and net free area.  Lots of V8 hotrods with 4-barrel carbs have worked quite adequately with shorty filters using much less filtration material. A gauze filter may flow even better, but more than enough doesn't add any performance. If my assumptions and reasoning are correct, the choice to use a gauze filter mostly boils down to reusability. And that can be a good reason.

Let the flames begin.


Jack Straw

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Reply #40 on: April 09, 2021, 01:05:02 am
+1 on that.   This is sort of a classic forum mini tempest in a tea pot.  Is the darned filter reasonably clean??  If not, replace or clean it and go ride the bike.  Stop fretting over this small stuff.

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drums4money

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Reply #41 on: April 09, 2021, 01:52:53 am
Gosh, I wonder what the best oil for the filter could be?

Marvel's Mystery Oil guarantees 5 more hp. 
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gizzo

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Reply #42 on: April 09, 2021, 02:26:42 am
Just my opinion, but it seems to me that for the great majority of riders the only significant differences between the stock setup and the snorkel delete + gauze filter are:

Noise level

Wallet weight

And whether to clean&re-oil or replace the filter element.

Unless the stock paper element is truly dismally restrictive, there will be no perceptible performance difference, except maybe at WFO bouncing off the rev limiter. I would bet that the snorkel removal accounts for virtually all of the perceived performance change, and most of that is the "it's louder so it must be faster" assumption.

The stock paper filter has abundant surface area and net free area.  Lots of V8 hotrods with 4-barrel carbs have worked quite adequately with shorty filters using much less filtration material. A gauze filter may flow even better, but more than enough doesn't add any performance. If my assumptions and reasoning are correct, the choice to use a gauze filter mostly boils down to reusability. And that can be a good reason.

Let the flames begin.
+1.
That's what I was trying to get at, in less words.
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zimmemr

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Reply #43 on: April 09, 2021, 02:19:54 pm
+1 on that.   This is sort of a classic forum mini tempest in a tea pot.  Is the darned filter reasonably clean??  If not, replace or clean it and go ride the bike.  Stop fretting over this small stuff.

As usual Jack, you've summed it up nicely. 


viczena

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Reply #44 on: April 09, 2021, 02:26:16 pm
When paper and gauze filters are both new, no filter wins. But the gauze keeps the airstream open much longer. Paper detoriates quite fast.
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