[Vwdiesel] K&N Air Filters

[Gerry Wolfe]

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,