K & N FILTERS

<div class='quotetop'>QUOTE(PhilipA &#064; May 18 2006, 09&#58;39 PM) Quoted post</div><div class='quotemain'>
Altech, I have tested a Range Rover cylinder paper filter for its resistance to the air flow with a &#036;100 Minihelic differential vacuum gauge calibrated to max 30 inches of water.
Up to about 3/4 acceleration its resistance is NIL and at full noise on a 3.9 it is 4 inches of water which is a tiny bit. That is both the filter element and the housing. I took the vacuum reading between the filter and MAF.

Now I havent tested a Disco panel but at low revs I am sure it would be nil unless very dirty. A diesel passes more air at max torque revs but at idle and not full torque it should be only passing a moderate amount or air.
I have found that improved inlet air flow only gives an improvement at absolute maximum air demand eg up a hill flat aand only if the standard filter is too small. Others eg The Toyota V8 forum have tested them on dynos and found a very small improvement in power ONLY at max demand.

Did you read the reports on K&N? I had one , and found fine dust in my MAF after a trip to Jerilderie via Wombeyan Caves. If its an 300Tdi auto with a MAF, be careful you do not foul it .

It should do no damage on a straight mechanical 300Tdi except if you travel on dusty roads.

You are entitled to believe in it, but show me the test results before I do.

A reason I now do tests is that I bought a Hiclone on the advice of a friend who swore that he got 15-20% fuel economy improvement. I got zilch when I tested it to and from Sydney to Brisbane.
Regards Philip A
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These are the results you would expect. Look at it this way (petrol engine) - except at full throttle, the throttle valve will offer far more resistance to airflow than any reasonable aircleaner; on a modern engine the ecu will adjust mixture as required, and on an older design without an ecu the carburetter is set up for the standard aircleaner, and so will run slightly leaner at full throttle (which may not be a good idea). On a diesel the airflow is higher, so there will be more loss at all speeds, but it will still be pretty small unless the standard filter is too small or needs service, and the power or economy is not sensitive to the volume of air until full throttle and maximum rpm, when the slight increase in volume will allow more efficient burning and hence power - but how much of your driving is at this point?
John

That is a very interesting report on filters. I do use K & N for the water issue, thanks for the link to the report. And as fare as hiclown goes if it worked as claimed every vehicle manufacturer would fit it as a standard feature?

glen

Wow all this "to K&N or not to K&N that is the question" is very confusing.

I did look at the report but lost interest after the 2nd graph https://www.aulro.com/afvb/

I was thinking of putting one on the Rangie. The only reason I was goin to do it is because it is "cleanable". I find my paper filter (I am running a commodore air filter on top of the WW stromberg carby) is getting dirty very quickly. I had heard that K&N was ok as long as you kept up the maintenance and kept it clean and oiled which I would do after every trip.

After seeing all these comments maybe I better rethink.

I had one on my 300Tdi and my bum dyno couldn't detect any difference whatsoever in performance. Removed it after 20,000km as I was worried about its dust holding abilities, although I'd used them with great success on race cars. Eighteen months later Spicer published those test results on the 'net, then about eighteen months ago I asked Ben/Isuzurover on Outerlimits his opinion on those results after PhilipA posted the link there (Ben's a filtration engineer, currently doing R&D in Germany) and he said it's all technically sound. He's since done and seen results from some independent tests since that have firmed his opinion on K&N's lack of filtering ability.
Check out his latest thread on 'Krap&N filters' on the general tech discussion forum on OL.

Also, I had increased silicon (oxide) levels in my oil with the K&N over a Donaldson paper filter which generally indicates increased dust passing the filter. It wsn't enough to raise a flag at the lab, but it was noticeable.

Jim Attrill on the old LRE board had one fitted to his 300Tdi in South Africa, as did one of his mates, and both engines needed re-honing and re-ringing after using a K&N for 80,000km (IIRC, both engines were well under the 200,000km mark at the time) There were no honing marks left on any bore, he claims they'd been sand blasted nicely.

Fella's, also remember that a dirty filter is a good thing, and that the dirtier it gets, up to the point of too much pressure drop affecting performance, the greater the filters efficiency. (this is basic filtration theory)
Also, if a paper filter is sized correctly, ie. it's face area is such that pressure drop is minimal, (and most nearly all modern cars fall into this category) how can a K&N increase performance ?

I have a Unifilter oiled one on the disco TDi and it seems to work well. Certainly improves performance.
Also just got a Unifilter "sock" for the snorkel head for when it is really dusty - yet to try it.

It is interesting to look at the history of air cleaners. When the motor car first started to become popular early last century, nobody had heard of air cleaners, or, apparently, even thought of them. They were first introduced on tractors, almost as soon as IC engined tractors started being sold around 1900 - visualise a tractor ploughing a dry paddock going downwind at the same speed as a gentle breeze and you will see what I mean! It took over twenty years for this experience to translate to the motor car - to quote from "Automobile Engineering", American Technical Society, 1926 - "the use of air cleaners is rapidly becoming standard on both tractor and automobile". The Ford 'T' for example never came from the factory with an air cleaner. The precipitating factor may have been the adoption of alloy pistons - where two metals of different hardness run in contact with each other the grit gets embedded in the softer metal and it acts as a lap to wear the harder metal.
By the 1930s air cleaners became almost universal. The oiled membrane air cleaners of the K&N type are a throwback to the relatively ineffective ones commonly used in cars in the 1920s and seen today in, for example, my chainsaw. These were mostly replaced by oil bath air cleaners in the thirties as they were more effective and easier to combine the secondary function of silencing the intake (the lack of silencing with K&N filters often gives the illusion of more power). By the 1960s several factors led to the change to paper filters - they are cheaper to build than oil bath cleaners, they are smaller for the same airflow (and space under bonnets was getting cramped at the same time power was increasing), the regular sale of filters helps the dealer's cash flow, quite often the cost of the element is actually less than the oil needed for the oil bath cleaner, and they are quicker and less messy to service.

John

JD, my old Fiat 550 tractor still sports it's original oil bath air cleaner, which I've been meaning to rplace with a Donaldson or Nelson for a while now. A friend borrowed it recently to slash around 30 acres of thistles and I'm not game to check in the filter bowl .....:rolleyes:

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Originally Posted by rick130

JD, my old Fiat 550 tractor still sports it's original oil bath air cleaner, which I've been meaning to rplace with a Donaldson or Nelson for a while now. A friend borrowed it recently to slash around 30 acres of thistles and I'm not game to check in the filter bowl .....:rolleyes:

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The oilbath aircleaner should be quite effective - provided it has oil in it and is not choked up with dust. My 2a still has the original oilbath aircleaner and I see no point in replacing it (but note that one problem with these can be that oil splashed up the central pipe can lead to a buildup of "oil mud" that significantly restricts flow and is not noticed in normal cleaning. Since discovering this I now take the top off and check the central pipe.

John

hmm dunno, the few reports I've heard of weren't too good. Put it this way, a K&N looks much better ;)

One oil industry bloke who is based in Bolivia that posts on an oil forum I've been on for a while had some oil test results out of comparitive Hi Lux's, several using aftermarket oil baths, the others usin OEM paper. The oil bath ones were absolutely loaded, and a couple of the engines were stuffed.

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but note that one problem with these can be that oil splashed up the central pipe can lead to a buildup of "oil mud" that significantly restricts flow and is not noticed in normal cleaning. Since discovering this I now take the top off and check the central pipe.

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yep, found that when I last serviced it over twelve months ago. There was also a fair bit of buildup of muck all the way to inlet manifold. It was the father-in-laws before we nicked it, and servicing has never been his strong suit. Most of the farm equipment hadn't been serviced for years when we turned up to run the place 5 years ago.
Since left, (with tractor ) so don't have to worry about the neglect anymore.