Om K&N och eftermarknadsfilter

Pär H · Post by **Pär H** » Fri Jul 11, 2003 15:37

Hittade detta på ett 406 Coupé-forum:
==========================

"If the manufacturer could add horsepower to a car with a simple air
filter change without any ill effects, wouldn't they do so?"

K&N Filters
by Mike Perkins, Owner of Bavarian Machine Specialties
(originally published in Houston Chapter BMW Car Club of America
Newsletter, circa 1998)

"The promise of inexpensive horsepower gain is always an effective
method of promoting an aftermarket product. However, as with most
products claiming improvements beyond factory specifications, there
is commonly a compromise to go along with the gains. K&N filters are
no exception to this, and I do not recommend them to everyone.

There are basically two types of K&N filters. The first and most
common filter is the flat type. This filter fits directly on the
original air filter housing. The second type is a cone shaped filter
which requires removal of the stock air filter housing and requires a
special system to take its place.

Both types of K&N filters improve volumetric efficiency of the engine
because the filtering elements are less restrictive compared to the
original equipment. The cone type is more efficient due to its
greater available surface area. Both filters operate identically in
that less restrictive, less dense, cleanable pleated paper filter
removes larger debris and grit from the air. In addition, the paper
element of each filter is coated with a film of special oil that
enables the filter to trap minute particles without the need for
additional restrictive paper pleating. So far, this is all good stuff
and it works well. However, there are compromises that must be
considered.

As you can imagine, an oiled filter can clog up rather quickly. When
the filter becomes clogged, two problems occur: 1) the filter becomes
more restrictive than the stock unit; and 2) the filter untimately
traps less particles. The immediate concern is that filters must be
cleaned every 3,000 to 6,000 miles, depending on conditions. Routine
cleaning, to be effective, requires a pressure cleaning system
combined with a cleaning agent to clean the element, as well as
adequate drying time and re-oiling of the pleated paper element. (A
cleaning/oiling kit can be purchased separately).

In an independent study that provided comparison testing of a K&N
filter and a stock unit, the results showed unequal levels of engine
protection. Presupposing both units were cleaned or replaced
respectively on a regualr service interval, the K&N unit allowed more
microns of dirt/grit into the engine per mile. Over a long period of
time, this translates into worn rings and cylinder walls.

The final issue regarding the use of K&N filters concerns the cone
type. Typically the stock housing is removed to install this unit.
Our own testing of this type of setup, in fact, produced less
horsepower at the track than the stock unit. The stock system will
only allow air to flow into the filter from the front of the car,
usually from behind the grill. This means cool, fresh air. On the
other hand, the cone filter, left to dangle from the air flow meter
or air mass meter, receives hot engine compartment air, or worse, hot
radiator air. Engines simply make more power with cool air...

In conclusion, K&N filters can be a excellent and sometimes necessary
upgrade to be used in conjunction with other engine modifications or
race engines. This, of course, requires the strictest of maintenance
schedules. However, the benefits for a street car are questionable,
especially when an extremely effective original equipment air
filtering system already exists."

Johan Jatko · Post by **Johan Jatko** » Fri Jul 11, 2003 16:18

Intressant...

Claes B · Post by **Claes B** » Fri Jul 11, 2003 20:33

Hmm... det verkar som de flesta är mest ute efter ljudet i vilket fall som helst...men att t.om. K&N-filtren släpper igenom mer partiklar måste ju betyda att betydligt billigare filter släpper igenom ändå mer, eller?

Calle · Post by **Calle** » Sat Jul 12, 2003 11:50

www.itgairfilters.com

Kika på Product Philosophy.

Andreas Bystedt · Post by **Andreas Bystedt** » Sat Jul 12, 2003 17:02

Pipercross har väl skum i sina filter också. Borde ju vara samma teknik..

André V · Post by **André V** » Sat Jul 12, 2003 17:16

Pappfilter och inoljade skumfilter är säkert det bästa (filtreringsgrad kontra tryckfall) eftersom tex diverse japanska sporthojar brukar vara försedda med någon av dessa typer från fabrik.

Själv dumpade jag mitt K&N 57i till förmån för orig. luftburk igår. Även om jag kanske tappar 2 hästar (på sin höjd) jämfört med ett nytvättat K&N-filter känns det som om originalet funkar bättre totalt sett över hela registret. Framför allt är det inte så känsligt för "smutsighetsgraden", och jag slipper fullgasbrölandet som jag börjat bli lite trött på. :oops:

Läste en annan artikel på nätet (som jag inte hittar) ang. tryckfall i insugssystemet. De hade helt enkelt mätt på diverse punkter var det största tryckfallet skedde, och det var inte i själva filterelementet. De kom fram till att ett panelfilter var rätt poänglöst, och att de största restriktionerna låg i märkliga rördragningar och utformningen av bilens egen LMM. Men det allra viktigaste är i vilket fall att motorn får frisk, kall luft.

Calle · Post by **Calle** » Sat Jul 12, 2003 17:50

Bystedt wrote:Pipercross har väl skum i sina filter också. Borde ju vara samma teknik..

Ja det har dom.

Fnatte · Post by **Fnatte** » Tue Jul 15, 2003 15:17

På min bil, 206a med 1,6 liters motorn, så funkar bilen "bättre" med öppet filter. Det jag menar är att motorns möjlighet till segdragning är mycket bättre än när jag har originalfilter på.
Den orkar lite mer helt enkelt, men sen att den inte funkar så bra under acceleration är en annan sak. Det är nästan att den bara låter och inte accar...