Thread: opinion vs empirical fact -air filters

that's quite interesting!

but what does it all mean?


when i order a filter for lurch...i just take what im given....i dont think i have a choice in brands....im lucky to find one that fits...

someone on the AULRO mailing list was advocating oiled cotton filters a while back, I disagreed and reffered to that test and was howled down and told It and I were biased !
This after me admitting to using K&N back in my racing days after dynoing them for outright power and torque on Formula Fords. (better than PiperCross and UniFilter, and when slightly 'altered' better than no air cleaner at all !)

I pulled the one off the 'fender two years ago after my suspicions had been raised. (anyone want to buy a K&N for a 300Tdi ?, only used for 25 000km :wink: )

That test, when first posted on the 'net six months ago only confirmed what a few had already suspected.
Great for airflow and going fast. Not so good for outright filtration in a dusty environment.

I had the same experience. I had a K&N on my 3.9.
Firstly the MAF was coated with oil , then I went on a dusty trip to Yerranderie ,and could see visible dust on the MAF on return.

I have always swallowed the hype on aftermarket filters, but never again.

One point is that any gains are also are only at max load max revs. How many times do you use that other than racing. The ISO test was done at 350CFM and a 3.9 and other Rovers would not get to 350 CFM. We do not know the size of the tested filters of course. 6.5 inches of water for the OEM filter is very little by the way. My snorkel has 8 inches at max load/revs before the filter , which is still very little resistance..
Reagrds Philip A

I forgot to add that I reduced silicon levels in my oil analysis (silicon is a dust indicator) when I went back to using a Donaldson element. The Si levels were OK with the K&N, but were significantly better with the paper element.