[xj] K & N Air Filters

I have had a bit of trouble the last few times I went to
change out my air filter. The part had to be special
ordered. One place quoted $25 !!! One $15, which is pretty
much in the ball park.

I decided to get a K & N filter not for their claim of
better horsepower, but since it is washable and reusable.

Any comments on this?

As an aside, I ran up the road with the front of the air
filter off, just a mile or two into town. The filter was
still in place. I just figured, the filter’s still in, I
need a new one, and its a short ride, shouldn’t be any
problem to the car. It was pretty funny, it sounded either
like a big muscle car, or an exhaust leak. Pretty funny for
an old Jag to sound like that.–
Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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I have just one question about K&N filters: if more air gets through,
logic suggests that more dirt gets through, no?

Gregory-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org] On Behalf
Of 1985vdp
Sent: January 23, 2006 5:07 PM
To: xj@jag-lovers.org
Subject: [xj] K & N Air Filters

I have had a bit of trouble the last few times I went to
change out my air filter. The part had to be special
ordered. One place quoted $25 !!! One $15, which is pretty
much in the ball park.

I decided to get a K & N filter not for their claim of
better horsepower, but since it is washable and reusable.

Any comments on this?

===================================================
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I might be able to offer a helpful comment on this one.

Filters as used for air, fuel, and oil use a ‘depth capture’ mechanism -
like a sponge. As such it isn’t helpful to think of them as a strainer,
where everything above the mesh size gets caught, and everything smaller
gets through.

When assessing a filter the type/quality of the ‘media’, its surface area,
and the fluid velocity determines the % of particles that get through of any
given size. So for a cellulose (paper) element you may find that at low
engine power levels 99% of 10um particles are trapped, whereas at high
speeds only 90% get trapped. If the element is heavily restricted the
effective surface area is reduced, and so the particles tend to extrude
through more readily, while at the same time seeing a higher pressure drop
across the element.

The benefit of using a quality element is that the pressure drop is lower,
hence the air downstream is denser resulting in greater potential power. The
reduced pressure drop is due to a combination of superior media (e.g. micro
glass fibres), and greater surface area, so the effectiveness of capture
will likely be better not worse.

In hydraulic systems we often install grossly oversized filters - the system
stays medically clean, the filters never need changing, and the rest of the
system receives better protection. Filters cost more, however.

When I fist bought my S1 14 years ago, it would go through fuel filters
every 3-6 months. SO I tossed out the pathetic little cotton thimble beasty
in the boot, and installed a hydraulic standard filter with at least 10
times the area. I think I have changed it once since - because I thought I
should rather than because it needed it.

An item of total trivia that may amuse some of you is how hydraulic filters
are tested for affectiveness according to an international standard. A
special dust is mixed with fluid and passed through the filter under
controlled conditions and measurement. The dust comes from a special part of
the desert in Arizona, becuase the particle size distribution perfectly
suits the test…

Regards

Ian Duncan, Wollongong Australia.
'71 S1XJ6 with 350&T400.
'77 XJC6 being restored.-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org]On Behalf
Of Dr. Gregory Andrachuk
Sent: Tuesday, 24 January 2006 1:34 PM
To: ‘1985vdp’; xj@jag-lovers.org
Subject: RE: [xj] K & N Air Filters

I have just one question about K&N filters: if more air gets through,
logic suggests that more dirt gets through, no?

Gregory

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I’ve been driving without the front of the ‘can’ and the ‘trumpet’ for over
2 years now. Better mileage for one thing. Only downside is in hot weather
and/or slow traffic it sucks in a bit more hot air than I’d like. I’m
working on a cold air intake that fits into the narrow gap next to the
radiator.

As for the ‘growl’, I’ve grown to rather like the sonorous note that occurs
when I push the pedal in a bit.

Fazal----- Original Message -----
From: “1985vdp” davewilliamson2@verizon.net

As an aside, I ran up the road with the front of the air
filter off, just a mile or two into town. The filter was
still in place. I just figured, the filter’s still in, I
need a new one, and its a short ride, shouldn’t be any
problem to the car. It was pretty funny, it sounded either
like a big muscle car, or an exhaust leak. Pretty funny for
an old Jag to sound like that.

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I think it’s Alex Cannara (he can confirm or deny) who drives without the
horn-like front end of the air filter installed all of the time.

BT-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org]On Behalf Of
1985vdp
Sent: Monday, January 23, 2006 8:07 PM
To: xj@jag-lovers.org
Subject: [xj] K & N Air Filters

As an aside, I ran up the road with the front of the air
filter off, just a mile or two into town. The filter was
still in place. I just figured, the filter’s still in, I
need a new one, and its a short ride, shouldn’t be any
problem to the car. It was pretty funny, it sounded either
like a big muscle car, or an exhaust leak. Pretty funny for
an old Jag to sound like that.

Dave Williamson 85 XJ6 VDP ‘Black Beauty’

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In reply to a message from Fazal Cader sent Tue 24 Jan 2006:

Not necessarily as far as more air=less filtration.

Some filter elements are more efficient, and allow more air
to flow through them, while still filtering enough to be safe.

I suppose maybe I should check micron filtration size if I
really want to. I did work with filters in the past, of
varying types, and am aware of pressure drops, etc… My
profession at the time was in the field of environmental
testing. We basically sucked effluent through filters and
chemicals to figure out how much pollution there was,
incorporating flow rates and pressure drops on the calculations.

People have been using these filters on muscle cars for
years, and those sort of folks are pretty fussy about their
machines. I would expect the K&N filter is perfectly
adequate, and the extra air flow is probably going to help
the engine.–
Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
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In reply to a message from 1985vdp sent Tue 24 Jan 2006:

Ok, I did find this.

97-99% efficient on a wide range of micron sizes, 5.5 being
the smallest.

Thats pretty darn small, so to me its fine.

I couldn’t find info on your standard cellulose filter, but
I would suspect its at least equal, but possibly worse given
the price.–
Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
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There is fellow on the E Type list who has done extensive testing on
K&N’s. He’s an ex Jaguar mechanic and had his own race team for a while,
so did a lot of dyno testing with K&N’s installed versus the standard
air filter. He found that at 5500 RPM it made exactly 1 hp difference,
and in the lower rev ranges the standard air filter was actually superior.On his race cars, he outfitted one car with a K&N, and another with the standard air filter and measured the bores at the start of the season. Near the end of the season he measured again, and found the car with the K&N had significantly more bore wear than the standard car. In his words the K&N only stopped “boulders” from coming into the engine. Personally, I stick with the OEM filter. Craig 92 VDP 1985vdp wrote:

I have had a bit of trouble the last few times I went to
change out my air filter. The part had to be special
ordered. One place quoted $25 !!! One $15, which is pretty
much in the ball park.

I decided to get a K & N filter not for their claim of
better horsepower, but since it is washable and reusable.

Any comments on this?

===================================================
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In reply to a message from Craig Talbot sent Tue 24 Jan 2006:

Good to hear the feedback, especially since I usually run no
more than 3000 rpm.

Mine is probably going back in the mail in light of this.
So I will have to hunt them down and wait a bit, maybe I
will buy them in sets of two.–
Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
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In reply to a message from 1985vdp sent Tue 24 Jan 2006:

You had to ask. :=)

http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm--
The original message included these comments:

Mine is probably going back in the mail in light of this.


Cheers, Tom 1978 SII XJ6LFI 1996 Dodge/Cummins 2500
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In reply to a message from Rowdy III sent Tue 24 Jan 2006:

Very interesting but even a K&N will stop more than an open
trumpet & if you are running carbs the fuel washdown from
the AED will cause more engine bore wear than the crappiest
filter.So we need a redesigned less restrictive inlet duct
feeding a good quality standard filter element & keep it
dry/free of oil.–
The original message included these comments:

In reply to a message from 1985vdp sent Tue 24 Jan 2006:
You had to ask. :=)
http://home.usadatanet.net/~jbplock/ISO5011/SPICER.htm


Keith Turner '79 XJ6 based Aristocat, , '81 3.4 XJ6
Swansea, United Kingdom
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In reply to a message from 1985vdp sent Tue 24 Jan 2006:

Back in the mail it goes.

Thanks for the help. My quantitative thoughts were put to
rest with the last post.–
Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
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Ian,

So is your opinion that this type of filter ok or not ?

It is a cotton/mesh/oil impregnated type. Seems good in principle, moist
oil should trap dust. I don’t live in a dusty area, and 80% of my mileage
is highway. The filter I got ‘looks’ to have very much less filter element,
thus less surface area, and maybe less filter efficiency ???

I’m aware of principles of pressure drop flow rates etc, but things get
funny once you reach critical flow rate. I have no idea if a
cellulose/paper filter ever reaches critical, so I am confused as to the
comparison. One individual on the list made a comparison to the filter
being a ‘boulder trap’ but they are running at 5000+ rpm and racing. I’m
looking at everday driving at no more than 3000 rpm on average, a few bursts
of speed are insignificant.

I’ve worked around filters before in other industry and know about the
micron size/capture principle. IMO, the best way to make a comparison is to
get an idea of the pressure drop at ‘normal’ driving speeds through both
filters. K&N boasts (and one cannot be sure of manufacturers claims) good
filtration rates across a wide range of micron sizes. In my rough
perspective of understanding particle size, 5.5 micron (the lowest on the
list) is fine.

Back in my days of industrial pollution testing, we were concerned with
primarily micron sizes below 10 microns, the typical industrial effluent
size. But… where dose one factor that in ??

My conclusion is… I live in a fairly industrialized area, a lot of big
industry around, coal fired power plants, various industries belching their
pollutants. Particulate, NOx, SO2, and who knows what else. Most of the
particulate in my region is not the large stuff, so according to K&N’s
charts, they claim a pretty good efficiency.

I don’t feel too bad about using the filter, but am persuaded to delve back
a little further into my environmental engineering days to get a
quantitative look. Each region presents itself with different particulate
sizes, and I am far from racing my car.

Dave----- Original Message -----
From: “Ian and Kathryn” ianandkathryn@optusnet.com.au
To: “Dr. Gregory Andrachuk” v12-vdp@shaw.ca; “‘1985vdp’”
<@1985vdp>; xj@jag-lovers.org
Sent: Tuesday, January 24, 2006 5:13 AM
Subject: RE: [xj] K & N Air Filters

I might be able to offer a helpful comment on this one.

Filters as used for air, fuel, and oil use a ‘depth capture’ mechanism -
like a sponge. As such it isn’t helpful to think of them as a strainer,
where everything above the mesh size gets caught, and everything smaller
gets through.

When assessing a filter the type/quality of the ‘media’, its surface area,
and the fluid velocity determines the % of particles that get through of
any
given size. So for a cellulose (paper) element you may find that at low
engine power levels 99% of 10um particles are trapped, whereas at high
speeds only 90% get trapped. If the element is heavily restricted the
effective surface area is reduced, and so the particles tend to extrude
through more readily, while at the same time seeing a higher pressure drop
across the element.

The benefit of using a quality element is that the pressure drop is lower,
hence the air downstream is denser resulting in greater potential power.
The
reduced pressure drop is due to a combination of superior media (e.g.
micro
glass fibres), and greater surface area, so the effectiveness of capture
will likely be better not worse.

In hydraulic systems we often install grossly oversized filters - the
system
stays medically clean, the filters never need changing, and the rest of
the
system receives better protection. Filters cost more, however.

When I fist bought my S1 14 years ago, it would go through fuel filters
every 3-6 months. SO I tossed out the pathetic little cotton thimble
beasty
in the boot, and installed a hydraulic standard filter with at least 10
times the area. I think I have changed it once since - because I thought I
should rather than because it needed it.

An item of total trivia that may amuse some of you is how hydraulic
filters
are tested for affectiveness according to an international standard. A
special dust is mixed with fluid and passed through the filter under
controlled conditions and measurement. The dust comes from a special part
of
the desert in Arizona, becuase the particle size distribution perfectly
suits the test…

Regards

Ian Duncan, Wollongong Australia.
'71 S1XJ6 with 350&T400.
'77 XJC6 being restored.

-----Original Message-----
From: owner-xj@jag-lovers.org [mailto:owner-xj@jag-lovers.org]On Behalf
Of Dr. Gregory Andrachuk
Sent: Tuesday, 24 January 2006 1:34 PM
To: ‘1985vdp’; xj@jag-lovers.org
Subject: RE: [xj] K & N Air Filters

I have just one question about K&N filters: if more air gets through,
logic suggests that more dirt gets through, no?

Gregory

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In reply to a message from DAVE WILLIAMSON sent Wed 25 Jan 2006:

May I be allowed to throw some
gasoline on the fire?

Does additional(less constricted)
breathability (is that a word?) guarantee
increased performance (HP) in a
4.2L engine utilizing the Bosch/Lucas
L-jetronic fuel injection system.

I am curious if it does. Has anyone
dyno tested and established results
utilizing a K&N air filter -vs- a stock
air filter?

I am tempted to suggest there would be
negliable difference between the two,
however before I open yap and insert
foot, has anyone discussed/looked into
this before?

Best Regards,

Kirk Yonker
85 Jaguar XJ6 S3 (Fed. Spec)
Seattle–
Wedgepig
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Yep, works great (when the cars are working :). The SII has a large intake
which goes over the rad, so is better anyway. I’ll be changing that a bit
some day, to get the cross section larger and match the 3" pipe to the filter
(the S3’ filter front has a small opening). Our S3 is getting an S2 filter
can also because it actually has mounting bracket that bolts to the fender
wall (and our S3 still has the threaded holes for it).–
Alex
79xj6L SII (BRG + wires)
86xj6 SIII (Black)
61 Sprite MkII (Red)
Menlo Park, Calif.

Bill Thom wrote:

I think it’s Alex Cannara (he can confirm or deny) who drives without the
horn-like front end of the air filter installed all of the time.

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I’ve been using K&Ns on my Jags. No power increase on the XJ6, perhaps a
small increase on the XJS. Reusability is a nice feature.

As far as filtering and engine life goes, I think we are, excuse the
terminology, picking fly sh*t out of the pepper. I’ve had the K&Ns on my XJ6
for 7 or 8 years …about 60K miles. If something awful was gonna happen I
think I would have noticed by now. As it is the engine runs like a watch and
uses no oil at 143K miles. From my own experience I am hard pressed to say
that a K&N is significantly or even minutely sub-par. Nor can I say it is
particularly above-par.

This reminds me a bit of oil comparisons…we’ve all read 'em, here and
elsewhere. Brand “X” with .0001345 % ash content is great, but brand “Y”
with .0001349 % ash content is gonna ruin your motor. Oil filters, too. Heh
heh heh. On one old Buick that had been in the family for ages I started
using the cheapest oil filters (usually the much maligned Fram) and oil I
could find at about 120K miles. At 220K miles we sold it and it still
“purred like a tomcat in a dairy”. :slight_smile:

It’s all interesting discussion, but in the real world, will we ever know
for sure? If my motor lasts 160K miles with K&N filters and Dave’s lasts
170K miles without, can we conclusively say the air filters made the
difference? Or the motor oil? Or the…whatever ? What about all the other
variables? How do we separate those out of the mix?

Now, show me two 4.2 engines, driven under the same conditions, one with and
one without K&N filters, where one lasts 160K miles and the other has
destroyed cylinder walls at 50K miles, then we have some to wrap our hands
around !

For someone…Gregory, let’s say …with multiple cars, driving
each only a few thousand miles each year, it would takes decades to see a
difference…if one can be detected at all.

I say “Use whatever air filter make you happy” because, in the end, that’ll
likely be the only way of determining what was the best choice for you :slight_smile:

Doug Dwyer
Longview, Washington USA
1987 Ser III XJ6
1988 XJS V12From: “Craig Talbot” talbotc@telus.net

. He’s an ex Jaguar mechanic and had his own race team for a while,
so did a lot of dyno testing with K&N’s installed versus the standard
air filter. He found that at 5500 RPM it made exactly 1 hp difference,
and in the lower rev ranges the standard air filter was actually superior.

On his race cars, he outfitted one car with a K&N, and another with the
standard air filter and measured the bores at the start of the season.
Near the end of the season he measured again, and found the car with the
K&N had significantly more bore wear than the standard car. In his words
the K&N only stopped “boulders” from coming into the engine. Personally,
I stick with the OEM filter.

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In reply to a message from 1985vdp sent Tue 24 Jan 2006:

Heya Dave,
The aussie guys on the list will know all about these
things,but if you ARE chasing the horsies,here’s something
to look at:
http://www.hiclone.com.au/

I was considering this with a K&N as well.I received an
E-mail from the guy with a whole lota facts and figures,but
I’m buggered if I know where it went.Must have deleted
it.Anyway,I tend to find more pressing things to blow my doe
on otherwise I would’ve got one mainly for the economy side
of things.
Cheers,
Gav Fisher
Newcastle,Australia
'82 Daim.Sov SIII–
The original message included these comments:

I decided to get a K & N filter not for their claim of
better horsepower, but since it is washable and reusable.
Any comments on this?
As an aside, I ran up the road with the front of the air
filter off, just a mile or two into town. The filter was
still in place. I just figured, the filter’s still in, I
need a new one, and its a short ride, shouldn’t be any
problem to the car. It was pretty funny, it sounded either
like a big muscle car, or an exhaust leak. Pretty funny for
an old Jag to sound like that.
Dave Williamson 85 XJ6 VDP ‘Black Beauty’


Gav Fisher
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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Wedgepig wrote:

In reply to a message from DAVE WILLIAMSON sent Wed 25 Jan 2006:

May I be allowed to throw some
gasoline on the fire?

Does additional(less constricted)
breathability (is that a word?) guarantee
increased performance (HP) in a
4.2L engine utilizing the Bosch/Lucas
L-jetronic fuel injection system.

I am curious if it does. Has anyone
dyno tested and established results
utilizing a K&N air filter -vs- a stock
air filter?

I am tempted to suggest there would be
negliable difference between the two,
however before I open yap and insert
foot, has anyone discussed/looked into
this before?

Heaps, Kirk - but to no agreement…:slight_smile:

The gains at tinkering with airflow are limited, and only valid towards
full throttle. The output of an engine is purely related to the amount
of air the engine is able to swallow - adding the required petrol for
max power is “easy”. And with less than full throttle you can always
increase air flow with more throttle…

The throttle is designed to control the air, and at lower throttle
settings the throttle itself is the main restriction. Easing air flow
upstream then has no effect, other than possibly making do with slightly
less throttle. Power output at this stage is the same as the engine is
still receiving the same amount of air - filter or no filter. The AFM is
measuring the same amount of air and is fuelling accordingly. There is
no more air going into the engine however smooth the air flow upstream -
as long as the throttle is the restricting. Not omitting the equally
important factor - getting rid of the exhaust

The manifold/valves/engine construction is a also “natural” air
restriction - even freebreathing upstream this will limit revs. And the
higher the revs the more air the engine can theoretically swallow and
the more power -or forcefeeding air with a compressor. At some stage
reaching the engines breaking point - and something gives, no engine is
indestructible…:slight_smile:

Gains can certainly be had throughout the engine rev range by improving
ignition timing which is very “primitive”. The distributor as we know it
is ancient, with very crude timing controls compared to the engine’s
requirements - not at all suitable for precise ignition timing. Adding
wear and tear doesn’t improve matters, either…

The J-Jetronic is not that precise either, after all the ECU has a
choice of only 128 different fuel settings - and adding its overall slow
reaction time. Also; the injection is not synchronised with valve
openings - it’s doing remarkably well in fact…

These are the areas where modern engines gains the advantage, adding
multiple gearboxes allowing engine to run at optimum economy. Ie,
getting more power out of every fuel drop. Adding lighter cars fuel
savings at cruising speed of some 20% is nt all that impressive. And
don’t be fooled by economy and max power quoted - using all its 400
horsepowers you can see the fuel gauge moving in a XJR…:slight_smile:

In short; within reason the filter’s impact on power is negligible - and
on economy none…

Frank
xj6 85 Sov Europe (UK/NZ)===================================================
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In reply to a message from Frank Andersen sent Wed 25 Jan 2006:

FWIW, some of the diesel gents have run K&Ns and periodically
checked oil analysis. Silicates (dirt) went up so they switched
back to paper filters; silcates went back down. Another
observation was a fine coating of oil on the intake plenum.
Granted, a 5.9L Cummins turbodiesel is a bigger air pump than the
4.2L XK but it may translate to some minor degree. I agree with
above - got bigger fish to fry than sweating what filter to use on
the XJ6.–
Cheers, Tom 1978 SII XJ6LFI 1996 Dodge/Cummins 2500
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In reply to a message from Frank Andersen sent Wed 25 Jan 2006:

I must again say, I am NOT, looking at engine performance
gains whatsoever, merely the fact that it is easier to
re-use a filter, since the off the shelf ones are becoming
more problematic to find. The price of the cellulose ones
are approaching the $20 range, the K&N cost me $31, and can
be used for a long time. the convenience of having a filter
that can be cleaned with their ‘magic cleaner’, probably an
alcohol solvent, that if I go with their filter, I will find
out what exactly they are using, and do it myself.

The filter is similar in design to the idea of oiling a
filter in your lawnmower, albeit it has significantly more
capture efficiency since it it made of a superior product
than the simple foam in my little push mower.

I tend to agree with the ‘we are picking fly s**t out of
pepper’ here comment after lingering on it a bit. If I can
trust the manufacturers claim of 97 to 99 % filtration, then
I am ok with that. In addition, at lower speeds, and
pressure drops for that matter, the efficiency should be
approaching the 99%. That to me is probably on par with a
cellulose filter.

Like my wandering thoughts of the previous post, the
particulate matter in my area in general is most likely
fairly big as far as micron size, therefore the filter IMO
is safe enough. Like someone else here said, he has used
them for years with no issues. Besides, at 156K miles on
the clock, I am sure my bores are pretty worn at this point.
Oil consumption still reasonable however.

My musing back and forth on this is being forced to and fro,
but I think I will go with my gut feeling on what I have
learned over the years in my schooling and experiences of
what I know about airflow and particulate loading. This is
of course trusting that K&N is being reasonably honest about
their claims.–
Dave Williamson 85 XJ6 VDP ‘Black Beauty’
Lansdale, PA, United States
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