[Vwdiesel] K&N Air Filters

Thu Aug 4 16:09:18 PDT 2011

Good link Tad.
My own practical experience with k&N follows.
89 jetta td.
I tried one because while, or following pounding drifts in winter, the stock filter would get soft, and collapse, which is pretty annoying.
So, I purchased one, installed it, and carried on as usual.  When doing some maintenance, I noticed that the leading edges of the turbo wheel had FOD, and did not have any before.  It was VERY minor, but FOD nonetheless. (foreign object damage)  So, rather than scream and point at the filter like an idiot with a sample size of one, I figured I should at least be an informed idiot with a sample size of one.  
I greased the intake tube post filter of my jetta with a very water resistant grease (srs3000)  It stays very tacky...   After a summer, I pulled the lot apart again, and examined the intake tract.  There was no discernable dust under magnification, BUT there was an alarmingly large number of small sand particles.  I suspect the grit had enough energy to penetrate the cotton gauze that holds the filtration media in the airflow.  In the K&N, the filtration media is oil by the way, not the cotton gauze.  The gauze just holds the oil in place. The cotton was well oiled, it was virtually new, no damage from improper cleaning, etc...
So, I do the same grease job to the 6.5 banks turbo conversion with a k$N on Dad's truck.  Same deal.
And to my race car.  Same deal.  On the race car (street stock chevy 350 dirt car), I put a foam outer sock, made by I think K&N, around the outside with the intent of diffusing the airflow, and that fixed the problem, confirming what I thought was at work.  That if a small grain size piece of sand had enough momentum, it would penetrate the cotton matrix too fast for the oil filtration media to hold it in place. Bigger sand and fine dust would get halted, but not the correct size particulates.
Admittedly, on the stock car, buzzing along at 6400 at the end of the straight, dirt injestion is NOT a concern, it gets a rebuild before that is ever an issue... but on a high mile car, especially a turbo where air cleanliness is absolutely critical, I would suggest K$N may have their own interests at heart, not yours.  On a N/A, if you change your oil regularly, I doubt it matters that much, and if you believe it works, and has more power, that's great, but here are better filters than a K$N by a long shot.
-James

-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On Behalf Of Tad
Sent: August-04-11 4:02 PM
To: Gerry Wolfe
Cc: vwdiesel at vwfans.com
Subject: Re: [Vwdiesel] K&N Air Filters

I don't want to start a war, but lets make up our minds with data from an
unbiased source.

Here's a guy who put a lot of work into testing various filters and
gathering specs:
http://home.roadrunner.com/~jbplock/ISO5011/SPICER.htm

The AC Delco filter test ran for 60 minutes before exceeding the restriction
limit while the AMSOIL and K&N tests each ran for 20 and 24 minutes
respectively before reaching max restriction. In 60 minutes the AC Filter
accumulated 574gms of dirt and passed only 0.4gms. After only 24 minutes the
K&N had accumulated 221gms of dirt but passed 7.0gms. Compared to the AC,
the K&N� �plugged up� nearly 3 times faster, passed 18 times more dirt and
captured 37% less dirt.

One important point to note - while the washable foam filters had the lowest
restriction initially, they held the least dirt and therefore clogged faster
than the other filters.  Once clogged, they resisted flow about as much as
the other filters when fully loaded.

The author wrote: "*Now that I am not doing the tests and my objectivity is
not necessary, let me explain my motivation. The reason I started this
crusade was that I was seeing people spend a lot of money on aftermarket
filters based on the word of a salesperson or based on the misleading,
incomplete or outright deceiving information printed on boxes and in sales
literature. Gentlemen and Ladies, Marketing and the lure of profit is VERY
POWERFUL! It is amazing how many people believe that better airflow = more
power! Unless you have modifications out the wazoo, a more porous filter
will just dirty your oil! Some will say " I have used aftermarket brand X
for XXX # years with no problems. The PROBLEM is you spent a chunk of ching
on a product that not only DID NOT increase your horsepower, but also let in
a lot of dirt while doing it! Now how much is a lot? ANY MORE THAN NECESSARY
is TOO MUCH! "*
*
*
I also feel the need to point out the following  from K&N: "a square inch of
our filtration medium will flow 200 or even 300% more air": this is not an
apples-to-apples comparison, because paper filters contain a much larger
area of filtration material - they are pleated!

However... given all that - it's also true that a K&N probably filters "good
enough".  It's uncommon for engines to fail due to wear anyway - typically
something else will take them out long before internal components "wear
out".

>From my own personal experience - when my car was new I got suckered by the
marketing hype and started using an oiled foam filter  (Pipercross).  After
my MAF failed for the FOURTH time, the dealer insisted I change back to
paper.  Not long after that I did an oil analysis that showed the dirt (Si)
level in my oil was among the HIGHEST THEY HAD EVER SEEN.  When I had my
T-belt changed, the mechanic noted that the intake tract felt "sandy".

I'm now at over 10 years and 170k miles later, and still no apparent ill
effects from all that dirt.  But did it increase the wear of my engine? I'm
sure it did...

So yeah, a K&N flows better (at first), but it's not going to produce any
meaningful results other than a hole in your wallet and more dirt in your
oil.

Besides, washing those things is a huge pain in the ass! :)

On Thu, Aug 4, 2011 at 2:00 PM, Gerry Wolfe <GerryWolfe at shaw.ca> wrote:

> I tend to base my opinions on first-hand experience and specifications, not
> on hearsay and anecdotal / third-hand comments.
>
>
>
> Here is an excerpt from the K&N website: Here is the url:
> http://www.knfilters.com/audio/audio_book_mp3.htm
>
>
>
> Filtration:
>
> ".There is only one generally accepted standard test procedure and that is
> the ISO 5011 protocol. K&N Air Filters tested generally range between 95%
> and 99% in overall efficiency using coarse test dust. These numbers are
> very
> similar to quality standard disposable air filters we have tested over the
> years. We have tested a lot of air filters and seen results as low as 90%
> and as high as 99%. While there is no published research we have been able
> to locate on the relationship between engine wear and either particle size
> or air filter efficiency, our experience is a K&N Air Filter, like most
> disposable air filters, will provide all the protection an engine will need
> under normal operating conditions."
>
> Air Flow:
>
> ".follow a protocol that had been established for measuring the flow rates
> of cylinder heads and carburetors at a constant rate of restriction. We use
> a flow bench and increase the rate of airflow until restriction equals a
> pressure drop sufficient to displace 1.5 inches of a consistent quantity of
> water. Our filters flow substantially more air than a disposable air
> filter.
> a square inch of our filtration medium will flow 200 or even 300% more air
> than a standard disposable filtration medium. When translated into an
> actual
> air filter, this often means a K&N will flow as much as 30% to 70% more
> air."
>
>
>
> I have used K&N filters since they came out about 40 years ago, and know
> others who have also used them.  I have never seen or heard of any
> excessive
> wear issues.  My last vehicle ('91 Jetta TD) had K&N since new, and had a
> head gasket replaced at 275K km (also rebuilt the head and rehoned /
> re-ringed).  There was no sign of internal wear, not even a lip built up in
> the cylinder.  Even main bearings could have been re-used.  IMHO, this
> indicates pretty good filtration, and it's good enough for me.
>
>
>
> Rgds, g.
>
>
>
> From: Stephen Kraus [mailto:ub3ratl4sf00 at gmail.com]
> Sent: Thursday, August 04, 2011 10:13 AM
> To: pmdolan at sasktel.net
> Cc: vwdiesel at vwfans.com; Gerry Wolfe
> Subject: Re: [Vwdiesel] 2.5
>
>
>
> Just to chime in to confirm what pmdolan said:
>
>
>
> K&N is not a good air filter for diesel, it can harm them as the diesel
> pull
> MUCH more air than a gas engine (I wouldn't use K&N on a gasser either...)
>
>
>
> I've had to repair a couple TDIs and 1.6ls that ingested dirt through the
> filter. K&N IS high airflow, but they do so by sacrifcing filtering
> quality.
>
> On Thu, Aug 4, 2011 at 10:49 AM, <pmdolan at sasktel.net> wrote:
>
> Not trying to be snotty,but why would you put an K&N air filter in a VW (or
> much of anything else for that matter)???
>
> I assume you believe their advertising - which is pure BS.  There is a
> mountain of experience with many vehicles that shows these things do
> precious little to remove anything smaller than a turkey from the airstream
> and don't really flow all that well.  Don't know about MkIII, but for MkIV,
> the stock airbox and filter will handle WAY more air than the engine needs
> to at least 200HP and filter properly.  Since you live in paradise, if you
> stick to the main roads it won't be that much of a problem, but if you ever
> go near any dirt of any kind, you will be removing it from the air with
> your
> engine, not the air cleaner.
> On Thu, 4 Aug 2011 09:17:12 -0700, Gerry Wolfe wrote:
> I have a '97 Jetta with TDI. Replaced the stock with 2.5" all the way thru,
>
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