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Paper vs K&N
By comparison, paper filters are made from compressed fibers. The
spaces between these fibers provide microscopic holes the air must pass
through. One by one, these holes become plugged with dirt and dust
particles. Once a hole becomes plugged, the air must find an alternate
route through the medium. As the filter collects more dirt, its resistance
to air flow increases because there are fewer and fewer holes left open and
as restriction goes up, horsepower and fuel economy go down.
But to meet minimum filtration standards, the paper must be thick and/or
the fibers must be tightly compressed and dense. Therefore paper elements
that provide adequate filtration are restrictive to air flow by design. Any
paper element that could flow as much air as an equivalent K&N would not
provide safe filtration. Additionally, as a paper filter becomes more and
more clogged, the pressure inside the filter drops while the atmospheric
air pressure (approximately 14.6 psig at sea level) outside the filter
remains the same. It's like using your lungs to draw the air out of a
plastic milk bottle. When the pressure differential becomes too great, the
bottle will collapse. The same thing could happen to your paper filter,
although it is unlikely. But what will happen could be just as severe. An
excessively high pressure differential created by a restricted filter can
literally pull dirt particles through the paper medium. In other words, the
performance of a paper filter, i.e. air flow through the filter and its
ability to protect your engine, DECREASES near the end of its service
interval.
| Disposable Paper Air Filter |
|---|
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- Pleated wood pulp bonded together.
- As dirt builds, passages are plugged and filter must be replaced in approximately 10,000 miles.
- Irregular passages filter out dirt on a go/no go basis.
- As fibers swell from moisture or oil blow-by vacuum pressure increases and airflow decreases.
- Turbulent filtered air.
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| Typical Foam Air Filter |
|---|
 |
- Open cell foam usually saturated with oil.
- Dirt builds on outside and blocks the openings.
- Higher vacuum pressures distort the cells drawing dirt deeper into the filter.
- Airflow is reduced as cells become blocked.
- Turbulent filtered air.
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The K&N air filter is somewhat more complex. The unique design
features an oiled cotton fabric which holds airborne dirt particles. These
dirt particles cling to the outside of the filter and actually become part
of the filtering media. The cotton fabric is sandwiched between pleated
aluminum screen. Pleating increases surface area which in turn promotes air
flow and prolongs service intervals. Pleating exposes five times the
surface area compared to a flat element like foam.
The dirt particles collected on the surface of a K&N element have
very little effect on air flow because there are no small holes to clog.
Particles are stopped by crisscrossed cotton fibers and held in suspension
by the oil. As the filter begins to collect debris, an additional form of
filter action begins to take place because air must first pass through the
dirt particles trapped on the surface. That means the filtration efficiency
of a K&N element actually increase as the filter collects dirt. Tests have
shown a K&N E-1500 filter will flow 60 percent of its maximum flow capacity
after 50,000 miles of street use. And, considering a new K&N flows half
again as much air as a comparable paper element, that same filter will
provide all of the air the engine needs even after 50,000 miles.
Conversely, dirt trapped by a paper element will impregnate the
fibers which will impede air flow at a proportional rate. In other words,
performance decreases dramatically as a paper element gets dirty. At the
service interval, say 14,000 miles, air flow through a paper element can
decrease as much as 70 percent.
The efficiency of K&N's oiled cotton gauze medium has been proven time and
time again. The condition of the filter can be monitored with a vacuum
gauge. The vacuum reading increases as the filter nears its service
interval. A high vacuum reading means the filter is dirty and needs to be
serviced. Some trucks have logged over 100,000 miles with no loss in air
flow as reported by the service technicians. Again this is due in part
because a clean K&N filter will flow half again as much air as a comparable
paper element.
A K&N will provide superior filtration without sacrificing air flow
for a longer period of time - that's performance with value.
Stock Replacement Filters
For the service-minded consumer, utilizing the stock air filtration
system is easiest so we manufacture exact replacement air filter elements
to fit in place of the factory filter. Dimensions are held to minimum
acceptable tolerances to insure a perfect fit inside the stock air box.
Molded rubber sealing surfaces, edges and/or end caps combined with our
unique pleated cotton gauze medium creates a filter that is so durable we
warrant it for ONE MILLION MILES or 10 years. And, K&N original equipment
replacement filters are emissions legal in all 50 states.
Street engines are exposed to the same risks as racing engines but
for a longer period of time. In this application, a permanent, high
performance air filtration system must be durable enough to last the
lifetime of the vehicle as it travels through any and all driving
conditions.
Getting back to air flow for a moment, we have discussed stock air
filtration systems and why they compromise air flow. We have also explained
how K&N's unique design is less restrictive compared to a paper element.
Installing a K&N Filtercharger in place of a original equipment or
aftermarket paper filter removes the restriction which then allows the
engine to inhale all of the air it can physically use. Increasing the
amount of air available to the engine promotes performance since oxygen in
the air is a necessary ingredient for combustion. If you have a computer
controlled fuel injected car, the computer will automatically add the right
amount of fuel to compensate for the additional air. If your engine is
carbureted, more often than not, no adjustment will be necessary. However,
for competitive motorsport, it may be necessary to re-calibrate the
carburetor to achieve optimum performance.
The amount of performance gain varies from vehicle to vehicle. A
small displacement four cylinder engine may only realize a two or three
horsepower gain while it isn't uncommon for a 350 cubic inch V-8 to gain 10
horsepower or more. The greater the restriction created by the stock paper
element, the greater the performance gain when you switch to a K&N filter.
Washable and Reusable
A second and equally important attribute of a K&N filter is its
ability to be cleaned. Simply wash, dry and re-oil the element at regularly
scheduled intervals as illustrated in the cleaning instructions included
with your Filtercharger (and in the back of this catalog), and it will
continue providing your engine with clean air for the lifetime of your car.
A K&N Filtercharger can be washed and cleaned up to 25 times. We recommend
inspecting the filter every 30,000 miles or 12 months. If cleaning isn't
warranted, re-oil the element to insure optimum filtration efficiency is
maintained. Apply a small amount of oil to the clean side of the element.
Beyond the Stock Air Filter and Air Box
Addressing the next area of restriction, K&N engineers looked at
the vehicle's air box (the container that houses the air filter) and any
hoses or duct work connecting it to the engine. Because the air must first
travel through this system before it reaches the carburetor or throttle
body, the overall size and shape of the system has a profound effect on air
flow. Because air flows like water, it does not like to turn corners nor
does it react favorably when confronted by an obstruction such as a sharp
bend in a hose or a baffle. In most cases, the air box and/or the hoses and
duct work used to create the air filtration system is just as restrictive
as the original paper filter element. In some extreme cases, the air box
and/or the air delivery system is the greatest source of restriction. The
inlet to the air box is a good example. In many instances this opening is
one half the cross sectional area of the throttle body or carburetor
opening. It would be like trying to run a marathon while breathing through
a soda straw.
An original-equipment cylindrical air cleaner box covering a throttle body
or carburetor is another example. Most often, these round air cleaner
housings are sealed to the outside air. The engine must then breathe
through a snorkel attached to the perimeter of the housing. At times the
snorkel is fed through a network of hoses and scoops.
To directly address the problem, we introduced a line of
Filtercharger Injection Performance Kits (better know by the acronym, FIPK)
that eliminates both the air box and the restriction. Our FIPKs vary in
design because they are application specific meaning each kit is engineered
to fit a particular make, model and year of vehicle.
FIPKs utilizes a 360-degree filter design which provides increased
surface area to promote air flow. Port injected engines are outfitted with
a conical shaped filter while centralized fuel injection systems are sized
with an open element cleaner which again, makes available all of the air
the engine can physically use.
Off-Road and Racing
Off-Road
An air filter element becomes an insurance policy when used in
off-road applications. Competitors will sacrifice a high-tech engine for a
chance to win a race - but to win, they must finish. If the engine ingests
too much dirt and debris, it may die an ugly death before the vehicle can
cross the finish line.
You might think this would be the perfect application for an
inexpensive, throw-away paper filter. But remember, in competition a little
extra horsepower can mean the difference between coming in first or
finishing second. The air filter now becomes an important part of the
performance package. That's why most off-road competitors choose K&N
filters. The reason? K&N filters offer maximum air flow without sacrificing
filtration quality - even when they become packed with dirt. The fact is,
dirt buildup on the boundary layer actually enhances the filtration process
because it adds to the filtering medium.
Remember, on average a K&N filter will flow 50 percent more air
compared to an equivalent paper filter. That means if all other conditions
remain the same, a K&N filter will flow half again as much air as a paper
filter at any point during the race.
Let's consider some hard numbers.
If a paper filter flows 700 cfm of air at a measurable degree of
restriction, an exact replacement K&N filter will flow 1050 cfm at that
same level of restriction. Keep in mind, this is an example using average
flow numbers. Exact variables differ from filter to filter depending on the
size, shape and configuration each filter being tested.
If both filters are run in the same off-road race, lets assume each
collects exactly the same amount of dirt and that by the halfway point in a
24 hour race, the efficiency of both filters has dropped 50 percent. The
paper filter is now flowing 350 cfm of air and the K&N is allowing 525 cfm
of air to pass through. As impressive as these figures are, our example is
seriously flawed because flow bench tests have proven a K&N filter will
provide closer to 100 percent of the required air flow long after the
efficiency of a paper filter has dropped to 50 percent. In other words, due
to its characteristics, the efficiency of a K&N replacement filter drops at
a slower rate when compared to a paper element, i.e. a K&N filter will last
longer under the same conditions.
Using our hypothetical 24-hour off-road race to further the point,
a properly sized K&N filter will see the racer through to the end with cfm
to spare. The equivalent paper filter, on the other hand, will need to be
replaced with a fresh element to ensure the engine has an adequate supply
of air to complete the course.
Racing
One might consider a paved road course or oval track as a clean air
zone. After all, how much dirt and debris could be hovering above an
asphalt track?
Subscribing to that theory, a road racer may elect to forgo an air
filter in favor of large volumes of unrestricted air. However, testing the
theory using an air filter enclosed in a vented housing should dispel the
myth. The filter and housing will trap particles of loose trash kicked up
by other race cars during the heat of battle. Dirt, small stones and pieces
of shredded rubber expelled from soft compound racing tires can be found
inside the housing after even a short race. Once a driver, car owner or
engine builder realizes just how much trash is thrown around during a
normal race, few would expose their expensive engines to unfiltered air in
future events.
Whenever possible, performance enthusiasts should install a K&N 360 degree
open-element filter. A correctly sized conical or round filter will deliver
100 percent air flow with no measurable restriction. And, as we have
learned, providing the engine with all of the air it needs promotes optimum
performance. In a high speed application, a K&N filter will straighten the
air which counteracts turbulence.
Straight cut velocity stacks, for example, pose a unique problem. Exposed
to the outside air, velocity stacks experience a phenomena that actually
hinders performance at high speed. We are referring to stacks and air horns
that protrude through the hood and extend into the air stream so the
direction of the air rushing over the car is at a perpendicular angle to
the length of the tube.
Air moving rapidly over these stacks create turbulence inside the
opening. At high speed, the rushing air tends to create a partial vacuum
inside the tube. The condition is counterproductive to air flow. The
phenomena also effects open carburetors. The higher the ground speed, the
greater the problem. Vacuum created by the engine is trying to coax air
into the cylinders and the high speed air flowing over the open end of the
stack is causing resistance.
Reversion creates other problems. In an automotive application,
reversion refers to reversed air flow, or in simpler terms, it's when air
in the intake runner reverses direction for a split second. The condition
is caused when a burst of pressure escapes into the intake runner from the
cylinder during valve overlap.
Studies have shown reversion creates resonance shock waves inside the tubes
which exit the open end of the tube at various rates depending on engine
speed. It has also been proven that these shock waves interfere with each
other when the stacks are in close proximity.
Installing a free-flowing air filter on top of each stack or over the
carburetor air horn eliminates these conditions.
How? The solution is simply explained.
The filter creates a plenum over the opening. Air entering the filter is
slowed, smoothed and straightened. The filter then becomes an endless
source of calm, clean air. Shock waves dissipate within the confines of the
plenum without interfering with the shock waves emitted from an adjacent
stack.
Why K&N Is Good For The Environment
As a point of comparison, lets say the average automobile, truck or
motorcycle has a useful life of 150,000 miles. Admitting most motorcycles
and some cars never reach 150,000 miles and most commercial trucks travel
well over that amount, our hypothetical lifetime mileage figure could be
considered a conservative average. Consider there were 197,000,000 vehicles
registered in the United States in 1994. If each owner replaces the
vehicle's paper air filter every 12,000 miles or one year, they will throw
away 197 million filters every 12 months. That's 197,000,000 used filters
finding their way into our landfills every year. Multiply that times 12.5 -
the number of filters that same owner will replace over the lifetime of the
vehicle given the same service interval - and you realize we are dumping
two billion four hundred sixty two million five hundred thousand (that's
2,462,500,000) used air filters in our landfills every 13 years!
If each and every one of those owners replaced their original paper
air filters with a reusable K&N filter element, 2,265,500,000 fewer filters
would be purchased, used and thrown away over the lifetime of those same
197,000,000 vehicles. How's that for environmental awareness?
Filter Selection
If maximum horsepower is the objective, the size and shape of the
air filter element is paramount.
Let's first consider shape. When a fitting a conventional round
filter on top of the engine, such as a carburetor, central fuel injection
or throttle body fuel injection, we have found a large diameter, short
filter will flow more air than a small diameter, tall filter. For example,
a 10-inch diameter filter 2-inches tall will flow more air than a 5-inch
diameter filter that is 4-inches tall. Where space permits, the height of
the filter should be between 1/5 and 1/4 of its diameter.
The shape of the filter is less important if the application calls
for a remote mounted filter, which includes many late model fuel injected
models. Typically these vehicles will use a flat panel filter or a conical
or cylindrical shaped filter with a rubber mounting flange designed to be
mounted on the end of the inlet hose.
That brings us to size.
Pleated K&N filter material will flow 6.03 cfm of air per square
inch. By comparison, a single square inch of the highest flowing paper will
allow 4.95 cfm of air to pass and the freest flowing foam will flow 4.38
cfm. Use the formula below to compute the minimum size filter required for
your particular application. The usable portion of the filter is called the
EFFECTIVE FILTERING AREA which is determined by multiplying the diameter of
the filter times Pi (3.1416) times the height of the air filter in inches,
then subtracting .75-inch. We subtract .75-inch to compensate for the
rubber seals on each end of the element and the filter material near them
since very little air flows through this area.
 |
A = effective filtering area
CID = cubic inch displacement
RPM = revolutions per minute at maximum power
|
| Example: A 350 CID Chevy engine with a horsepower peak at 5,500 rpm. |
 |
If you are sizing a panel filter, multiply the width of the filter
area (not the rubber seal) times its length. If you are sizing a round
filter, use the following formula to determine the height of the filter.
 |
A = effective filtering area
H = height
D = outside diameter of the filter
3.14 = pi
.75 = the rubber end caps
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| Example: |
 |
Referencing the K&N Flow Comparison Chart shows the
proper filter for this application would be an E-1500 which is 3.5 inches
tall. Keep in mind, this is the minimum size requirement. To extend the
service interval and to provide an even greater volume of air to the
engine, install the largest filter that will fit in the space allotted. If
the space above the engine is restrictive, perhaps a remote filter
arrangement could be used to gain space.
|
FLOW COMPARISON CHART |
 |
| Foam |
Amsoil LT-31;
Unifilter 04-0031 |
376 CFM |
| K&N (used)
| (42,000 miles)
K&N E-1500 |
463CFM |
| Paper |
AC A348C; Fram CA326;
Hastings AC-145; K-Mart KA-12;
Motorcraft FA-71R |
508 CFM |
K&N
Filtercharger
® |
K&N E-1500 |
887 CFM |
TEST NOTE #1: All air filter elements were flow tested at .3" H20
(water) restriction and then converted to 11/2" H20 restriction by using the square law formula.
TEST NOTE #2: All elements tested were of equal size (12" od x 31/2" H) and were specified by
their respective manufacturer for the same application.
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Off-road conditions require added filter area. A filter should be
sized 1-1/2 to 2 times larger than normal for any conditions that could be
considered severe. In this case, the E-1500 used in our example should be
replaced by an E-1120 or an E-1150. For long distance off-road events, two
double-size remote mounted filters would be best.
Some important tips about K&N Filterchargers
Service Interval
A K&N Filtercharger is a high-performance air filter, both in terms
of air flow and filtration. However, the service interval can vary widely
depending on the severity of the driving conditions. The service interval
can be from 100 miles, such as a desert-racing motorcycle, to 100,000 miles
exemplified by a commercial semi truck. The proper way to determine when an
air filter needs service is with an air restriction gauge. Such a device is
commonly used on heavy duty trucks and construction equipment. A
restriction gauge, or vacuum gauge, measures the pressure differential
inside and outside the filter and relays the information in the form of a
numeric value or a red/green, pass/fail indicator. As the filter collects
more and more dirt, the restriction value increases. At a predetermined
point or rate of restriction, the filter is serviced. The maximum allowable
of restriction for a K&N Filtercharger is 15-inches of vacuum (water). If
the restriction is allowed to go higher, the filter media might become so
restricted that the element could distort allowing dirty air to bypass the
filter and enter the engine. Conversely, cleaning a filter too often
shorten its serviceable life expectancy.
Installing a K&N electronic restriction gauge will optimize service
intervals and take the guess work out of your maintenance schedule. Instead
of arbitrarily cleaning your filter at a predetermined distance or time
interval, an LED light scale will report your filter's condition at a
glance.
Service Life
A K&N Filtercharger can be washed up to 25 times before it is
considered no longer serviceable. Even though the filter may not show
outward signs of deterioration, it should be replaced after 25 washings.
Excessive washings will deplete the tiny cotton hairs that crisscross the
openings. The resulting damage will allow tiny dust particles to pass
through.
Limited Warranty
K&N's warranty covers defects in materials and workmanship. Any K&N
product deemed defective will be replaced free of charge. However, K&N is
not responsible for damage or abuse. Nor can we be held responsible for
inconsequential damage resulting from a damaged filter or a defective or
damaged filtration system.
Over-oiling
When servicing a K&N filter, take care not to over-oil the element.
Besides impeding air flow, excess oil can migrate into the intake system
where it can coat electronic sensors, which may hinder their operation.
Never saturate the filter. If oil drips from the filter, wash it and start
over. Use only K&N oil. For example, an E-1500 filter has 92.4-inches of
surface area requiring 1.707 fluid ounces of oil. Follow oiling
instructions included with your filter or refer to the instructions listed
in the back of this catalog.
Fit and Finish
When installing a K&N filter, check all gaskets, clamps and seams
for damage and/or deterioration. Check the filter's sealing surface. Do not
install a filter if the seal shows signs of damage or deterioration. Check
for cracks in the air box, particularly at the seams and around the
corners. Such defects could cause air leakage around the filter. Also,
check to insure the filter is sealing properly in the air box. A plastic
air box can warp from age or continuous heat cycling. Apply a thin layer of
filter grease on both sides of the seal each time the filter is installed.
An impression in the grease will indicate a positive seal. Check any lines
or hoses connected to the air box or adjoining hoses leading to the engine.
Engine oil in the air box, resulting from excessive blow-by, will cause the
filter to shrink and possibly lose its seal. Clean any dust or debris out
of the air box with a damp cloth, making sure nothing enters the air inlet
while the filter is out. Never start the engine without the filter in
place. Use only K&N Air Filter Cleaner to clean your filter. Harsh
household cleaners can damage the cotton material and/or the rubber seal.
Check the outside of the medium for broken wires, rips or tears. Do not use
an element that shows signs of damage or wear. Use K&N Air Filter Sealing
Grease on the sealing surface that contacts the air box. Do not use sealing
grease on clamp-on type filters.
If a filter is especially difficult to install, it will come with an
instruction sheet explaining the correct installation procedure. Keep the
instruction sheet with the vehicle for reference anytime the filter is
removed. It is very important the filter be installed correctly. The filter
can be positioned in the base or the lid, whichever is more convenient and
makes the installation easier. Do not use excessive force to install a
filter.
Vehicle Warranty
Contrary to what you may have heard or read, a K&N Filtercharger
will not void your vehicle warranty. The Magnuson-Moss Warranty Act passed
in 1982 makes it illegal for a manufacturer to void a new vehicle warranty
if the consumer uses non-OEM filters unless that manufacturer provides
filters free of charge. If the manufacturer does not provide air filters
free of charge, they cannot void the vehicle's warranty simply because you
have installed an aftermarket air filter.
Summary
We offer over 1000 stock replacement applications, hundreds of
universal clamp-on filters and dozens of Filtercharger Injection
Performance Kits. Our goal is to provide the highest quality component at a
competitive price. A K&N Filtercharger will be the last filter you will
ever buy for your car, truck, motorhome, motorcycle, ATV, boat or jet ski -
Guaranteed.
Warranties on New Vehicles
THE MYTH:
A manufacturer's new-vehicle warranty is automatically voided once an
aftermarket part (non-original equipment) is installed.
THE TRUTH:
Rarely does the use of aftermarket parts violate a new-vehicle warranty.
THE RULES:
Federal law, (the Clean Air Act), requires two emissions warranties: a
"defect" warranty and a "performance" warranty.
"Defect" warranties require the vehicle manufacturer to produce a vehicle
which, at time of sale, is free of defects that prevent it from meeting
required emission levels for it's useful life, as defined in the law.
"Performance" warranties require that vehicle manufacturer to make repairs
- at no cost to the owner - should the vehicle fail to meet certain
levels of emissions performance during the warranty period. This period
ranges from 2 years or 24,000 miles to 5 years or 50,000 miles for most
parts, to 8 years or 80,000 miles for certain emission-controlled parts
(specifically, the catalytic converter, the electronics emission-control
unit and the on-board diagnostic device) on most 1995 and later vehicles
(check owner's manual for specifics on your vehicle).
Consumers are protected under a parts self-certification program
administered by the Environmental Protection Agency (EPA).
If a parts maker self-certifies it's parts under this program, the vehicle
manufacturer cannot void the emissions warranty even if the certified part
fails and/or is directly responsible for the emissions warranty claim. In
this situation, the vehicle manufacturer must arrange a settlement with the
parts manufacturer, but the new vehicle warranty is not voided under the
law.
If a parts maker chooses not to self-certify it's parts, the only case
where a vehicle manufacturer can void the emissions warranty is if a
non-certified aftermarket part is proven to be responsible for an emissions
claim.
All K&N direct replacement air filters AND all K&N F.I.P.K. kits - -
Filtercharger Injection Performance Kits - - are emission control exempt
and they will not void your new car warranty.
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