Unbiased air filter efficiency -vs restriction testing?

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Excuse me if this has been discussed before and feel free to point me to the link(s).

We have a ton of ongoing discussion and review about the performance of oil filters. I've only been able to find one review online that looks unbiased that tests a variety of air filters comparing their efficiency -vs restriction, and this study is almost 10 years old: https://bit.ly/2ZoCa4Z

Is anyone aware of any such tests that are more recent?

Could one contact a given manufacturer and ask them for this type of data, much like we can for oil filters? Do manufactures perform such tests and offer this to consumers?

Thank you,
Ed
 
This is the only one I can recall:

https://www.thedieselpageforums.com/tdpforum/showthread.php?t=11674


SPICER
Location: MILWAUKEE
Posts: 72


On another diesel forum the members banded together to conduct an independent study regarding air filters for the Duramax Diesel. There is a lot of marketing hype surrounding certain aftermarket air filters and we wanted to know if the filters could stand up to their claims. Claims of "superior" filtering ability and dirt holding capacity are among some of these claims. Additionally, many filters are claimed to allow for "better" air flow giving you more horsepower.

This claim of better flow giving more horsepower is a debate all its own, but dyno tests run with a paper filter vs. NO FILTER AT ALL have shown NO INCREASE IN POWER OUTPUT. Therefore a filter with "better flow" will not only give you no increase in performance, it will also let in a lot of dirt while doing it.

The following data is provided by Testand Corp. in Rhode Island. Testand makes the $285,000 machines that perform the SAE J726/ISO 5011 air filter test standard. Any air filter that wants to be tested for performance and efficiency uses this test.

These tests cost $1,700 per filter when done by an independent laboratory.

Testand Corp. was interested in the comparison study and agreed to do the study for us.
Every filter listed was tested in an identical manner according to the SAE/ISO test standard; Here are the results:

In the order of EFFICIENCY (ability to filter dirt) the results are as follows:

FILTER % EFFICIENCY

AC Delco OE 99.93%
Baldwin paper 99.72%
No name pargain paper 99.32%
AFE Pro Guard 7 panel filter 99.23%
WIX/Napa Gold 99.03%
Purolator paper 98.73%
Amsoil, new style 98.63%
UNI 97.93%
K&N 96.80%


FLOW RESTRICTION from best to worst. Remember, 27.7 inches of water = 1 psi. So, 1 inch of water = .036 psi. The worst (AC Delco) at 6.23 in. water and the best (K&N) at 4.54 in. water is a difference of 1.69 in. of water or a "whopping" .0608 psi. Virtually negligible.

In order from least restrictive to most:

FILTER RESTRICTION in inches of water

K&N 4.54
Mystery bargain 4.78
AFE Pro Guard 4.99
Purolator 5.05
WIX/Napa Gold 5.06
UNI 5.40
Baldwin 5.71
Amsoil 5.88
AC Delco 6.23


DIRT HOLDING CAPACITY. From best to worst. This is the AMOUNT of test dirt it took to create an ADDITIONAL 10 inches of restriction. At that point the test is terminated. This is an indication of HOW LONG a filter is good before it must be cleaned or replaced.

FILTER Dirt Holding Capacity

AC Delco 573.898 grams
WIX/Napa Gold 447.366 g
Purolator 388.659 g
Baldwin 388.154 g
UNI 374.638 g
Mystery bargain 350.402 g
AFE Pro Guard 7 232.516 g
K&N 211.580 g
Amsoil 196.323 g


TOTAL DIRT PASSING THE FILTER DURING THE TEST. This is how much dirt your engine will take in if you use the filter for the duration that would cause the filter to become "dirty" enough to need replacement or cleaning. The "Dirt Passing The Filter" is the dirt collected by the "POST FILTER" during the SAE/ISO test.

In order from best to worst, the filters performed as follows:

FILTER DIRT IN GRAMS PASSED

AC Delco 0.4g
Baldwin 1.1g
AFE Pro Guard 7 1.8g
Mystery bargain 2.4g
Amsoil 2.7g
WIX/Napa Gold 4.4g
Purolator 5.0g
K&N 6.0g
UNI 7.9g

NOTE: During the test the Purolator was reported to have had a seal failure which gave it higher than expected dirt passing.

I hope this data is as eye opening for you as it was for me. SPICER
 
Far more important at keeping engine wear especially cylinder bore wear to a minimum than the oil filter IMO. Along with a tight PCV/crankcase vent system and dipstick tube seal will keep most engine damaging particles out.
 
Originally Posted by Trav
Far more important at keeping engine wear especially cylinder bore wear to a minimum than the oil filter IMO. Along with a tight PCV/crankcase vent system and dipstick tube seal will keep most engine damaging particles out.



I think you are correct Trav... Prevention beats the cure.

I hypothesize that the Asian car manufacturers actually source very high efficiency air filters... For your stated reason. And why they have OEM oil filters that are lower than expected oil filter efficiency.
 
This is a good discussion on air filter efficiency and I appreciate those who contributed test results and Trav's real world observations. From SAE paper #970556, Filter Performance Requirements for Engine Air Induction Systems, by Neville Bugli, comes the following quotes: "Engine Air Inlet is the Major Source of Harmful Contaminants" so high quality air filters properly installed and tight induction systems really are critical for optimizing engine life.

"Today, in addition to the overall efficiency, the end user also specifies an initial efficiency requirement for engine intake filters. It has been well demonstrated that clean air filter media exhibits a much lower collection efficiency compared to a loaded filter. Even small amounts of contaminant loading dramatically improves the collection efficiency of the air filter. Engine designers are increasingly concerned about the amount and type of contaminant that could be ingested by the engine."

"Initial efficiency is the key filtration performance measure to determine how well the air filter is protecting the engine. It has been well demonstrated that the initial efficiency of the filter is significantly lower when the filter is new and clean. The efficiency generally builds up after the first 5 - 15% of its useful life. Studies have shown that there is a very strong relation between filter removal efficiency and engine wear. For normal driving conditions it is recommended for engine air filters to have an initial gravimetric efficiency in the range of 98% to adequately protect the engine."

"Generally the overall efficiency is significantly higher than the initial efficiency and is strongly dependent on dust loading characteristics of the media. For both the dry and treated paper media the overall penetration (1- overall efficiency) values dropped by a factor of about 2 or by a factor of 3.3 for synthetic media. The recommended overall efficiency for normal driving conditions is generally 99+% to adequately protect the engine."

Thus we see that filter efficiency is not constant over the life of the filter and to make a valid comparison the testing methods and reporting data must be comparable. For optimal engine life, it is important to not change air filters too early. A filter restriction gauge is the most reliable method of monitoring filter life and these can be retrofitted if you want to optimize engine life.
 
Changing air filters too frequently is actually detrimental. Jim Allen noted that when he toured a major filter maker, they stated that 90% of all particulate passed by an air filter will happen in the first 10% of it's life cycle. Unless you live in an extremely dusty area, air filters can last far, far longer than most people think.

But it's hard to combat the sales jibberish of those quickie lube places that trot out the filter element to the soccer moms and say "See how dirty this is! It needs replaced." Long, long ago, I used to frequent an oil-change place. I got OCIs every 3k miles, and by gosh they came out every visit to tell me I needed a new air filter, too.

I've learned a LOT since then.
 
So this begs the question: If you wanted to install a restriction gauge/filter minder, how would tou knkw restriction limit would to go for? It looks like Donaldson has them in 15, 20, 25, and 30" H2O versions. What would be the best one to get for say, a passenger V6?
 
The gauge doesn't care if the engine is a little 125cc engine or if its a 855ci N14, all the gauge reads is the restriction(at WOT on a gas engine). I use the Wix gauge that goes to 25" and I change the filter out when the gauge reads 15" of restriction. Have used this gauge on every car and pickup I have owned for the last 35 years.
https://www.summitracing.com/parts/wix-24801/overview/

The gauge locks at every point going up to 25" not just at 25" So if you have a diesel I would run it to 25" but on a gas engine I'd change the air filter out by the 15" mark.

Rod
 
10" is the generally accepted upper limit for a gas engine, and some people run a diesel filter to 25".

Unless you operate in a ridiculously dirty area, you'd be amazed how long it takes to plug a filter. The minder will make you realize how much time you wasted worrying about or changing filters nowhere near their limit.
 
From the Document "Effect of Intake Air Filter Condition on Vehicle Fuel Economy" prepared by Oak Ridge National Laboratory for the Department of Energy (an excellent study) : " In Engineering terms, the service life of an air filter is commonly defined as a level of restriction which results in a pressure drop across the filter of approximately 2.5 Kpa (10" of H2O) more than the pressure drop of the new or clean filter."
On my vehicles this equates to about 15" H2O total restriction on the gauge since the gauge reading includes the restriction of the inlet ducting. As others have correctly noted, for vehicles operated mainly on paved roads, filter life in miles is easily 60 to 100 thousand miles. As I have said before, installation of an filter restriction gauge (Napa #4801 has 25" H2O DP range) is a win-win situation for a vehicle owner because it gives you the confidence to save money on unnecessary air filter changes, reduces wear on your engine because of improving air filter efficiency with use and allows you to teach the quick-lubes, and others, to keep their hands off your air filter.
 
Originally Posted by compratio10_5
From the Document "Effect of Intake Air Filter Condition on Vehicle Fuel Economy" prepared by Oak Ridge National Laboratory for the Department of Energy (an excellent study) : " In Engineering terms, the service life of an air filter is commonly defined as a level of restriction which results in a pressure drop across the filter of approximately 2.5 Kpa (10" of H2O) more than the pressure drop of the new or clean filter."
On my vehicles this equates to about 15" H2O total restriction on the gauge since the gauge reading includes the restriction of the inlet ducting. As others have correctly noted, for vehicles operated mainly on paved roads, filter life in miles is easily 60 to 100 thousand miles. As I have said before, installation of an filter restriction gauge (Napa #4801 has 25" H2O DP range) is a win-win situation for a vehicle owner because it gives you the confidence to save money on unnecessary air filter changes, reduces wear on your engine because of improving air filter efficiency with use and allows you to teach the quick-lubes, and others, to keep their hands off your air filter.


It also keeps them from stripping out the screws that hold the top half of your air filter housing in place. Some manufacturers wised up and put tension clips instead of screws. Both a lube place and a dealer did it too me using powered tools instead of by hand. I finally had to install brass inserts and #8-32 machine screws to keep it from stripping out again.
 
Originally Posted by compratio10_5
From the Document "Effect of Intake Air Filter Condition on Vehicle Fuel Economy" prepared by Oak Ridge National Laboratory for the Department of Energy (an excellent study) : " In Engineering terms, the service life of an air filter is commonly defined as a level of restriction which results in a pressure drop across the filter of approximately 2.5 Kpa (10" of H2O) more than the pressure drop of the new or clean filter."
On my vehicles this equates to about 15" H2O total restriction on the gauge since the gauge reading includes the restriction of the inlet ducting. As others have correctly noted, for vehicles operated mainly on paved roads, filter life in miles is easily 60 to 100 thousand miles. As I have said before, installation of an filter restriction gauge (Napa #4801 has 25" H2O DP range) is a win-win situation for a vehicle owner because it gives you the confidence to save money on unnecessary air filter changes, reduces wear on your engine because of improving air filter efficiency with use and allows you to teach the quick-lubes, and others, to keep their hands off your air filter.


Yup, my S2000 has 8" with a new filter and I changed out my old one at 90k miles. Not because of restriction(don't do much off roading, at least I try not to) but do to age. My '13 Jeep does get up to 15" (3" to 4" with new filter) after many miles of off roading. I think I got 42k miles on the last air filter.

Rod
 
I can see a restricted air filter reducing PEAK HP but not fuel economy (your right foot and the mass air pressure / flow sensor will compensate for that).

Changing more frequently does have an advantage: if a critter is living in your air box you get to evict it earlier / more frequently.
 
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