Frequently Asked Questions
- How much of
an increase in miles per gallon should I see from
using a K&N air filter or intake kit (Fuel
Injection Performance Kit – FIPK, Typhoon, or
increase in horsepower should I see from a K&N
increase in horsepower should I see from a K&N
intake kit (Fuel Injection Performance Kit – FIPK,
Typhoon, or Aircharger)?
- Are K&N
filters emissions legal?
- Are K&N
Fuel Injection Performance Kits – FIPK’s street
legal and will I have a problem passing state vehicle
inspections due to the altering of my air box?
- Will a
K&N filter cause my vehicle’s mass air sensor to
- Can an
engine get too much airflow?
- Should I
install the largest K&N filter that will fit in my
- Will I need
to make adjustments to my vehicle after I install a
K&N filter or intake kit?
- What is
the micron rating and filtering efficiency of the
- How much
does an air filter cost? Call Toll Free
- How much
does an intake kit cost?
a K&N filter be made at the factory for any
important is the sealing grease?
the use of a K&N filter void my factory warranty?
the filters come pre-oiled or must they be oiled
the cotton gauze shrink from engine heat?
it OK to rotate round filter to get more longevity?
do I know when to clean the filter?
I use anything other than K&N cleaner and oil?
I use compressed air to dry the filter faster?
I brush the wire screen with a toothbrush to get all
the “crud” off?
do K&N filters differ from other brands of
much of an increase in miles per gallon should I see from
using a K&N air filter or intake kit (Fuel Injection
Performance Kit – FIPK, Typhoon, or Aircharger)?
Results will vary depending on your vehicle, driving
habits, load on the engine (towing for example), existing
air system restriction, and other factors. Many
K&N users report an increase in miles per gallon.
K&N air filters and intake kits provide less
restriction on your engine’s air intake than typical
original equipment manufacturer (OEM) filters and air box
systems. Less restriction provides for a more efficient
(increased power and/or higher MPG) engine. Our tests
primarily measure power gain. Our testing is
performed using employee and customer vehicles. We usually
have the cars for a short period of time that will only
allow for fit checks and dyno (power curve) testing. If
you take advantage of added power by driving harder, you
will not see much of a gain, if any, in MPG. Also if you
add a K&N filter and the primary source of air
restriction in the OEM system is the air box, you won’t
see much of a difference in power or MPG unless you add a
K&N intake kit to reduce the restriction.
2. What increase in horsepower should I see
from a K&N replacement filter?
We perform dyno (power curve) testing on our products. Our
replacement filters typically provide a 2 to 4 percent
horsepower increase. Your results will vary depending on
your vehicle, driving habits, load on the engine (towing
for example), existing air system restriction, and other
3. What increase in horsepower should I see
from a K&N intake kit (Fuel Injection Performance Kit
– FIPK, Typhoon, or Aircharger)?
K&N intake kits (Fuel Injection Performance Kit –
FIPK, Typhoon, or Aircharger) typically provide a 5 to 8 %
increase in power. For instance, our tests on a Jeep Grand
Cherokee had repeated gains of 26.3 horsepower. We also
have dyno test results showing increases through the
towing range of no less than 23 ft. lbs. Your results will
vary depending on your vehicle, driving habits, load on
the engine (towing for example), existing air system
restriction, and other factors.
4. Are K&N filters emissions legal?
All K&N direct replacement filters are emission legal.
They do not require any modifications and go directly in
the stock air filter housing. Universal clamp-on filters
may not be legal in states where under the hood
modifications are not allowed. Since they can be used on
just about anything, it would be impossible to have all
the different filters tested for all possible
applications. Check your local laws if you are unsure.
5. Are K&N Fuel Injection Performance Kits
– FIPK’s street legal and will I have a problem
passing state vehicle inspections due to the altering of
my air box?
K&N FIPK’s are legal in all 50 states. Each FIPK and
Typhoon intake kit has been submitted and approved by the
California Air Resources Board (CARB). Since California
has the toughest emission laws in the country, they have
been accepted as legal by other states. Each of these kits
comes with a high temperature sticker with the CARB
approved “EO” number. This sticker differentiates
approved devices from non-approved devices. As long as you
have the approved sticker you shouldn’t have any
problems with vehicle inspections. Our Aircharger intake
kits may not be legal in states where under the hood
modifications are not allowed. Check your local laws if
you are unsure.
6. Will a K&N filter cause my vehicle’s
mass air sensor to fail?
No. A properly oiled K&N filter will not contaminate a
mass air sensor. However, if you over oil your filter it
is possible for oil to drip off the filter and contaminate
the sensor. In the last few years certain vehicles have
had design problems with the mass air sensors. Some local
dealers have attempted to blame the problem on a K&N
filter, however, of all the sensors we have sent off to be
tested we have yet to find one that failed due to oil
contamination. The defect in all cases was within the mass
air sensor unit. If oil were to contaminate the sensor’s
“hot wire”, the wire itself could be cleaned, however
if there were a problem with internal circuitry the sensor
would have to be replaced.
7. Can an engine get too much airflow?
No, an engine can only take in a fixed volume of air
depending on the engine’s size. The more restriction
that an air intake system (filter, air box, and tubing)
causes, the greater the potential is for power and mileage
8. Should I install the largest K&N filter
that will fit in my race vehicle?
If an existing K&N filter is large enough to provide
negligible restriction, a larger than required filter will
not affect the amount of air an engine can take in,
however, it will lengthen the filter’s service interval.
A longer service interval, however, can be an important
factor when racing in dusty, dirty environments.
9. Will I need to make adjustments to my
vehicle after I install a K&N filter or intake kit?
On fuel injected vehicles the original equipment
manufacturer (OEM) computer and emission control system
will adjust for the increase in air. The OEM computer will
adjust immediately if it is reset. Removing the battery
cable from the battery for 15 minutes or more should reset
it. On some carbureted models you may have to richen the
mixture when switching from a paper filter to a K&N
air filter or intake kit.
10. What is the micron rating and filtering
efficiency of the K&N filter?
K&N air filter designs are tested both in house and by
independent testing laboratories for air flow, filtering
efficiency and dust retention. The Society of Automotive
Engineers (SAE) establishes testing standards for
automotive air filters. Independent testing of panel and
round K&N air filters has confirmed an overall
efficiency rating of over 99% when tested using the SAE
J726 air filter test code. The test results provide
scientific details including particle size, size
distribution, testing methodology and results. The overall
results establish the superiority of our filters against
the “competition”. The OEM minimum specification is
96% with ISO (International Organization for
Standardization) test dust which consists of a majority of
0 to 5 micron particles but some up to 20 microns in size.
Test results showed that a paper filter has a 99.29%
cumulative efficiency and a 96.47% initial pass. A K&N
filter, with far less restriction than paper, has a 99.05%
cumulative efficiency and a 97.11% initial pass.
11. How much does a filter cost? Call
Toll Free 1-888-2012066
It depends upon the application. They can range anywhere
from $35.00 up to $80.00. Size, shape, and materials used
to manufacture the filter affect the price.
12. How much does an intake kit cost?
It depends upon the application. The average price range
is from $150.00 to $400.00. The main factor that affects
the price is the cost of the materials to make the kit.
The more parts changed, the greater the price.
13. Can a K&N filter be made at the
factory for any application?
Yes, we can make just about anything, but the cost can be
prohibitive on panel types. Generally, we only change the
height of existing round filters. This includes
cylindrical, conical and oval filters clamp-on or not.
14. How important is the sealing grease?
It is rather important. It helps to maintain a seal on an
uneven surface as well as it helps to keep the air box
lids from catching and tearing the seal. If sealing grease
is unavailable, a white lithium or a synthetic grease will
work just fine. Do not use petroleum-based products, as
they will damage the seal.
15. Will the use of a K&N filter void my
It is against the law for a manufacturer to require the
use of a specific brand of air filter unless they are
providing it free of charge under the terms of the
warranty. This is stated in the Magnuson-Moss Warranty Act
and the general principles of the Federal Trade
Commission. The customer may use any brand of filter they
like if the dealership is not providing filters free of
charge as part of the warranty. This does not hold true
for fleets or government agencies.
16. Do the filters come pre-oiled or must
they be oiled before using?
K&N filters come pre-oiled and ready to use. The
filter media is made from layers of white cotton gauze.
The oil has a red dye added to show how much is being
applied. If the filter looks pinkish-red, it is oiled. It
is important that K&N air filters are never used
unoiled. This would greatly degrade their filtering
17. Can the cotton gauze shrink from engine
No. You will not have a problem with the material
shrinking as long as the proper cleaning solutions and oil
are used. K&N filters come with a limited 10-year
18. Is it OK to rotate round filter to get
This is perfectly OK and even recommended. Most vehicles
have a “favorite” spot to draw air in from and
rotating the filter will keep it clean longer.
19. How do I know when to clean the filter?
The general rule of thumb is that the filter needs to be
cleaned when the dirt build up gets as thick as the wire
mesh. The usual interval is 30,000 - 50,000 miles
depending on driving conditions. We recommend that you
check your filter about once a year in normal usage.
20. Can I use anything other than K&N
cleaner and oil?
We recommend that you only use K&N oil and cleaner.
K&N air filter oil is a compound of mineral oil
blended with special polymers to form a very efficient
tack barrier. We have performed tests on numerous oil
combinations and our blend has the required properties for
maximum flow and filtration. Petroleum products such as
transmission fluid and motor oil will soften and destroy
the rubber sealing edges. Our cleaner is a non-detergent
degreaser. Solvents and gasoline will harden the rubber
seals causing the filter to distort (shrink). A mild
detergent can be used in a pinch, but care should be taken
to fully rinse it out. Rinsing detergent out of a filter
is similar to getting soap out of a sponge; it’s not
that easy to do. Always make sure the filter is completely
dry before re-oiling.
21. Can I use compressed air to dry the
No, this can blow the filter material right out of the
wire mesh and ruin the filter. Pick a nice day to clean
the filter and let it dry naturally.
22. Should I brush the wire screen with a
toothbrush to get all the “crud” off?
No, this could tear up the cotton gauze. A soft bristle
paintbrush is a better idea and is recommended on the
23. How do K&N filters differ from other
brands of filters?
Most of our competitors use synthetic fiber, foam, or
paper as opposed to our 4-ply cotton gauze material. These
materials do not have the very small fibers that natural
cotton does. Only our reusable filters provide the high
airflow capability while also providing a high filtering