Thread: K & N FILTERS

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

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 .....

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 .....

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.