Air Filters - whats your preference?

[ISUZUROVER]

"If you read the text you will find that it does - the Amsoil, uni and K&N were oiled."(QUOTE)

ISUZUROVER- I read the info in your text and although it refers to these filters as being the oiled reusuable type I cannot find where in the text does it mention what brand or of how much oil they used on the filters during the testing. This leads my to believe the were tested dry but, I wasn't there so i guess we'll never know. And as i said before, If foam is o bad why have the Japanese being doing it for decades? It can't be to raise money because the top "works" teams are still using foam filters. These companies have the money to spend on R&D so ill stick with them

The ISO test requires the filters to be tested as specified by manufacturers recommendations. So if the manufacturer recommends x ml of a specific oil be applied, then the filters SHOULD be tested in that state, if the tests were conducted properly.

As you said yourself - motorcross engines are lucky to last a few hundred hours - and maximum performance is preferred over maximum longevity. In this case, there is nothing wrong with a foam filter if it is cleaned regularly.

Btw - most engineers working on racing teams have NFI about filtration. I once spoke to an engineer for the ford focus WRC team, and he admitted they had a few premature engine failures (during races) due to filters that were not efficient enough (were made to maximise performance at the expense of dust removal efficiency). Yet the ford WRC team had a huge R&D budget...

Mining and earthmoving vehicles, on the other hand, are expected to last as long as possible, under conditions that are dustier than the average motorcross track. ALL mining and earthmoving vehicles use fibrous filters, not foam filters.

And if anyone cares, on my two Land Rovers, I use:
Genuine Donaldson filters on one (the one with the $$$ engine)
and a finer filter on the other (but in my defence I bought it before i started working in filter R&D and knew how bad they were) - it is still much better than the factory oilbath filter though.

[dirtyGQ]

Far out now you are all worrying me i may have to think for a while if i should put back in my oem nissan filter or stick with k&n ...

[Grimslov]

"Mining and earthmoving vehicles, on the other hand, are expected to last as long as possible, under conditions that are dustier than the average motorcross track. ALL mining and earthmoving vehicles use fibrous filters, not foam filters.

The guys at Berrima diesel made the same comment to me. They virtually insisted that I get rid of the Finer Filter I had in at the time when I took a hilux to them to get the injectors and fuel system checked out. What they did worked for me.

[HotFourOk]

After I read that webpage about the foam filters not getting rid of as many small paticles than a paper one.. i decided to just replace my paper elements... Whats 5-10kw increase anyway... Its a diesel LOL
I want my motor to last like 600,000kms.. I'm not going to jeopardise that for a few kWs.

[LuxyBoy]

Well in the USA K&N guarantee your engine life while running one of their filters so they can't be that bad. I have a mechanic friend that has worked in engine rebuild places and he runs a K&N full-time and that is after seeing the engines that run them so they can't be that bad.
But really it comes down to maintenance if you only oil it once a year it will be shite, however if you only replace your paper one once a year it will also be shite.

[Beastmavster]

Personally I'd rather stop 20 times as much debris getting in my engine and lose 5 horsepower.




Ok..... motorcross engines may use foam filters.... but all Japanese road bike engines use paper and they're the ones after really big power (say 100kw +).

The pump millions into R&D between model updates to gain 2 hp - so why don't they use free flowing foam filters for their sudden free horsepower?

Cmon, tell us why that is?



Motorcross engines only use oiled foam for two main reasons....

1) because the engine life is so short anyway that the wear/damage rates are irrelevant.

2) in a very wet environment the moisture degrades the effectiveness of the paper filter.

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[460cixy]

we used finer filters on some very expencive profesinal turf equipement to try and keep the costs down. biggest most expencive mistake i have ever made. changed back to factory paper and donaldson pre cleaner and no trouble after. being in the turf/earth moveing game working with million dollor excavators scrapers ect all have paper filter with no exception. some machines still use the old oil bath filter where the air is draged throu oil and last for ever after market filters best advice i can give is leave them well alown

[fnqcairns]

Interesting reading but really what is BETTER starts with what the owner wants from the filter.

If breathing at high RPM combined with high oil lubricated parts wear is important then the foam wins hands down -every time!

If standard performance and high internal protection is what's important then stick with the genuine or trade up to one of the premier filter paper makers aftermarket choices.

Anyone who has seen oil analysis's done on engines with oiled filters would be shocked at the contamination these foam filters allow (it's easily tested for). Lots of shiny internal metal in foam filter engines When I was younger I really didn't care about the extra wear I wanted a couple of extra HP near redline, but today the thought of fitting a foam filter to one of my engines fills me with dread and horror to the point I simply would not buy an engine with one on it or that I suspected had one on it in the past.
Today if I ran a foam filter 24/7 I would also run the cheapest woolies oil at 10-15k drains and the cheapest 'any brand' oil filters I could find to 30K before replacement.

The foam filter alone could wipe 40% of the life of an engine no sweat but the above oil and filter regime may only wipe 20% or even less.

Foam = absolutely crap filtration -period!

Cellulose = near best case filtration -period!

Now which is important to YOU cause thats all that matters.

cheers fnq

[Pipes]

Everyone has there own suggestions, so I’ll just add to it. I'm in to new generation diesels & oil filters aren’t good for all the sensors. K&N are good but the computers in these engines are tuned for a certain parameters of air intake. I also saw a filter that goes over the head of a snorkel. That’s another idea as well. Spend the money on raising the air intake. As for me I will be running original air filter in to my new generation diesel.

[bigpat]

I know F1 cars don't have major dramas with dust, but 9 out 10 teams use K&N oiled air filters. These guys spend millions so they can and do investigate all the options, so if they find K&N the best blend of filtration & flow, its good enough for me, regardless of what that graph shows....

[TRobbo]

I've used both finer filter & K&N on my 4bys. Both times the engines died prematurely despite regular maintenance of the filters.
And if your worried about fouling a filter over an extended outback drive - it is easier to carry a paper filter and change it on the way than it is to clean and reoil.
Paper all the way

[Hardy]

I tried a K&N style filter.
MAF sensor had a coating of dust & oil.
Evidence of dust inside inlet tract.

Gone back to OEM paper - concertina design, much larger surface area? Could not detect a power difference or change in fuel consumption. (Rover v8's 2 worst attributes!)
And I now grease around the lip of airbox and where filters sits.
Not to stop water - just dust!


Hardy

[revin]

I wouldnt use a K&N filter on my 4x4 . They flow more due to having bigger holes (microns or what ever there called) so they flow better but will also let more dirt in.

I run a standard air box on my road bike,bought a K&N for it a year ago as was cheaper than a stocky after about 4000k`s I had a look in the air box while doing a service and f**k me if it hadnt let dirt/dust thru, yeah they flow,yeah they help make a lovely induction noise,yeah they can be re-used,but hell no will I ever buy or use one again.

In my Hilux I use standard type air filter,does anybody run a thin film of grease around the bases fo there filters to help seal them ????

[rick130]

I know F1 cars don't have major dramas with dust, but 9 out 10 teams use K&N oiled air filters. These guys spend millions so they can and do investigate all the options, so if they find K&N the best blend of filtration & flow, its good enough for me, regardless of what that graph shows....

yeah, no worries. Just remember an F1 engine only lasts 5-6 hours between rebuilds.......

and FWIW, how much do you reckon Caterpillar, Cummins, MTU Detroit, Iveco, Mercedes Benz Trucks, etc spend on R&D when a customer expects their capital purchase to last 1,000,000km ?

[dirtyGQ]

I wouldnt use a K&N filter on my 4x4 . They flow more due to having bigger holes (microns or what ever there called) so they flow better but will also let more dirt in.

I run a standard air box on my road bike,bought a K&N for it a year ago as was cheaper than a stocky after about 4000k`s I had a look in the air box while doing a service and f**k me if it hadnt let dirt/dust thru, yeah they flow,yeah they help make a lovely induction noise,yeah they can be re-used,but hell no will I ever buy or use one again.

In my Hilux I use standard type air filter,does anybody run a thin film of grease around the bases fo there filters to help seal them ????

I THINK I'LL GO BACK TO PAPER TYPE FILTER ,BUGGER REALLY AS IN A 4.2 DIESEL U NEED ALL THE POWER YOU CAN GET.

[sarg]

I haven't seen a motorcross bike made in the last thirty years with a paper element filter on it! And they spend their lives in the dirt.




Haven't seen an Earthmover made in the last 30 years WITH a foam element either. And they spend their lives in the dirt.

[bigpat]

Point taken regarding the earth moving equipment....

[GRINCH]

i,m running k&n very happy, wouldnt go near finer filters as a mate has a twin turbo pajero that in 1 weekend sucked that much dust threw it distroyed 2 turbos and a $20,000 motor, so hes now gone back to k&N

[ISUZUROVER]

however if you only replace your paper one once a year it will also be shite.

NO - the best thing you can do with your paper air filter is NOT CHANGE it too often.

It may sound counter-intuitive, but it is true.
http://www.outerlimits4x4.com/PHP_Modul ... hp?t=45726


From Caterpillar

Filter manufacturers often say "dirty" filters are more efficient than new ones because dust cake buildup on the surface actually increases filtration.

http://www.cat.com/cda/layout?m=37499&x=7

[ISUZUROVER]

I know F1 cars don't have major dramas with dust, but 9 out 10 teams use K&N oiled air filters. These guys spend millions so they can and do investigate all the options, so if they find K&N the best blend of filtration & flow, its good enough for me, regardless of what that graph shows....

Most F1 teams are switching to nanofibre impregnated fibrous filters. These are the way of the future, as they can have the efficiency of a good quality paper (cellulose fibre) filter, with the pressure-drop of a foam-type filter.

[djr320kw]

know F1 cars don't have major dramas with dust, but 9 out 10 teams use K&N oiled air filters. These guys spend millions so they can and do investigate all the options, so if they find K&N the best blend of filtration & flow, its good enough for me, regardless of what that graph shows....

The problem with this point is the amount of time that would go into making sure it was equally oiled and checked. They employ people to watch the paint go on the cars to ensure that it is done the correct way and will not effect dynamics.

So you could imagine the process they would go about with the air filters.

[ISUZUROVER]

Some info on oiled filters.

Some people seem to believe that having an oiled foam filter as opposed to a dry foam filter magically transforms the efficiency of the filter - that the oil somehow drastically increases the filters efficiency without increasing pressure drop. This is completely untrue. Oiling a filter does three things:

(1) It means that particles are captured in the oil, and not directly onto the filter material - making them easier to clean off later.

(2) It means that particles that have been captured will not be re-entrained (released) back into the air (this almost never happens in an efficient filter anyway).

(3) The oil slightly decreases the porosity of the filter, increasing the efficiency of the filterfor large particles slightly, but decreasing the efficiency for small particles - So depending on the size of the dust in the air, the overall efficiency of an oiled filter may go up or down (compared to a dry one).

The attached graph shows the difference in efficiency between a clean and oiled filter.

[fnqcairns]

Thanks Ben for the info I enjoy your posts, cuts like knife through all the maketing crap used these days to sell stuff to poor buggers like me

To me it's all about obtaining the best possible protection long term without sacrificing performance or enhancing it either (would be nice but- I know dreaming without major airbox mods/replacement etc!)

Anyway in hope I would like your opinion on what is the best and most consistent brand of aftermarket air filter I could buy? and please dont say just buy your particular makes genuine offering or I will puke all over my keyboard

I am about to source a new air filter and would like to cut straight through all the crap as best I can anyway.
Hope that is possible today with air filters.

cheers fnq

[Patroler]

Ok..... motorcross engines may use foam filters.... but all Japanese road bike engines use paper and they're the ones after really big power (say 100kw +).

The pump millions into R&D between model updates to gain 2 hp - so why don't they use free flowing foam filters for their sudden free horsepower?

Cmon, tell us why that is?



Motorcross engines only use oiled foam for two main reasons....

1) because the engine life is so short anyway that the wear/damage rates are irrelevant.

2) in a very wet environment the moisture degrades the effectiveness of the paper filter.

i agree with this, but i was discussing this thread with a mate whose been into and highly competitive on dirt bikes for about 30 odd years (also does his own maintenance) and he thought of another interesting point as to why dirt bikes run foam:

Most dirt bikers wash and oil the filter every ride, foam wont get ruined when it gets wet, paper might, so if you had to buy a new paper filter every time you went for a ride the cost would add up real quick... Also as posted above somewhere, dirt bike engines don't last long and are cheap to rebuild - especially compared to large diesels

Fwiw i run paper filters in my fourbys, used to run foam in turbo cars though (one spent more time apart than together), but a fourby aint a sports car - whats good enough for CAT, Cummins, Detroit etc is good enough for me!

[Hekta]

Anyone wanna buy my K&N filter ?

[zookjedi]

i use paper in my patrol and although they are expensive to replace they don't need to be replaced as often as people tend to change them , i have a filter restriction gage that does the thinking for me , when it gets near the red i change it out , reason for paper just personal choice.

but all the earth moving machines don't use only paper, CAT also have some running a dry fibourous material (feels like rough mohair) , given they are used in the small excavators and skidsteers , which are in dustier enviroments than the majority of haul trucks and loaders as there spinning around at low levels in there own dust .
in saying the above the engines in these small machines are actually perkins with the cat badge .

[ISUZUROVER]

To me it's all about obtaining the best possible protection long term without sacrificing performance or enhancing it either (would be nice but- I know dreaming without major airbox mods/replacement etc!)

Anyway in hope I would like your opinion on what is the best and most consistent brand of aftermarket air filter I could buy? and please dont say just buy your particular makes genuine offering or I will puke all over my keyboard

Donaldson and Mann Filter are the two largest automotive air filter manufacturers in the world. They have the best R&D and make the best quality, most high-tech filters available. Chances are they either make the filter that is in your nissan, or you can buy a replacement filter from them - either way it will be cheaper than buying from nissan, or the same/better quality.

The newest generation of filter elements have cellulose fibres which are combined with a layer of polymer nanofibres. If you can get a filter from this type of media for your application it will be optimal. The nanofibres give the filter media very low flow resistance, but very high efficiency. These filters have the potential to have a much lower pressure drop than a foam filter, but at the same time a higher efficiency than a conventional cellulose fibre filter.

I haven't seen an aftermarket filter from a small manufacturer that is up to the quality or performance of the two brands above.

If you want the best of the best, then fit either a Powercore filter (and housing) from Donaldson, or a Compact Plus housing from M+H with a pico-Flex filter element.

Information on the Mann-Filter chambers and elements are here:
http://www.mann-hummel.com/group/upl...BWSJAIoyuT.pdf

[ISUZUROVER]

i use paper in my patrol and although they are expensive to replace they don't need to be replaced as often as people tend to change them , i have a filter restriction gage that does the thinking for me , when it gets near the red i change it out , reason for paper just personal choice.

That is absolutely the best way to change your filter, only when the pressure drop gets too high.

but all the earth moving machines don't use only paper, CAT also have some running a dry fibourous material (feels like rough mohair)...

"paper" filters are a bit of a misnomer. They are actually cellulose fibre filters. You can make a filter out of any material you can make fibres from. I have filters here at work made from:

cellulose fibres
glass fibres
stainless steel fibres
polyester fibres
polypropylene fibres
etc, etc...

Probably the best filter would be one made of very fine stainless steel fibres. You could make a high efficiency filter that was virtually indestructable and also washable. The only problem is that only one company in the world makes stainless steel fibres fine enough, by a patanted process that takes 3 months from start to finish. No surprise that they are the most expensive filters in the world.

[fnqcairns]

Ben thanks for the information I will begin chasing up something within those brands to suit.
Nano fibres I guess will be out of my price range for a general muckabout vehicle but interesting non the less.

cheers fnq

[-Scott-]

Ben

I read the test report in the link, and it's a bit of an eye opener.

How much do you know about the procedure used? I'm wondering about the oil used in the foam filters. If they're measuring weights before and after the test, are they controlling for any oil which may be blown out of the test filter, and collect in the downstream filter? I spray mine with an aerosol, which I presume contains volatiles. Any idea if it's significant?

Cheers,

Scott