K&N air filter

[JonathanM]

Surely it isn't surface area that is the issue with airflow, but with how resistant to airflow the materials used in the filter are? The limits on a filter will be down to the induction system either side of the filter. Removing an air filter completely from an airbox will improve airflow, however the the variable here isn't surface area - which in effect remains the same in the airbox whether the filter is there or not - but the nature of the filter element itself.


57's are possibly a little too exposed for use in a 4x4 that is used for greenlaning or off road, due to the mud & carp splashed around the engine bay - can accumulate and reduce airflow, I think Sharkie had a problem along these lines when he had an induction kit fitted.

the reason manufacturers won't fit cotton gauze filters is likely down to cost, plus they must have one eye on the replacement intervals of a standard paper element vs a reusable & cleanable one.

 

[(RIP) PLANK]

well if you were using the same materil to make it from i would agree, but there lies the difrerence, two different substances of the same size have two different ses of charecteristics, ie, a plank and a slab :lol:

i wuld think manufacturers stick with paper elements as they are cheap and easily replaceable, no messy cleaning etc required.

ans i assume some of the things manufaturesrs say must be true? or they would all be in court, K&N is american at the end of the day and they sue each other over everyhting :lol:

fo rme the main thing is it is a cheap and easy way to save cash in the long term and if they only imprve matters by 0.5% with the MPG of 4x4's and the cost of fuel it will soon start to make up for the price diference!

 

[Whatmot]

Surely it isn't surface area that is the issue with airflow, but with how resistant to airflow the materials used in the filter are?

thats partly what im saying. if two filters have the same surface area, only one is more restrictive then the other, the more restrictive one is going to be exerting more 'resistance' on the air flowing through it then the other. for the sake of argument, filter B is twice as restrictive as filter A. if the same amount of air is flowing through both, filter B, in an ideal world, would be creating twice the resistance as filter A. if you then double the surface area of filter B, the resistance to the air would be spread over double the area, therefore the resistance acting on the air flowing through it would be the same on both filters. thats the way i see it, and im guessing thats why larger air filters like the k&n 57i kit are popular

57's are possibly a little too exposed for use in a 4x4 that is used for greenlaning or off road, due to the mud & carp splashed around the engine bay - can accumulate and reduce airflow, I think Sharkie had a problem along these lines when he had an induction kit fitted.

point taken, but then on the other hand, k&n's can be washed/cleaned and then reused after respraying them. i havent made my mind up yet, if i do get one ill just see how it goes

the reason manufacturers won't fit cotton gauze filters is likely down to cost, plus they must have one eye on the replacement intervals of a standard paper element vs a reusable & cleanable one.

i was aware of that, but that wasnt the point of my argument. i was trying to say that if paper element filters were not up to the job of cleaning the air intake, why would car manufacturers fit them to there cars, it onkly reduces the life of the engine, which takes more cars off the road and which would surefly make them look worse.

anyway, like ive already said thats just my opinion

 

[dubburke]

i have just bought a 2nd hand one with low mileage on ebay for £15 inc postage, as i needed a new air filter anyway

 

[(RIP) PLANK]

having fitted a couple of K&N recently, th direct replacement type, it is worth noting that!

there is a lot less of the fiter material than the original paper ones! I think there is so much paper in the paper ones it is this that impedes the air flow!

and again i am inclined to agree with the experts at K&N. after all you have to trust some body some times dont you? :?

 

[NNMan]

there is a lot less of the fiter material than the original paper ones!

Which says to me they let more crap through!

 

[JonathanM]

Surely it isn't surface area that is the issue with airflow, but with how resistant to airflow the materials used in the filter are?

thats partly what im saying. if two filters have the same surface area, only one is more restrictive then the other, the more restrictive one is going to be exerting more 'resistance' on the air flowing through it then the other. for the sake of argument, filter B is twice as restrictive as filter A. if the same amount of air is flowing through both, filter B, in an ideal world, would be creating twice the resistance as filter A. if you then double the surface area of filter B, the resistance to the air would be spread over double the area, therefore the resistance acting on the air flowing through it would be the same on both filters. thats the way i see it, and im guessing thats why larger air filters like the k&n 57i kit are popular

57's just remove all of the restriction from the airbox & associated piping. Yes, bigger filter results in more surface area, but it is the open nature of an induction kit that ultimately results in greater airflow. Plus more noise! & lots of it!

 

[Ogri]

Hi,

This makes interesting reading:

http://www.knfilters.com/filter_facts.htm

Some of it may well be corporate rubbish but it gives a small insight into the technical side of filtration.

Ian.

 

[(RIP) PLANK]

there is a lot less of the fiter material than the original paper ones!

Which says to me they let more crap through!

not neccesarily, if the filter material is better quality, and dont forget they use oiled elements to catch fine particles not just dry paper!

truth is unless you run tests you will never know, the people at K&N have run the tests and offer a pretty good guarantee, and i am prepared to take a chance on them.


when yo take you car in for service the garage will just get the filter from the cheapest supplier and stick it in, job done. So surely taking the time to make an informed choice of a quality product is better?

 

[jace]

think the "pores" are bigger on k&n but the oil you spray on grabs the dust etc,older cars used to have oil bath air filters no paper elements

 

[Deleted Member S]

Alot of the cars i've had in the past i've fitted K&N filters with good results :smile: & will be fitting one to the T2 later in the year. After six months of having my first one fitted I was shocked at how dirty it looked compaired to the old standard one, so it must have been doing it's job really well

 

[NNMan]

Well plank, I hear what you are saying and would like the Idea of one but When listening to sellers talk of wonderful products I do wonder these days, its easy to say your product is best and draw a wee graph to prove it. I have heard that they arent so good for every day diesels.

As for services I do them my self. :wink:

 

[jace]

i didnt notice any boost in performance with maverick i liked k&n for two main reasons long life and it highered the air intake away from any potential water hazard!
http://www.potn.co.uk/k&n_c5206_2282.htm

 

[rsaddo]

K&N filters are the dogs danglys ive used allsorts over the years and with crap results,my RS escort has had a panel filter in it for 5 yrs 40 thousand miles it doesnt get used much but when its on the road it gets a proper spanking it runs perfect all the time infact i gained 10bhp from this filter and air box mods alone.
57i kits are for chavs in weedy cars who want them to sound better,without isolating it from the engines heat which kinda defeats the object :roll: once again my rs lost just over 20bhp and pretty much the same in torque with a 57i with a cold air feed to it to
Id defo use k&n panel filters wouldnt bother with induction kits they are a gimmick an expensive one at that