How well do K&N air filters work?

This is a question which has been long debated. There are those who swear by K&N filters, and many who swear at them. From ‘Autoblog:’:http://www.autoblog.com/entry/1234000600057664/

Fortunately, a Duramax owner tired of the lack of scientific evidence pursued a path of testing that eventually ended with a lab performing the ISO 5011 procedure on a number of replacement air filters.

Read the ‘full test results here’:http://home.usadatanet.net/%7Ejbplock/ISO5011/SPICER.htm. The gist of the tests is:

The K&N and UNI filters were far less efficient at trapping dust, and note that they lose their flow advantage after filtering about 180 grams of dust.


From the ‘Impala SS Forum’:http://impalassforum.com/noncgi/ultimatebb.php?ubb=get_topic;f=8;t=015894

bq.. any cotton oil gauze filter is not going to filter as well as a paper filter period. Cotton gauze offer flow over filtering. More or less it’s a Cold air intakes new intake tract or location that will see the gain. If they made a paper cone filter to fit the Raiss I’d prolly run it.

Note from reading on the oil forums a dirty K&N or similiar filters better than a clean one. Also note that K&N is considered garbage in the performance filter area due to it’s poor construction, lack of pleats, and the ability to see light through the filtering element when held up to the light. S&B by far is considered to be a far superior filter to K&N. Personally if you don’t drive in really dusty conditons then use whatever you want, but if you’re in a heavyily dust enriched envir. then use paper.

It has to be said, bolting on a K&N filter kit does increase horsepower – but not because of the less restrictive filter, but because generally people end up changing the entire intake pipe to the manifold with the far less restrictive one which comes with the K&N kit for their car – so the reports of increased horsepower are true in those cases. But, just changing the filter only, according to any forums reports doesn’t do anything.

Most of the locally built jeeps have a filter box too small for the engine – so on these cars removing the filter box and attaching a K&N filter does increase performance – on turbo engines it can be up to 25%! Again though, it was the removal of the restrictive filter box from the air intake which caused the increase in horsepower, and not the addition of the cotton filter.

The general consensus seems to be that paper filters are the best when it comes to filtration, so for dusty conditions like we have in Pakistan a cotton gauze filter like the K&N is a bad idea.

further reading

  • ‘An interesting discussion at a BMW forum’:http://member.rivernet.com.au/btaylor/BMWText/technical/K&NFilters.html
  • ‘TWMX All Access: K&N Engineering’:http://www.transworldmotocross.com/mx/features/article/0,13190,1083863,00.html
  • ‘Air Filtration and Flow Test’:http://www.bobistheoilguy.com/airfilter/airtest1.htm :: Another comprehensive test.

12 thoughts on “How well do K&N air filters work?”

  1. Dear Sir

    The write up is really good. I need to ask one question that is am living in India and i own a 150cc motorbike which is just a commuter (Not a sportbike), as you must be knowing that India is quite dusty and sandy so which will be the best filter for my bike K&N or uni.. Please reply soon waiting for ur answer…

    Thanks

  2. sir u have great knowlege abt the filter stuff,so pls help me on my problem.i hav a honda city 1.3(1999) n ford endeavour-diesel 2.5(2005), i was thinkin of adding k n n air filter to them.but after reading ur write up i think getting it is waste,so now i think of getting the k n n air pipe.does that effect the millege of the car n is there a real diffrence. also how much wud it cos(estimate)…..watin for ur reply thanx!!

  3. jus need 2 know why the hell is it that when i get in2 the k&n filter site … its only given abt cars… is the filter ment 4 cars only … or is there a different version 4 the bikes … i own a bajaj pulsar 180 and am goin 2 get sum serious modifications done 4 it… performance wise… so ..it would be great 2 know which is the best danm fillter k&n has 2 offer ….. in india… and also if it is possible 2 use the bigger more effctive car filter in the bike 4 max bhp output oh ….i also heard that it increases ur mileage 2……is it true….??? really lookin 4ward 2 ur reply…..

  4. i have a 150 cc pulsar dtsi and have already have a K&N air filter for tht but can u suggest any other upgrades available wth K&N for my bike like the oil filter or typhoon…please let me know As soon as possible

  5. I have a 2000 Isuzu Rodeo 4×4 and I did not notice any change as far as gas/patrol consumption is concerned meaning I did not get any better gas mileage but it did add a little bit of xtra horse power though.

  6. i own a pulsar dtsi 150,and i am contemplating on gettin a KNN attached to her,according to the indian conditions what do u suggest,is it really worth ?and does it kill the engin’s life ?

  7. i have a pulsar 150 dtsi .pls give some details about the air filters . which brand to go for;is it really worth ;about the milage . looking foward for your reply

  8. hello sir,

    your article gives a totally new dimension to the general thought of k&n air filters…..

    sir i hav a plusar 150……would u please help me in deciding whether i shud go

    for k&n air filter..

    also brief me about any turbo airfilter(if any) there in the market for pulsar!!

    awaiting your reply….

    thanks!!

  9. hello sir,

    your article gives a totally new dimension to the general thought of k&n air filters…..

    sir i hav a plusar 150……would u please help me in deciding whether i shud go

    for k&n air filter..

    also brief me about any turbo airfilter(if any) there in the market for pulsar!!

    awaiting your reply….

    thanks!!

  10. hi, i have a 2005 dodge durango. i am trying to conserve gasoline, i have a4.7engine im worried about a oil build up on my mass air senser and air flow problems,i am using a drop in filter.

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