K&N Filter Everything you ever wanted to know

[VWBeamer]

I heard tell, dat ya pa was a runnin' a e-soss pipe as big as a man's fore arm, n a 3/4 race cam wit corn liquor mixed in the tank, so ya can't rightly say it was da K&N

__. I dunno. Mah Gramppappy hed this '49 Fork Pickup - he ran a K&N filter for 30 years and it would git up to 90 mile an aarr. All he had to do wuz awl the filter and clean the birds nests n gravel outta the carbeeraider ever sprang. But it wuz prolly the changin the awl ever thoussan mile with 99-cent "SA" awl fum da Waw-mott that wuz even bedder than that K&N.

 

[Drivbiwire]

DBW: How many miles on the K&N filter in the picture? It looks very dirty, has it been cleaned and reoiled as per the instructions?

And also this thing about the surface area that always gets mentioned in these threads, that larger area = better filtration.
Is that true?
I would think that larger area = longer service life

I`ve always used OEM filters on all my cars but happen to have a K&N on my bike, I'm sure it filters the air good enough for a carburated 650cc single but wouldn't use it on anything with a MAF.

The filter had less than 10,000 miles, it was factory oiled BY K&N. It never made it to the first cleaning because of all the dust it was letting thru.

The car was driving in a NON-DUSTY environment that typically allows 80,000 miles or more on OEM filters when using the restriction meter.

 

[nicklockard]

Picking the nits off of the nits on the nits:

I make and operate equipment that is used to fill large power transformers with insulating oil. In doing so, we MUST ground everything in site (even when working in greenfield) - because of the static charge built up by insulating oil travelling through our neo/nitrile hoses can be sufficient to destroy the transformers insulating system.

A hundred thousand or so litres of liquid certainly qualifies as greater body size than Milliken's droplets.

Also another caution, Jack: you dismissed oil as not being "dry". It can indeed be at moisture levels in the single parts per million quite easily - which by any measure is VERY dry. (Wet tecnically refers to water content, not other liquids when referring to such phenomenae).

Yup, static charges accumulate for all sorts of reasons and not just from rubbing materials together. Example: solvents are stored in metal cabinets so they don't build up static charges. The metal is always dissipating charge to ground.

 

[Jack Frost]

static charge built up by insulating oil travelling through our neo/nitrile hoses can be sufficient to destroy the transformers insulating system.

....

Also another caution, Jack: you dismissed oil as not being "dry". It can indeed be at moisture levels in the single parts per million quite easily - which by any measure is VERY dry. (Wet technically refers to water content, not other liquids when referring to such phenomenae).

Static electricity, even if it is a small charge with very little energy can exist in voltages in the 10 or 100 of thousands, and even millions of volts depending how well insulated it is from ground. Computer chips (which must exist in your transformer insulating system) get fried if they see anything over 5 volts. In other words, it doesn't take much. Your system would be destroyed very easily if it got between a charge and a ground. The event would be undramatic. You wouldn't see any spark or smoke. It would just stop working as if you unplugged it.

I suppose different people use "wet" for different reasons. I was using the word generically to describe the process a liquid spreading itself around a dry object because of its surface tension (ie wicking). You are using the word "dry" as a way of describing the absence of water that exists dissolved in oil. As an owner of a tractor, I know that is not a good thing to have in the hydraulics.

Both uses of the word "dry" and "wet" are legitimate and can be fun to mix. It is a bit of a brain twister to think that a K&N air filter is no longer "dry" when it has been oiled even with "dry" oil. Better to call it "oiled" rather than "wet" with oil.

 

[nokivasara]

The filter had less than 10,000 miles, it was factory oiled BY K&N. It never made it to the first cleaning because of all the dust it was letting thru.

The car was driving in a NON-DUSTY environment that typically allows 80,000 miles or more on OEM filters when using the restriction meter.

Ok thanks, the K&N on my bike is cleaner than that after 10 000 miles and I drive 90% on dirt roads

Could you (or someone else) explain my question about surface area?

 

[ruking]

Ok thanks, the K&N on my bike is cleaner than that after 10 000 miles and I drive 90% on dirt roads

Could you (or someone else) explain my question about surface area?

For sure it would be interesting to see the difference on an a/b comparison. But, your bike probably flows (factorially) less air. TDI's have app 19 to 1 compression ratio. What is your bikes?

What about little to NO air flow restriction on stock oem TDI filters ( within the operations band) is hard to understand?

So if one is getting 80,000 to 100,000 miles per oem filter, with much better filtering action and inexpensively, why would one want an expensive cotton gauged filter that requires mineral oil which is expensive and coats the internals which were never designed to be "coated", and filters less effectively?

Let's see $7 to $12 per air filter ( lasting 80,000 to 100,000 miles) http://www.partsgeek.com/catalog/2003/volkswagen/jetta/air_intake/air_filter.html

vs $45 + $12 recharge kit= $57.00

/$12 per oem filter = 4.75 x to (BE) or 380,000 miles to 475,000 miles to BREAK EVEN.

 

[VWBeamer]

How does CR affect anything? LOL

 

[TDIJetta99]

LOL it doesn't.. I was laughing at that too.. displacement and rpm will be what determines the total airflow..

 

[ruking]

Nothing like missing the forest for the trees ... "your bike probably flows (factorially) less air" ? Glad you laughed however. Need to keep the use of "power enhancing" oil filtered media like K & N in a goofy factor perspective. So we hope one doesn't miss the forest for the trees, when it comes to power enhancing oil filter media like... K & N???

 

[TDIJetta99]

I think depending on the bike, it very well might flow about the same if not more than a TDI.. take for instance a Suzuki GSXR1000.. the newer ones are 999cc, slightly more than half the displacement of the ALH, and have a redline of 13700rpm.. More than double the rpm TDI's see.. I'd bet that bike flows more air at full chat than even a modified TDI..

 

[ruking]

Even at that, I still would not use a K& N filter on the Suzuki GSXR1000. Besides how many folks practially keep their motorcycles rpm @ 13,700 for: 6.25 hours 584 miles for 12.1 gals at a time vs say me doing that as a matter of course (not at 13,700 rpm) in a TDI?

But then on the other hand, I am sure Suzuki engineers have designed their air filtration systems knowing its specific demands. I bet they use dry oem media!!??

 

[RomSL]

I think depending on the bike, it very well might flow about the same if not more than a TDI.. take for instance a Suzuki GSXR1000.. the newer ones are 999cc, slightly more than half the displacement of the ALH, and have a redline of 13700rpm.. More than double the rpm TDI's see.. I'd bet that bike flows more air at full chat than even a modified TDI..

At full chat you have to double/triple the displacement of TDI. That's what we have turbo for.

Rough estimations show that modded TDI would flow at least twice as much as a bilke

 

[TDIJetta99]

even at less than half the rpm? I suppose it depends on the extent of the modified TDI..

ruking... I wouldn't use a K&N on that particular bike either.. How often is your TDI at full boost near redline? Mine isn't for any long period of time either.. Typically the 1000's highway cruise rpm is between 5000-7000rpm depending on the sproket sizing.. my brother's at the moment is about 6000rpm@80mph.. I imagine cruising the TDI flows a good amount more air due to the lack of a throttle plate

 

[nokivasara]

For sure it would be interesting to see the difference on an a/b comparison. But, your bike probably flows (factorially) less air. TDI's have app 19 to 1 compression ratio. What is your bikes?

What about little to NO air flow restriction on stock oem TDI filters ( within the operations band) is hard to understand?

So if one is getting 80,000 to 100,000 miles per oem filter, with much better filtering action and inexpensively, why would one want an expensive cotton gauged filter that requires mineral oil which is expensive and coats the internals which were never designed to be "coated", and filters less effectively?

Let's see $7 to $12 per air filter ( lasting 80,000 to 100,000 miles) http://www.partsgeek.com/catalog/2003/volkswagen/jetta/air_intake/air_filter.html

vs $45 + $12 recharge kit= $57.00

/$12 per oem filter = 4.75 x to (BE) or 380,000 miles to 475,000 miles to BREAK EVEN.

Ok, I doubt you even read my first post in this thread (posted about 24hrs ago) but if you did you misunderstood it.
I have not anywhere stated that the K&N is better than OEM, I wrote that I use paper filters in my cars and just happen to have a K&N on my bike. I even wrote that I wouldn't use an oiled filter on anything with a MAF.

I was just curious why the filter looked so dirty, asked DBW about the mileage and got a nice answer. Then you came in.

EDIT: oh yeah, the bike only has 650cc of displacement and a 7000-something redline, it doesn't flow very much compared to a TDI under boost. It has a very large filter if compared to the 1900cc TDI filter, that's also one thing that keeps it cleaner. But the filter in the OP still looks very dirty, no surprice the MAF was sad...

EDIT 2: still curious about the surface area thing

 

[ruking]

Ok, I doubt you even read my first post in this thread (posted about 24hrs ago) but if you did you misunderstood it.
I have not anywhere stated that the K&N is better than OEM, I wrote that I use paper filters in my cars and just happen to have a K&N on my bike. I even wrote that I wouldn't use an oiled filter on anything with a MAF.

I was just curious why the filter looked so dirty, asked DBW about the mileage and got a nice answer. Then you came in.

EDIT: oh yeah, the bike only has 650cc of displacement and a 7000-something redline, it doesn't flow very much compared to a TDI under boost. It has a very large filter if compared to the 1900cc TDI filter, that's also one thing that keeps it cleaner. But the filter in the OP still looks very dirty, no surprice the MAF was sad...

EDIT 2: still curious about the surface area thing

Yes I read your OP. Indeed two general questions was asked, applicable to the TDI's. Sorry you took offense two general questions, which you obviously subscribed to!!??.

So off topic, I don't own a bike, but if I did I would have stayed with oem specified air filters. I would of course deviate, if the sponsor/s aka like ...ah... oil media company's paid me to run its brand and paid for the engine replacements.

 

[nokivasara]

Ok, I agree about the sponsor thing!

Now I'm just waiting for an answer for the surface area question
Have a nice day!

 

[shadowmaker]

It has a very large filter if compared to the 1900cc TDI filter, that's also one thing that keeps it cleaner.

EDIT 2: still curious about the surface area thing

Are you sure about how large is that filter of yours?

Here's FFF vs OEM to compare about those surface areas.

The blue one is FFF, if someone missed it.

Here's a link that everyone interested in FFF should read. It's long but worth the time.
http://www.dieselplace.com/forum/showthread.php?t=55604

Sadly the original " ISO 5011 air filter report " is totally blocked from the internet and every thread concerning it locked... I wonder why?

 

[VWBeamer]

Holy crap, I thought my garage was bad....I feel better now.

 

[ruking]

even at less than half the rpm? I suppose it depends on the extent of the modified TDI..

ruking... I wouldn't use a K&N on that particular bike either.. How often is your TDI at full boost near redline? Mine isn't for any long period of time either.. Typically the 1000's highway cruise rpm is between 5000-7000rpm depending on the sproket sizing.. my brother's at the moment is about 6000rpm@80mph.. I imagine cruising the TDI flows a good amount more air due to the lack of a throttle plate

Actually a good question if not for proportionality. So for example on trips I like to cruise no more than 3,000 rpm/5100= 59% of redline. 3k is app 90/95 mph. So for example while I hear 5-7k on the example bike, I do not know what % that is of redline.

TDI's are not and never have been designed to be high revving machines. While I have not verified every VW's MY's owners manual, the 03/09 TDI's max torque figures are @: 1750 to 2250 / 1750 to 2500rpm: max torque @ 3,825/4000 rpm.

 

[Drivbiwire]

Now I'm just waiting for an answer for the surface area question
Have a nice day!

What are you talking about?

In regards to Area why is larger area with more available pores albeit smaller (1-7 microns) confusing you?

Add up the total area of the available pores, even though they are smaller there are more of them. More available pores the more air you can pass thru the filter media.

The more air you can pass which has been filtered to a smaller particle size the less restriction you have.

The less restriction you have the longer the filter can remain in service before each of those small doors slams shut due to dirt plugging them.

Eventually you run out of doors and the restriction rises hence the recomendation for installing a manometer to monitor actual filter restriction.

If you have another question about area please be more specific.

 

[shadowmaker]

Holy crap, I thought my garage was bad....I feel better now.

Luckily it's not mine either... Although mk2 is always nice.

 

[nokivasara]

What are you talking about?

In regards to Area why is larger area with more available pores albeit smaller (1-7 microns) confusing you?

Add up the total area of the available pores, even though they are smaller there are more of them. More available pores the more air you can pass thru the filter media.

The more air you can pass which has been filtered to a smaller particle size the less restriction you have.

The less restriction you have the longer the filter can remain in service before each of those small doors slams shut due to dirt plugging them.

Eventually you run out of doors and the restriction rises hence the recomendation for installing a manometer to monitor actual filter restriction.

If you have another question about area please be more specific.

No that was all I needed to know, if I'd known the huge difference in surface area it would have been clear to me from the start!

The surface area on the filters on my bike are almost the same, K&N vs OEM. Not quite the same but not that big of a difference as in Shadowmakers picture.

Thanks for your clear answers

 

[Jack Frost]

And also this thing about the surface area that always gets mentioned in these threads, that larger area = better filtration.
Is that true?
I would think that larger area = longer service life

Let me take a crack at answering your question. Does a larger filtering area make a better filter?

Yes and no.

The obvious purpose of an air filter ideally is to restrict particles that could damage anything behind it (MAF, turbo, engine, etc), but it must allow desirable particles (such as air) through. But no filter is ideal. They all restrict to some point due to air's viscosity, as well as the turbulence and friction air experiences moving through the filter media. So it follows that a filter that needlessly restricts particles that are needlessly small is bad as this restriction is at the expense of air flow. For instance, have you ever tried running with a gas mask on? Its hard. No soldier runs with a gas mask on unless his life depends on it.

An ideal filter has a consistent pore size and each pore is circular in shape. Since it is the media that causes restriction, ideal filters should have no media - all of the filter media should be pores. An ideal filter is one big pore like the intake inlet on a jet engine.

There is no such thing. Some pores come in all sizes and shapes and are defined by filter media which by its very existence will restrict air flow with turbulence and friction. The paper filters do not even have pores. The media consists of cellulose strands pressed together. The filtering ability of paper based media is an expression of the probability that a particle of a certain size will make its way through - much like a bullet making its way through a forest without embedding itself into a tree.

A good example of a close to idea filter is mosquito nettings, fish nets or chicken wire. Each pore is a hexagon or square shape that separates and keeps the big stuff (mosquites, fish, dogs, kids) from the stuff that we desire to allow through (air or water). Most of the surface are of the filter media is open pore and not the media itself that causes restriction. Another way of stating this one is an ideal filter is transparent. Well designed filters have a low density, that is, most of the area of the filter is open pore and very little of it is filter media.

So it is possible for a filter with a smaller filtering area to be a more effective than one with a larger area if the smaller filter had a consistent pore size and a low density and was still able to restrict damaging particles without restricting anything else.

Filters with a variable pore size are bad. Since air will flow through the path of least resistance, most of the dirty air will flow through the larger pores even if the small ones are not clogged. The smallest ones will usually clog up first allowing the larger ones to continue to pass damaging particles through. If a filter has a variable pore size, one cannot trust its condition with a manometer as well as it can with a filter with a consistent pore size.

To sum it up though. All things being equal, a filter with a larger filtering area will filter more air than a smaller one, but it is possible for a smaller filter to filter better and longer than a larger one of poor design.

 

[TDIJetta99]

Actually a good question if not for proportionality. So for example on trips I like to cruise no more than 3,000 rpm/5100= 59% of redline. 3k is app 90/95 mph. So for example while I hear 5-7k on the example bike, I do not know what % that is of redline.

TDI's are not and never have been designed to be high revving machines. While I have not verified every VW's MY's owners manual, the 03/09 TDI's max torque figures are @: 1750 to 2250 / 1750 to 2500rpm: max torque @ 3,825/4000 rpm.

The bike's redline is 13700, max hp@11k.. I can't find the torque numbers, but I assume with a 74.5mm bore and only a 57.3mm stroke that the torque peak is pretty high up, and not all that high of a number either..

 

[ruking]

The bike's redline is 13700, max hp@11k.. I can't find the torque numbers, but I assume with a 74.5mm bore and only a 57.3mm stroke that the torque peak is pretty high up, and not all that high of a number either..

So that is app 44% (of redline 6k/13.7k @80 mph) vs 51% (of redline TDI @ 80 mph @ app 2.6k /5.1=) I have read the cruising range on 4.6 gal tank is app 142 miles or 31 mpg (this is a swag, I do not know). @ 80 mph I can easily post 55 mpg. On longer trips @ 75 mph with bursts to 80/85 mph I posted 59 mpg and with multiple tank fulls. Normally I am just fine with 48 mpg, 584 miles in 6.25 hours.

 

[TDIJetta99]

So that is app 44% (of redline 6k/13.7k @80 mph) vs 51% (of redline TDI @ 80 mph @ app 2.6k /5.1=) I have read the cruising range on 4.6 gal tank is app 142 miles or 31 mpg (this is a swag, I do not know). @ 80 mph I can easily post 55 mpg. On longer trips @ 75 mph with bursts to 80/85 mph I posted 59 mpg and with multiple tank fulls. Normally I am just fine with 48 mpg, 584 miles in 6.25 hours.

Wow, that's not that good of mileage for that bike, or any crotch rocket for that matter, I'll have to ask my brother what he gets with his.. My bike is a 700lb cruiser and I consistently get 41-42mpg.. I usually get a little under 200 miles from a tank that holds about 5 gallons..

 

[Drivbiwire]

Come on, with only 25% thermal efficiency he's doing pretty good

 

[TDIJetta99]

LOL, I guess you could put it that way.. I know a carbureted Yamaha YZF600R can get mid-upper 40's if you keep out of the throttle.. The Fuel injected R6 can get up in the 50's.. Then again those are 600cc bikes too.. Mine is a fuel injected 1500cc twin and I usually get 40-42 with my normal riding style.. If I'm really nice to it I can wiggle 46mpg out of it, and a little more aggressive and it drops to 32-35mpg.. not too bad for an open-loop, speed density EFI with no oxygen sensors or anything.. it weighs 700lbs without me on it..

 

[darkhorse]

LOL, I guess you could put it that way.. I know a carbureted Yamaha YZF600R can get mid-upper 40's if you keep out of the throttle.. The Fuel injected R6 can get up in the 50's.. Then again those are 600cc bikes too.. Mine is a fuel injected 1500cc twin and I usually get 40-42 with my normal riding style.. If I'm really nice to it I can wiggle 46mpg out of it, and a little more aggressive and it drops to 32-35mpg.. not too bad for an open-loop, speed density EFI with no oxygen sensors or anything.. it weighs 700lbs without me on it..

Talk about efficiency: my Dodge/Cummins gets 1/2 the mileage with 10 times the weight.

 

[ruking]

Wow, that's not that good of mileage for that bike, or any crotch rocket for that matter, I'll have to ask my brother what he gets with his.. My bike is a 700lb cruiser and I consistently get 41-42mpg.. I usually get a little under 200 miles from a tank that holds about 5 gallons..

In light of the K& N filtering topic (vs oem as a sub title), knowing wha I know, I will continue to use oem type air filters on the TDI's. (I have been buying and using MANN air filters) I would guess the most IMPRESSIVE thing about this is how many (oem type MANN) air filters that I have NOT bought !!!??? 20/20 hind sight sez I have changed air filters WAY too often !! (I should be still on a second air filter)

The change in behavior has been going from 40,000 miles (oem recommended change intervals) to 60,000 miles intervals.

However, a further change (given dust conditions @ the dirty side of the air box) will be to 80,000 to 100,000 miles intervals.

I am not sure how to put this into perspective, but to say air filter changes have been made at 40k miles interval (oem recommendation obviously), @100,000 miles and the next is now due @ 180,000 miles- 200,000 miles (I am at 137,000 miles, or in another 43k miles or... so??!! )

So the interesting thing is a WHOLE lot of "hot air" has been passed for just 2 air filter changes and @ less than $12 a (current price) pop !!! . Again if people look at the VW TDI air box, (my op /ed: as butt UGLY as it IS!!) it is of intelligent design !! Again another reason why ya just gotta love VW TDI's !!! The only pesky thing is the 5,000 miles interval of cleaning the snorkel and screen. Dumping the "dirty side" of the non separated air box is simply a matter of turning the box 90 degrees.

The practical aspect cost per mile filtered (take your PICK !!??):

40,000 miles= .0003 cents
60,000 miles= .0002 cents
80,000 miles= .00015 cents
100,000 miles= .00012 cents

(using a current MANN price of $12. per filter)