K&N maintains testing facilities in the USA, the UK and the Netherlands. These facilities incorporate both airflow and horsepower/torque testing capabilities. Their horsepower/torque testing is performed on wheel-based dynamometers, which measure actual brake horsepower and torque at the wheel(s) receiving power from the drive train. This is different and we believe more realistic than horsepower/torque testing done at the flywheel of an engine because the power lost between the engine and the wheels does not contribute to the power needed to put a vehicle in motion. Their standard horsepower/torque testing is designed to measure relative power differences on a vehicle with and without K&N products installed. Their horsepower and torque numbers use SAE (Society of Automotive Engineers) correction factors. They attempt to hold all other variables constant to generate a reliable measurement of changes in horsepower and torque on a vehicle before and after a K&N product is installed.
To test the Dust filtration efficiency for a particular air filter, they use both an independent lab and their own dirt retention laboratory to conduct such tests in accordance with the ISO 5011 testing procedure.
Power Gain Charts
Because of some of the unbelievable claims of power gains made by other manufacturers of air filters and intake systems, they feel it is important that their performance claims are realistic and that they are clearly explained. The vehicles their R&D department uses for testing are loaned to us by consumers residing near their test facilities.
Some of intake kits have power gain charts, which show actual Dyno run plots. These plots show the median run of a specific vehicle, which had three runs with the original stock intake system and three runs with the K&N intake kit installed. The year, make, model, and engine type of the vehicle tested is shown on each chart. The ambient temperature and atmospheric pressure at the time of the run is printed on the chart along with the correction factor. The correction factor is used by the Dynometer to calculate the horsepower and torque relative to standard conditions. This correction factor helps to ensure that their power gain measurements are accurate and that the gains shown are not affected by changes in environmental conditions. They believe these power gain results are representative of the power similar vehicles should realize. Due to the uniqueness of each vehicle, there are occasions when a vehicle will experience a much larger or much smaller power gain than other identical model vehicles. While some of these power gains are incredible, they will not use a Dyno run that depicts an unrealistic increase in power.
Advertising Claims
Mechanical testing performed at one of their testing facilities supports all horsepower and torque claims advertised by K&N. Horsepower and torque claims are based on testing of an actual vehicle on a dynamometer before and after a K&N product has been installed. Airflow claims are based on tests performed in accordance with their own testing protocol in a dust-free environment on laboratory equipment. Filtration efficiency claims are based on tests performed in accordance with testing procedure ISO 5011. They believe these tests form a reliable basis for performance claims measuring relative differences in the results being compared. These claims are the result of specific tests performed on a given date. Your results will vary based upon such things as atmospheric and weather conditions, vehicle make, model, equipment, or condition, and the K&N part number in use. Their products are designed to provide increased performance and they are confident you will enjoy your K&N experience.
ENGINEERING AIRFLOW TESTING PROTOCOL
K&N Engineering performs all airflow testing on a SuperFlow Corporation SF-1020 flow bench. The SF-1020 is a computerized flow bench capable of measuring airflow rates up to 1020 cubic feet per minute (cfm) at test pressures of up to 65 inches of water.
K&N has developed the following procedures for measuring airflow and pressure differential (restriction) of the various size and shaped filter elements that they manufacture. These procedures must be followed to insure a consistent comparison of air flows between filters that are of differing material or manufacture.
Daily Calibration & Leak Check
The calibration check is a three step procedure to verify that the measurement of the flow bench is accurate and will be performed daily before the bench is used. To complete the SF-1020 calibration check, a test orifice plate supplied by the manufacturer is used. This plate has one 1.875" and one .312" hole in it.
Operate the flow bench with the test orifice plate in place and adjust the pressure differential control setting and intake flow range to each of the values below. The measured flow should match the corresponding flow specified by the manufacturer with the test orifice in place. Perform the leak check first. To perform a leak check, use the rubber stoppers to plug the holes in the orifice plate. If any of the readings are out of tolerance the problem must be corrected before testing. This daily check will be documented in a log.
Filter Element Test Procedures
When testing filters, it is imperative to select the proper test fixture or adapter that is compatible to the filter shape and size. It may be necessary to fabricate or source the fixture for new element configurations. Additional steps may be necessary to insure that the element is fully sealed to the test fixture and no air leaks exist around the base or any openings (e.g. holes for mounting or fittings).
It is important to flow the filter in the correct orientation as to the direction of designed air flow. This is the direction of air moving from the dirty side to the clean side of the element.
To determine the appropriate flow range for the filter under test, a preliminary flow test must be performed. Select intake flow range #10 (1000 cfm ). Start the flow bench motor and allow the test pressure to stabilize at 1.5" H2O. Observe the cfm reading on the digital readout. Shut off the flow bench motor and select the intake flow range that is one step higher than the preliminary test reading.
Round Filter Test Procedure
When testing round air filters, entry base plates manufactured with a .250" entry radius will be installed on the air intake duct of the SF-1020. A base plate will be selected with an entry diameter closest to the inside diameter of the filter. The filter to be tested is centered over the hole in the entry plate. A corresponding diameter, 0.250" thick, aluminum top plate is used to seal the top of the round air filter.
The top plates have a .125" hole in the center to incorporate a Pitot/static pressure tube to read the static pressure inside the filter element. It is important to note that the static pressure is measured through the holes in the tube that are around the circumference about an inch from the tip and the static pressure tap from the SF1020 is connected to the static pressure tap on the side of the Pitot tube. The Pitot tube tap on the end of Pitot tube is to be capped. Care must be taken to avoid clogging any of the holes in the Pitot tube as this will adversely affect the accuracy of the device.
The Pitot tube tap on the end of Pitot tube is to be capped. Care must be taken to avoid clogging any of the holes in the Pitot tube as this will adversely affect the accuracy of the device. The Pitot tube is inserted into the hole of the top plate to a depth of approximately 1" below the top of the filter element and the area around it sealed with a bit of clay. To measure the flow, set the SF1020 Bench to a fixed 1.5" H2O differential pressure and select the appropriate intake flow range that was derived from the preliminary test above. Turn on the bench blower fan, allow the readings to stabilize. The operator can then freeze the digital display reading at exactly 1.50" H2O and record the cfm reading.
Flat Panel Test Procedure
To test flat panel air filters, a panel filter test fixture has been fabricated. The plenum of the fixture measures 17" long x 10.5" wide x 5.75" deep. The bottom of the box has a 9" diameter hole with a 0.500" entry radius. The panel filter air box will be installed on the air intake duct of the SF-1020. A Pitot/static tube is positioned in the lower corner of the plenum. The top of the box features 4 adjustable slides to accommodate various size panel filters.
The panel air filter to be tested is to be placed on in the air box and the slides adjusted to provide a positive seal on all 4 sides. For panel filters that are not rectangular or are multi sided, care must be taken to seal the entire filter perimeter to the test fixture so there are no leaks. Connect the static pressure tap of the SF-1020 to the static pressure tap on the side of the Pitot tube. The Pitot tube tap on the end of Pitot tube is to be capped.
To measure the flow, set the SF1020 Bench to a fixed 1.5" H2O differential pressure and select the appropriate intake flow range that was derived from the preliminary test above. Turn on the bench blower fan, allow the readings to stabilize. The operator can then freeze the digital display reading at exactly 1.50" H2O and record the cfm reading.
Conical and Universal Clamp-on Test Procedure
Accurate air flow and pressure drop of conical and universal clamp on air filters, in which the base of the filter is molded into the filter assembly and cannot be removed, is difficult to measure because the clamp on base is usually the most restrictive part in this type of filter.
Therefore, K&N has chosen to measure the static pressure of these types of filters by inserting a static pressure Pitot tube into the central portion of the filter base where the filter clamps to the tube or throttle body.
When testing a conical or universal clamp-on filter, various small base plate adapters manufactured with 2" to 6" diameter tubes will be installed on the air intake duct of the SF-1020. A base plate adapter will be selected with an entry diameter that matches the diameter of the filter flange.
In preparation for testing, a Pitot of the proper length will be inserted through the adapter tube and adjusted so the static pressure ports are located at the flange of the filter as near to the center as possible. The filter is then installed on the adapter and the neck or clamping surface, if one exists, will be tightly clamped to the adapter base. It may be necessary to use a bit of clay or tape to seal irregularities to ensure no leakage.
It is important to note that the static pressure is measured through the holes in the tube that are around the circumference about an inch from the tip and the static pressure tap from the SF1020 is connected to the static pressure tap on the side of the Pitot tube. The Pitot tube tap on the end of Pitot tube, if so equipped, is to be capped. Care must be taken to avoid clogging any of the holes in the Pitot tube as this will adversely affect the accuracy of the device.
To measure the flow, set the SF1020 Bench to a fixed 1.5"H2O differential pressure and select the appropriate intake flow range that was derived from the preliminary test above. Turn on the bench blower fan, allow the readings to stabilize. The operator can then freeze the digital display reading at exactly 1.50" H2O and record the cfm reading.
AIR FILTER EFFICIENCY TESTING
The air filter industry uses the ISO 5011 testing protocol when testing filtration efficiency and dust capacity. The test protocol calls for the introduction of a measured amount of "test dust" into the air filter at a selected airflow rate. The test is then terminated after the filter reaches a selected level of restriction (terminal test pressure). The test protocol then measures the percentage of dust retained by the filter (efficiency) and the total amount of dust held by the filter (capacity).
The ISO 5011 protocol allows for flexibility in test design and choice in the variables selected for the test. This means that you can change the grade of test dust, the airflow rate, the beginning and end points of the test, and other factors while still being in conformity with the protocol. For example, the filter can be tested in a special “test housing” or in the factory air box. As you can see, the ISO 5011 test protocol it is not an absolute test or standard; it is meant to help engineers design air filters by holding conditions constant while one variable is changed to measure the change impact.
If all the variables are consistent between two tests, the results can be used to compare the filtration capabilities of two air filters in a laboratory setting under specific controlled conditions. However, any filtration measurement will only be meaningful if it includes disclosure of the test variables that were selected, such as grade of test dust, airflow rate and terminal test pressure.
Because the ISO 5011 protocol uses fixed airflow and is often conducted with the air filter in "test housing," it is not intended to develop a filtration number you will experience in actual use. While in a vehicle, an air filter will experience a range of operating conditions, airflow and dust feed rates, etc.
Under the parameters of the ISO test, the user may select the grade of test dust used. The content of the two most commonly used types of ISO test dust for air filters are as follows:
K&N operates an in-house filtration test lab with two different testing machines built in consultation with Southwest Research Institute, one of the pre-eminent testing companies in the world. Most of the filtration testing they perform on their air filters is performed in their lab that operates on a year round basis. Occasionally, they send air filters out for testing with an independent lab, either to confirm their in-house testing or to reduce the capacity requirements on their lab.
They perform tests of filters both in the factory air box and in SAE/ISO recommended test housing fixtures. Their goal is to design filters with the maximum possible airflow achievable while providing guaranteed engine protection.
Their actual air filters when tested generally demonstrate a cumulative filtration efficiency of between 96% and 99%. All this testing their do allows us to guarantee their air filters provide all the protection your vehicle will ever need.
PRODUCT VIBRATION TESTING
Engineers at K&N use a vibration test stand to put extreme stress on filters, filter assemblies, and air intake parts. The vibration stand is a three axis machine, designed for vertical, horizontal and lateral testing. Frequencies and amplitudes are set for the test then acceleration data is provided and recorded throughout the test. The lateral and vertical functions are similar to going up and down a bumpy road, while the horizontal function is milder. The three profiles are different but effective in determining product quality in simulated driving conditions. Eighteen days on K&Ns state of the art vibration stand is equal to 486,000 road miles. K&N is able to make sure enough flexibility is built into their products by testing, and modifying the design, as necessary, to produce a product that lasts in real use.
K&N stands behind its products. The vibration stand is another tool used at K&N to make sure products meet the expectations of consumers.
One of K&Ns core purposes is to produce quality products that perform as promised. To help ensure this K&N has a section of its research & development laboratory devoted to testing product wear and tear using a vibration stand to duplicate real world conditions.
MASS AIR FLOW SENSOR STATEMENT
Every stock replacement air filter they sell comes with this sticker, which they advise consumers to place prominently on their air box. The sticker is to alert service technicians that they should not throw away your K&N air filter because it will last for the life of your vehicle. When service technicians see this sticker it means "STOP SELLING THIS CUSTOMER DISPOSABLE AIR FILTERS OVER AND OVER." In their opinion, this is why some dealerships or service providers may attempt to discourage a consumer from using a K&N air filter or worse blame a vehicle repair on their lifetime air filter. Most dealerships provide excellent service and fulfill car warranty obligations without issue, argument or tardiness. The rest of this discussion is about a minority of dealerships who are either misguided or misinformed.
They are aware of the "urban myth" (K&N News Story) created by a few dealerships that a vehicles MAF sensor can be contaminated by K&N filter oil. No evidence has ever been provided to support this "myth" and years of diagnostic testing by K&N has shown that not only is this allegation not real, it is not even possible. In their opinion, it is an excuse for a dealership and/or the vehicle manufacturer to avoid a legitimate warranty repair. In the last 4 years, they have sold over 10,000,000 lifetime air filters and received only a few hundred calls from consumers who are having dealership or service provider challenges. They believe that Dealerships or service providers real incentive may be to discourage the use of reusable products so they can sell disposable products over and over. In order to provide consumers with added comfort that they will not be placed in a bad position by an improper warranty denial, they offer their Consumer Protection Pledge.
Mass Air Flow Sensor Investigations
No dealership or service provider, when contacted, has ever been able to provide us with evidence to support this "myth," and in fact, their investigations have revealed that even authorized dealerships are simply speculating and do not have the test equipment necessary to know whether the sensor has failed or why. In the last 7 years, they have had more than 300 actual sensors sent to us by consumers with documents showing dealerships claimed their product had caused them to fail. Microscopic, electronic and chemical testing revealed that none of these sensors were contaminated by K&N oil (K&N Detailed MAF Sensor Test Results). What is perhaps the single biggest clue to what is going on is that over 50% of these sensors sent to us were not broken in the first place for any reason. Click here for more information on how this may happen.
The oil treatment on their cotton is very small (usually less than 2 ounces) and is a critical component of their filtration technology. There is nothing unusual about the use of oil as a tacking agent to improve air filter efficiency. In fact, certain Ford Motorcraft and Fram disposable air filters are treated with oil. This makes us wonder if it is only the oil treatment from reusable lifetime air filters that is alleged cause a vehicle problem? The idea that oil comes off their filter throughout its life is truly ridiculous. Just like oil treated disposable air filters, once their oil is properly and evenly absorbed through the cotton, no oil will come off, even under extreme engine conditions. They have even conducted a test with an over oiled K&N air filter in which they flowed 1,000 cubic feet of air per minute for over twelve hours (few cars or truck could generate even 500 cubic feet of air flow). The use of an absolute filter confirmed that no oil came off the K&N filter tested, even in these harsh conditions.
They have tested many MAF sensors claimed to be damaged. They can fully diagnose their condition and likely cause of failure. For a full discussion of their MAF sensor test protocol and findings, see K&N Mass Air Flow Testing Results and Findings.
ESTIMATED HORSEPOWER GAINS AND K&N DYNAMOMETER TEST RESULTS
K&N Estimated Horsepower Gains
K&N provides estimated SAE corrected horsepower gains that are based on actual dynamometer testing for a specific or similar vehicle. The actual horsepower increase a consumer will receive will vary depending on such things as vehicle condition, fuel, weather and other circumstances. It would be impractical to test every possible vehicle configuration or year in which a particular engine may be used; therefore, many of their estimates are based upon similar engine/vehicle/year dynamometer testing that they believe to be representational for the vehicle listed.
K&N Dynamometer Test Results
K&N utilizes an inertial dynamometer (dyno) to determine the estimated SAE corrected horsepower of their intakes kits and OE replacement air filters. This type of dyno does not actually measure horsepower, but rather measures acceleration. This measured acceleration is then multiplied by the mass of the drum (a constant mass) to obtain the force being applied to the drum, or in other words, the interface between the vehicles tires and the dyno drum. Now that the force at this point is known, determining the torque is straightforward. The torque is calculated by multiplying the calculated force by the radius (again a constant) of the dynos drum.
Now, torque is very simply and mathematically related to horsepower by the following equation:
Horsepower = Torque x RPM /5252
From this equation, the SAE corrected horsepower can be determined.
According to the above explanation, the only variable being measured by the dyno is the acceleration of the drum. There are no adjustments (calibration) to be made by K&N on either the two-wheel or four-wheel drive dyno. The mass of the drum(s) is determined at the factory before shipping the dynamometers to K&N and the mass of the drum(s) are imbedded into the software. K&N does not have the ability to modify or adjust these values.
Furthermore, there are several factors that can affect the SAE corrected horsepower values as measured by K&N or at any other dyno facility. Some of these factors are:
Consistency of test parameters
Tire pressure
Fuel octane rating
Vehicle condition
The atmospheric conditions (dyno correction factors can vary from engine electronic correction factors)
K&N has noticed that SAE corrected horsepower values will vary from day-to-day, while testing the same vehicle, due to the manner in which the vehicles on-board computer adjusts for varying climate conditions. In other words, if a vehicle is tested at sea level on a sunny and warm day, the dyno will apply a SAE correction factor to adjust the conditions to a standard temperature and pressure (STP) and the vehicles on-board computer will also apply certain set of operating parameters. If that same vehicle is tested at a high altitude, on a rainy and cold day, the dyno will again adjust to STP while the vehicle may adjust to a different correction factor than it did on the sea level test. Furthermore, some vehicles have required almost a 100 miles be logged on the vehicle in order to allow the on-board computer to reset itself to obtain accurate power readings.
While K&N pays close attention to these many factors, and is patient while performing dyno tests, they are not in the position to scrutinize the many facilities that perform dynamometer testing for the general public. Furthermore, they certainly do not have enough information to make a judgment on the validity of these tests.