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I have provided my opinion supported by sound evidence.
Writing text of your opinion on an internet forum is not evidence, the ONLY thing you have provided is an unsubstantiated anecdote.
You have not provided any evidence of testing. You have not provided any data to be reviewed. You have not linked to any studies. You have not done anything but talk about your personal subjective opinion about how your vehicle "feels" to you.
I doublt you actually understand what the words "objective" and "evidence" actually mean in science.
I have had 2 Peugeot 504's ( 1979 & 1980 ) cars which had oiled foam air cleaners. I washed them out & re-oiled every 15,000 km in country conditions. They always looked quiet dirty on the inside (catching side) & clean on the carby side. The 1979 car did 450,000 km before being retired . The engine compression figures were still very acceptable & even. The car had never had the head removed. I still have the 1980 vehicle & the oiled foam filters have been used for 36 years without any detrimental effect.
In latter years instead of mineral engine oil I have used the motorcycle sticky/drying type which seems to be effective.
My 1984 Honda farm motor cycle also lasted until this year with a oiled foam filter covering a cloth type in a frame. . Its compression was down but still started easily. It served in dusty off road conditions.
I have had trusty lawnmowers with oiled foam filters which lasted many many years. The steel frame rusted before the engine failed.
Our later vehicles ( 405 Peugeot Diesel & 204 MB Diesel) & lawnmowers were fitted with paper filters & again I have had no complaint with them.
So my advice in this discussion is what ever form of filter you use , so long as they are cleaned regularly or replaced at the makers recommended interval all will be well.
P.S. My first car ,a 1951 Wolseley 6-80 had an oil bath air cleaner which consisted of a wire gauze cage in an oil bath. All the rings were broken & in the sump but cannot say whether the cause was dust or not. !!
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Originally Posted by Carsy
That is interesting. JC
Oiled foam filters also suffer greater differential across the media but are not used in applications where you are trying to extract the highest volumetric efficiency out of the engine.
Thats because foam filters are a kind of "labyrinth" filter. They rely on the air having to frequently change direction which causes dirt to lose velocity and fall out of the flow.
K&N relies entirely on the low surface tension of the oil to capture dirt as it contacts the oil. Problem is, there are very large holes in the mesh of oiled gauze filters and the momentum of the dirt can cause it to not stick at all or be pulled out of the oil.
Those large holes are the entire problem. They are what give K&N great air flow, but they don't filter worth a crap and they plug up extremely fast.
Air filter designs are a balance of restriction to flow, filtration quality and size (surface area). ALL filters will have measurable restriction unless its very oversized or very poor filtering. The question is, is that extra 5hp at the very top of the RPM range that you use only a small amount of time really worth allowing more dirt into your engine all of the time?
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Originally Posted by OM617.95
Thats because foam filters are a kind of "labyrinth" filter. They rely on the air having to frequently change direction which causes dirt to lose velocity and fall out of the flow.
K&N relies entirely on the low surface tension of the oil to capture dirt as it contacts the oil. Problem is, there are very large holes in the mesh of oiled gauze filters and the momentum of the dirt can cause it to not stick at all or be pulled out of the oil.
Those large holes are the entire problem. They are what give K&N great air flow, but they don't filter worth a crap and they plug up extremely fast.
Air filter designs are a balance of restriction to flow, filtration quality and size (surface area). ALL filters will have measurable restriction unless its very oversized or very poor filtering. The question is, is that extra 5hp at the very top of the RPM range that you use only a small amount of time really worth allowing more dirt into your engine all of the time?
Absolutely. K&N oiled screen filters are nut & bolt catchers. The difference between their nominal & absolute filtration capability is huge at 75 Beta ratio. A really good filter might only have a spread of 3 microns between nominal & absolute rating.
04-14-2016, 04:53 PM
