K & N

[chromeBuddha]

Sorry if I missed it, but didn't have the patience to read the entire encyclopedia/post...

Nobody here is attempting a blanket vilification of K&N. With a normally aspirated motor, the benifits of a free flowing intake are obvious to most... In the case of the TDI, this is tdiclub.com, the T handles that need. The turbo could, if so programmed, create more boost than it does. Headroom. What that headroom allows is a less free flowing intake which still supplies all the needed air to the motor.

So the issue isn't "is K&N bad" as much as "will a K&N filter provide a benifit to these engines". If the answer is no, then why bother debating further. Combine that with the many folks that have reported repeated MAF issues while using K&N filters... Yes, lot's of people have MAF issues anyway. Yes, it may be due to owner over-oiling...how is that to be prevented???

Why waste time arguing. If you want to use a K&N in your TDI, please do. But please don't encourage others to do something which provides no benifit and has a mountain of circumstantial testimony saying that it is detrimental.

This is my first diesel of any kind. I don't pretend to be an expert, but I have enough sense to see that the info in these threads is not enough to justify a blanket vilification of K&N.

dh

 

[WB9K]

Sorry if I missed it, but didn't have the patience to read the entire encyclopedia/post...

Nobody here is attempting a blanket vilification of K&N. With a normally aspirated motor, the benifits of a free flowing intake are obvious to most... In the case of the TDI, this is tdiclub.com, the T handles that need. The turbo could, if so programmed, create more boost than it does. Headroom. What that headroom allows is a less free flowing intake which still supplies all the needed air to the motor.

So the issue isn't "is K&N bad" as much as "will a K&N filter provide a benifit to these engines". If the answer is no, then why bother debating further. Combine that with the many folks that have reported repeated MAF issues while using K&N filters... Yes, lot's of people have MAF issues anyway. Yes, it may be due to owner over-oiling...how is that to be prevented???

Why waste time arguing. If you want to use a K&N in your TDI, please do. But please don't encourage others to do something which provides no benifit and has a mountain of circumstantial testimony saying that it is detrimental.

Hi Buddha,
This is the second thread I've been involved with on the subject, I'm new here. My first thread here was pretty much a timing question in which I mentioned in passing that I had put a K&N in my car, not realizing what a hot-button issue it is around here OR that it doesn't (apparently) seem to make any difference in a TDI. It HAS made a difference in many gassers I've owned, and without any apparent problems. That's about as strong as my advocacy has been. I never said "you should all be running K&N's in your TDIs" or anything like that. I HAVE asked for well-defined reasons as to why so many vehemently insist I should not and then attempted to poke holes in those reasons where I see possible thin spots--what else are we here for but a base of GOOD knowledge? I've been discouraged by some from using them in gassers in the past and mistakenly thought the debate here would be much the same. It is not.

Here's how I expect this to end for me at this point: I'll buy a paper filter this weekend (I hope I can find the time--the Buick needs a water pump and I'm doing house repairs too) and chart MAF numbers (and a few others) with my Vag-com while driving. If the numbers are the same for both filters (and I suspect they will be) I'll sell my slightly used K&N to a gasser on eBay and go back to paper. I'll post results here and handle the next newb that comes along with a K&N question. Maybe we can get a sticky together on the subject. I do understand how answering the same question over and over can get tiresome, and the search engine here won't turn up results for "K&N" unless you go into the advanced search engine.

dh

 

[Drivbiwire]

I suggest taking a Bosch course in these car systems to get you up to speed. This whole topic was beat to death back in 1996/7 starting with the release of the 1998 New Beetle.

 

[oilhammer]

Yeah, the concept of things like hot-film MAFs and planar wide-band Lambda sensors really seems to confuse a lot of people when they want to compare them to the old hot-wire MAF and the standard 1v oxygen sensors.

Bosch is at the cutting edge of this stuff, and in many cases the US consumer sees it for the first time in a Volkswagen. The '98 NB was a trendsetter. Toyota STILL does not have some of the same technology that VAG had in the late '90s

Unfortunately, that cutting edge tech usually carries with it some teething weaknesses that we tend to have to muddle through.

 

[ruking]

There is this very same discussion (oil filtered media) on the Corvette's and Z06 boards. In truth while designs might be radically different from say the TDI, the real questions remain similar( by virtue of air intake ingestion). Both run along the lines of whether or not the stock air filter flows and filters better or worse than oil filtered media. The bottom line is there is a tad bit of so called restriction due to the snow prophalatic designs which in theory limit the chances of hydro lock due to normal winter operation and/or in the worst case, hitting a 3 foot snow bank. There has been expensive dyno tests (75 per pull) indicating the stock air intake design IS more restrictive than say a $550 on up. blinged out air filter intake design!?

The most radical accidental discovery was to take off the stock air filter cover and/or drill holes in the air filter cover to increase the EXPOSED surface area and voila!!! The stock air filter flowed just as well as the much more expensive oil filtered media and/or blinged out air filter intake unit. Again this has been tested by dyno and road tests. Cost of the modification? ZERO!! Another example of the stock air filter flowing just fine and filtering better than oil filtered media.

Now the TDI has pretty much a little/no restrictive and elegant design. (snow prophalatic design is intergrated here in the TDI). If one is willing to forego the snow prophalactic design and in effect self insure with greater winter exposure to hydro lock, just remove the snorkel and operate the stock air box with the lower portions HUGE opening exposed to the air flow stream. You would still be getting the oem filter's superior filtration and cheaper at that.

But I will admit, to my eye the oem is "BUTT UGLY". However, " butt ugly" on the performance side is NOT correlated.

I follow Drivibiwire's recommendation (once installed) to NOT open/check the air filter SEAL. I run 60,000 mile intervals (oem recommendation of 40,000 miles) and am due a change at 120,000 miles (in 20,000 miles). I have checked the clean side of the intake several times and have used a hot soapy water cotton cloth to check for dirt, but it is-TOTALLY clean. The dirty side of the air box is predictably- DIRTY. In this case, I just tilt the un-opened air filter box to let the dirt out. I do also run the snorkel and clean the screen every 5,000 miles. It is always (predictably) dirty when I check it.

 

[otbBlaine]

Hi Buddha,
This is the second thread I've been involved with on the subject, I'm new here. My first thread here was pretty much a timing question in which I mentioned in passing that I had put a K&N in my car, not realizing what a hot-button issue it is around here OR that it doesn't (apparently) seem to make any difference in a TDI. It HAS made a difference in many gassers I've owned, and without any apparent problems. That's about as strong as my advocacy has been. I never said "you should all be running K&N's in your TDIs" or anything like that. I HAVE asked for well-defined reasons as to why so many vehemently insist I should not and then attempted to poke holes in those reasons where I see possible thin spots--what else are we here for but a base of GOOD knowledge? I've been discouraged by some from using them in gassers in the past and mistakenly thought the debate here would be much the same. It is not.

Here's how I expect this to end for me at this point: I'll buy a paper filter this weekend (I hope I can find the time--the Buick needs a water pump and I'm doing house repairs too) and chart MAF numbers (and a few others) with my Vag-com while driving. If the numbers are the same for both filters (and I suspect they will be) I'll sell my slightly used K&N to a gasser on eBay and go back to paper. I'll post results here and handle the next newb that comes along with a K&N question. Maybe we can get a sticky together on the subject. I do understand how answering the same question over and over can get tiresome, and the search engine here won't turn up results for "K&N" unless you go into the advanced search engine.

dh

it has already been done (FWIW, it did take me a while using the advance search to find it...and I even knew what I was looking for...)

http://www.bolhuijo.com/airflowtest/

 

[ruking]

it has already been done (FWIW, it did take me a while using the advance search to find it...and I even knew what I was looking for...)

http://www.bolhuijo.com/airflowtest/

Yes, a simple "SEARCH" done by WB9K, would have revealed a HUGE batch of clues!?

 

[otbBlaine]

True, but I wanted to find this test specifically; it essentially measures the restriction of each filter in inches of water...and the OEM filter comes out on top. It saves WB some time and effort, and puts the information in a location on the first page where other newbs will see it. It took me quite a long time when I first looked into the K&N subject to find that particular link...

 

[ruking]

True, but I wanted to find this test specifically; it essentially measures the restriction of each filter in inches of water...and the OEM filter comes out on top. It saves WB some time and effort, and puts the information in a location on the first page where other newbs will see it. It took me quite a long time when I first looked into the K&N subject to find that particular link...

Actually this will highlight the benefits of folks sharing on webs sites like TDICLUB.com. There is so much hidden in plain sight as to be almost ridiculous. The tool that measures air restriction is one example. Another (for brake fluid) is a 57 dollar tool that measures the (h2o) moisture content., moisture content strips another. Measuring actual operation of engine in hours, to match oil change intervals in hours. Oil analysis, the list goes on and on. Even the fact that VW (dumbs down) the specifications for timing belt parts......

 

[Drivbiwire]

Anybody that advocates anything other than a stock filter is clueless to how efficiecnt the OEM VW/Mann filters are. Unless you are pulling 25" WC (1.8" Hg vacume) you are wasting your time messing with the filters.

25" WC (1.8" Hg) is the point that the you should prepare for a filter replacement, any earlier and you are wasting your money, time and resources. I subscribe to 30" WC as the maximum for these motors.

Part number for the Manometer is on the gauge...You can order it from any CAT dealer. Also you will need a nipple and small o-ring to seal the unit to the airbox. This eliminates the guess work and tells you EXACTLY How much restriction your filter really has...

Filter box WITHOUT integral by-pass screen = 2-5" WC with a new "Cold Climate filter" (All previous generations of TDI)
Filter box WITH integral by-pass screen = 15" WC with a new "Cold Climate filter" (2004+)

Now Imagine this... Let's take the service idiots out of the equation and build a manometer directly into the MAF housing, then in the Service indicator software you have the ECU adjust your next service interval so that it computes how long the filter has until it needs replacing.

Since the ECU knows what the starting restriction was when the filter was new, It can plot an average rate of restriction accumulation and predict the next required service interval without any guess work!....just an idea for things to come

DB

 

[ruking]

Anybody that advocates anything other than a stock filter is clueless to how efficiecnt the OEM VW/Mann filters are. Unless you are pulling 25" WC (1.8" Hg vacume) you are wasting your time messing with the filters.

25" WC (1.8" Hg) is the point that the you should prepare for a filter replacement, any earlier and you are wasting your money, time and resources. I subscribe to 30" WC as the maximum for these motors.

Part number for the Manometer is on the gauge...You can order it from any CAT dealer. Also you will need a nipple and small o-ring to seal the unit to the airbox. This eliminates the guess work and tells you EXACTLY How much restriction your filter really has...

Filter box WITHOUT integral by-pass screen = 2-5" WC with a new "Cold Climate filter" (All previous generations of TDI)
Filter box WITH integral by-pass screen = 15" WC with a new "Cold Climate filter" (2004+)


DB

Since we are on the topic, at what mileage level does YOUR gauge trigger close to 30 WC?

 

[Drivbiwire]

I usually replace at 25", last filter was replaced after 65,000 miles. Keep in mind I live in the desert with plenty of dust...Most would consider my conditions "severe"

DB

 

[andreigbs]

So then the OEM recommended interval of 40K is conservative, taking into account severe conditions that many folks won't see. I know some folks who change air filters every other oil change, and every oil change a 5k. I keep referring them to this site. Thanks to all for the enlightenment and potential ammo I now have.

 

[ruking]

I usually replace at 25", last filter was replaced after 65,000 miles. Keep in mind I live in the desert with plenty of dust...Most would consider my conditions "severe"

DB

Well with air filter change at 60,000 miles in an "urban area" with an oem recommendation of 40,000 miles, that makes me a belt and suspenders kind of guy! 65,000 miles or bust! (That will put me at 125,000 miles)

 

[Drivbiwire]

FWIW, the Mercedes CDI air filter (3.2L, 6-cylinder 200hp/380ft-lbs) is 25% smaller in total area than the TDI's air filter (1.9L 90-105hp, 175ft-lbs) and the CDI has an estimated change interval of 56,000 miles...Of course that depends on the measured restriction of the filter. So far I don't know of anyone that has had to replace the CDI filter early regardless of conditions.

DB

 

[ruking]

FWIW, the Mercedes CDI air filter (3.2L, 6-cylinder 200hp/380ft-lbs) is 25% smaller in total area than the TDI's air filter (1.9L 90-105hp, 175ft-lbs) and the CDI has an estimated change interval of 56,000 miles...Of course that depends on the measured restriction of the filter. So far I don't know of anyone that has had to replace the CDI filter early regardless of conditions.

DB

As I remember when I changed the air filter out at 60,000 miles, part of my take after I had " broken the seal" by unscrewing the top assembly and taking a hard look was: why was I even bothering. Sure the dirty side of the filter was dirty, but the filter was in terrific shape,, with NO dirt on the clean side. I suspect/swag when I change this at (now) 65,000 miles, it will essentially look like it did when I changed the first one at 60,000 miles. Seems like the quality (and subsequent over kill ) is built into the VW oem/Mann air filters!

 

[WB9K]

Uh....?

it has already been done (FWIW, it did take me a while using the advance search to find it...and I even knew what I was looking for...)

http://www.bolhuijo.com/airflowtest/

Is this the link you actually intended to post? This is nothing at all like test I was describing, and not using TDI parts to boot. I appreciate the effort, but if what I was talking about has indeed been done and posted on the web, this isn't it.

dh

 

[otbBlaine]

Is this the link you actually intended to post? This is nothing at all like test I was describing, and not using TDI parts to boot. I appreciate the effort, but if what I was talking about has indeed been done and posted on the web, this isn't it.

dh

Actually, it is . You wanted to compare the flow rates between the two different filter elements, and this test uses measured vacuum in inches of water to determine exactly that. Whether or not TDI parts are used is completley moot; I'm quite sure that the physics behind ductwork don't change depending on what type of fuel your vehicle uses (this test is a very good indication of diesel performance, however- if you don't know why, I'm happy to explain it). Your test involves an electronic reading from your MAF sensor, this is a physical reading made with human eyes. The setup is different, sure, but the ultimate goal of each test is the same, to determine whether or not a k&n air filter really out flows an OEM filter. In this test, the OEM paper element filter came out on top.

 

[WB9K]

Actually, it is . You wanted to compare the flow rates between the two different filter elements, and this test uses measured vacuum in inches of water to determine exactly that. Whether or not TDI parts are used is completley moot; I'm quite sure that the physics behind ductwork don't change depending on what type of fuel your vehicle uses (this test is a very good indication of diesel performance, however- if you don't know why, I'm happy to explain it). Your test involves an electronic reading from your MAF sensor, this is a physical reading made with human eyes. The setup is different, sure, but the ultimate goal of each test is the same, to determine whether or not a k&n air filter really out flows an OEM filter. In this test, the OEM paper element filter came out on top.

Well, I can show you a couple independent tests where the K&N outflows everything. I can show you at least one independent test where three different paper filters (not Fram) filtered visibly differently (that's the one linked earlier in this thread by Whitedog). Perhaps more relevant to the specific link at hand, here is the abstract of an experiment conducted by Harvard's fluid mechanics dept which found that airbox and intake system geometry can in fact have a profound impact on system airflow independent of the filter. I posted this last week in another thread, but nobody appears to have bothered to read it.

http://adsabs.harvard.edu/abs/1996APS..DFD..EG04C

I find a controlled lab study that actually used different airboxes and measured the results with laser sensors more credible than some guy in his garage with a leaf blower and parts store measuring tools augmented by some other guy on the internet who says that's all I need to know. I'm getting a little tired of being lectured about "not doing my homework" only to have tests and posts paraded before me that simply do not prove what people claim they do.

The best suggestion made so far IMO, is DieselOx's suggestion to use VAG-com to take airflow measurements in the actual car of interest with the filters of interest. This is the most valid apples-to-apples test practicable without the use of VERY expensive equipment which has been suggested here so far that I have seen.

I strongly suspect at this point that the results of the VAG-com test will be what everyone is predicting here. However, with all due respect, that leaf-blower test doesn't prove it, not by a longshot.

dh

 

[whitedog]

dh, until you reminded me about those links, i had forgotten to look at them. The reason I didn't look the first time was that they were just the address and not an actual hyperlink.

I am betting that others did the same thing since we are mostly lazy creatures.

 

[rdkern]

I resemble that remark!

 

[Dale Seiler]

DBW and others on this thread,

First I would like to apologize to all, especially to DBW for my lack of understanding and quick rush to judgment. I did not understand the facts and did say some pretty nasty things in counter point. For this I am truly sorry and will learn to listen more and write less.
I have run K&N filters in most of my vehicles and did count on K&N to have their facts straight about air flow to the engine. I have not had any of the problems that DBW brought to the table. I looked at pictures of a clearly neglected K&N filter and assumed that it was an attempt by him to just discredit the filter.
After reading the test data and charts presented by DBW and others, especially the leaf blower test. I am convinced that I was clearly out of line and looked like a fool to all of you.
I was going to put the K&N filters into our two new TDI's but after the expert documentation by DBW on the damage that can be done to the MAF sensor I have changed my mind.
I think DBW's idea of the manometer install into the clean air box is a good one and plan on doing that retro fit. I do work directly with the Cat dealer here in Denver and will order two manometers tomorrow.

In closing,
DBW, I am sorry for my misguided comments. I have come to respect your intense research and genuine interest in sharing it with others.

regards

 

[whitedog]

DBW and others on this thread,

First I would like to apologize to all, especially to DBW for my lack of understanding and quick rush to judgment. I did not understand the facts and did say some pretty nasty things in counter point. For this I am truly sorry and will learn to listen more and write less.
I have run K&N filters in most of my vehicles and did count on K&N to have their facts straight about air flow to the engine. I have not had any of the problems that DBW brought to the table. I looked at pictures of a clearly neglected K&N filter and assumed that it was an attempt by him to just discredit the filter.
After reading the test data and charts presented by DBW and others, especially the leaf blower test. I am convinced that I was clearly out of line and looked like a fool to all of you.
I was going to put the K&N filters into our two new TDI's but after the expert documentation by DBW on the damage that can be done to the MAF sensor I have changed my mind.
I think DBW's idea of the manometer install into the clean air box is a good one and plan on doing that retro fit. I do work directly with the Cat dealer here in Denver and will order two manometers tomorrow.

In closing,
DBW, I am sorry for my misguided comments. I have come to respect your intense research and genuine interest in sharing it with others.

regards

*** puts the popcorn away...***

 

[ruking]

It took a lot of gumption to write what you wrote!! I salute you!

 

[TornadoRed]

Gee, I wish I had a 30" monitor so I could read this thread.

 

[otbBlaine]

Well, I can show you a couple independent tests where the K&N outflows everything. I can show you at least one independent test where three different paper filters (not Fram) filtered visibly differently (that's the one linked earlier in this thread by Whitedog). Perhaps more relevant to the specific link at hand, here is the abstract of an experiment conducted by Harvard's fluid mechanics dept which found that airbox and intake system geometry can in fact have a profound impact on system airflow independent of the filter. I posted this last week in another thread, but nobody appears to have bothered to read it.

http://adsabs.harvard.edu/abs/1996APS..DFD..EG04C

I find a controlled lab study that actually used different airboxes and measured the results with laser sensors more credible than some guy in his garage with a leaf blower and parts store measuring tools augmented by some other guy on the internet who says that's all I need to know. I'm getting a little tired of being lectured about "not doing my homework" only to have tests and posts paraded before me that simply do not prove what people claim they do.

The best suggestion made so far IMO, is DieselOx's suggestion to use VAG-com to take airflow measurements in the actual car of interest with the filters of interest. This is the most valid apples-to-apples test practicable without the use of VERY expensive equipment which has been suggested here so far that I have seen.

I strongly suspect at this point that the results of the VAG-com test will be what everyone is predicting here. However, with all due respect, that leaf-blower test doesn't prove it, not by a longshot.

dh

I started a really long response, but here are my major beefs with your post.

1. I can say that I found a study that the moon is made of cheese...that doesn't mean that it really is. See #4.

2. With regards to the abstract (not even the whole paper ), you missed my point; filters HAVE to be evaluated seperately from intake systems in order to isolate the parameters in question. You don't even know exactly what the experiement did because there is no procedure section available so that someone like me could duplicate it. Please post full papers or nothing as this link is essentially useless to me (nothing I didn't know already). I would be willing to bet a large amount of money that one type of filter media was used in the entire experiement (the tip-off is in the first sentence, no less).

3. Also, whether or not a test uses the latest technology or not doesn't matter as long as the math works and the measurements are taken with enough accuracy and consistency to minimize error in the results. Laser Doppler anemometers are cool, but you don't need them to find out if one type of air filter out performs another.

4. I read your other links; one measured horespower increase and filtering ability, the other just filtering ability. NOT ONE of the links you posted had the k&n come out on top, in flow or in filtering performance. Thank you for making my point (well, our point) valid with your links, and for shooting holes in your argument. I didn't even have to work at it.

I use glorified leaf blowers all the time to measure things like airfoil performance and pressure drop through ducting; they work just fine for pulling air.

Dale: dittos on what ruking said. Way to step up.

 

[wjdell]

I removed a K&N from a chevy truck last year - held up in the light - and I was stunned. Almost disbelief that anyone would use this for prolonged street use. The companys who make injectors must pay K&N. I could see someone wanting to use on race day, but remove it before heading home on the street.

 

[Richard55]

What is the % of MAF sensors going bad that do no have K&n filters installed, 90-95 % or is it much higher. Logic stock filters make MAF sensors go bad.

 

[oilhammer]

What is the % of MAF sensors going bad that do no have K&n filters installed, 90-95 % or is it much higher. Logic stock filters make MAF sensors go bad.

The hot-film MAF is a somewhat delicate design anyways (see my earlier post on the down-side of cutting edge technology). So many of the earlier Bosch units did indeed fail all on their own. So much so, that there were TSBs, recalls, extended warranties, etc. Granted most of these were on the 2.0L cars, but the MAF is essentially the same design.

Any compromise to an already delicate design only creates more problems. Be it a poor-fitting paper filter or an oiled filter, makes no difference, it still compromises the design.

The OE Mann-supplied paper air filters are VERY good and fit VERY well. Time and time again we've seen they work just fine, and there is really no need to mess with changing to something else, even with other modifications for increased output. The 240hp R32 uses the SAME FILTER!!!

 

[tditom]

DBW and others on this thread,

First I would like to apologize to all, especially to DBW for my lack of understanding and quick rush to judgment. I did not understand the facts and did say some pretty nasty things in counter point. For this I am truly sorry and will learn to listen more and write less.
I have run K&N filters in most of my vehicles and did count on K&N to have their facts straight about air flow to the engine. I have not had any of the problems that DBW brought to the table. I looked at pictures of a clearly neglected K&N filter and assumed that it was an attempt by him to just discredit the filter.
After reading the test data and charts presented by DBW and others, especially the leaf blower test. I am convinced that I was clearly out of line and looked like a fool to all of you.
I was going to put the K&N filters into our two new TDI's but after the expert documentation by DBW on the damage that can be done to the MAF sensor I have changed my mind.
I think DBW's idea of the manometer install into the clean air box is a good one and plan on doing that retro fit. I do work directly with the Cat dealer here in Denver and will order two manometers tomorrow.

In closing,
DBW, I am sorry for my misguided comments. I have come to respect your intense research and genuine interest in sharing it with others.

regards

way to man-up, dude!! This is a rare occurrence and I'm impressed. I'm glad I didn't rush to put you on the ignore list .

... I ...will learn to listen more and write less.

this very good advice that most of us should do more of.