Air Filters From Another Prospective

[The Dummy]

There is a lot of discussion on this and other forums about the worth of life time air filters when compared to OEM air filters. Most of the time the discussion is about which type filter allows the engine to breath the best while offering the most protection from mini particles of dust. It is a general given that the better an engine breathes the better the performance will be and the better the air filter deters the mini particles of dust, the longer the engine will last. It is, also, generally a given that the best performance of an engine's potential cannot be obtained while at the same time using a filter tight enough to give maximum protection from these mini dust particles. Hence, many contend that the better breathing life time filter, down stream of which some have witnessed dust in the airway when using them, must be detrimental to an engine's longevity because that dust must be harmful to the engine. This is a very rational contention and makes a lot of sense even to a dummy like me.

However, this is what I want to see discussed. I want to see if it can be determined at just what point does dust down stream from the air filter causes real damage to an engine. Dust in this case should be described as something not having a grainy feel to it when touched by a hand.

FWIW, it is my practice to filter my intake air with life time type filters. The results have been good. My interest in this subject is based on over fifty years of driving, riding, using, and working a variety of vehicles that at times for whatever reason did not have the intake air properly filtered and some of those times not filtered at all. Nothing bad of which I am aware resulted from these times of neglect. I hope that some of the members here share my interest and will offer their comments.

George

 

[TheLoneRanger]

Good observation George. Remember when cars had those 'oil bath' air filters? They were designed so the airflow would reverse 180*, and the heavy particles would be trapped in the oil at the bottom of the filter. I'm sure a lot of stuff got by those puppies.

I think most of the dust that gets by an air filter goes on through the engine and out the exhaust pipe. A lot of it is burned by the combustion process. What little that does get by the rings and into the crankcase oil, are particles too small to do any damage anyway.

I think regular oil changes are much more important than the type of air filter used.

But it's fun to discuss them anyway.....

TLR

 

[jmacmaster]

An above post states:

"I think most of the dust that gets by an air filter goes on through the engine and out the exhaust pipe. A lot of it is burned by the combustion process. What little that does get by the rings and into the crankcase oil, are particles too small to do any damage anyway."

For a long time I wondered if dust is combusted, that is burned up, in the cylinders with the gas. I was interested in the question because of the K&N air filter dispute. So I did a LOT of internet research on the question a few months ago. The answer is that dust does not burn up in the cylinders along with the combusted gas, unless the dust comes from something that is itself combustible. For example, wood dust would burn up in the cylinders, and so would dust that comes from grains such as wheat. But plain old ordinary dust that comes from dirt, gravel, and other things that will not themselves burn, is not combusted in the cylinders. And of course most of the dust entering an air filter is dust that comes from dirt and other things that are not themselves combustible.

Its often said that a good test of whether a K&N stops fine dust is to check out the intake tube upstream of the air filter. If you see dust on the inside of the tube, or wipe the inside of the tube with your finger and see dust on the finger, obviously, fine dust is getting buy the K&N. I run a K&N on an 03 Ford Ranger and an 03 Subaru Forester. I've performed this test on both without seeing any dust on the inside of the tube or on my finger.

 

[The Dummy]

TheLoneRange, these are my thoughts.

I am currently experimenting with an improvised filter using only a double layer of panty hose as the filtering media. When I get enough mileage with or without contamination, I will post the results.

 

[Blake Sobiloff]

Dirt (primarily silicon and phosphorous) making it past the air filter and into the intake system acts like an abrasive, erroding the intake valvetrain and the upper cylinder. The dirt does not get burned up, but either exits via the exhaust or makes it past the rings and into the engine oil. When in the oil it shows up in UOAs AND it also acts as an abrasive throughout the engine.

The way to differentiate between silicon from engine casting and seals, and silicon from the intake, is to look for elevated wear metals that are common in valve trains and rings in addition to elevated Si and Ph. You'll often see elevated Fe when there is elevated Si/Ph as well, showing the abrasive nature of the Si/Ph throughout the engine.

I believe Terry's opinion is that air filtration is vastly more important than oil filtration for the life of the engine.

I ditched my K&N air filter shortly after joining this board and reading about the frequent (but not always) increased contamination levels. In my first UOA for my truck I had elevated levels of dirt and corresponding wear metals. I will soon do my second UOA on my truck after having switched to the OEM paper filter and hope to see the levels start dropping.

 

[RichD]

Blake,

That was an amazingly coherent and well thought out post, thanks for sharing.

Regards,

Rich

 

[vad]

"Air filtration is vastly more important than oil filtration for the life of the engine."

 

[Blake Sobiloff]

Thanks, guys, but there's no original thoughts in that post--I stand on the shoulders of giants.

 

[GatorJ]

quote:

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Originally posted by Blake Sobiloff:
Dirt (primarily silicon and phosphorous) making it past the air filter and into the intake system acts like an abrasive, erroding the intake valvetrain and the upper cylinder. The dirt does not get burned up, but either exits via the exhaust or makes it past the rings and into the engine oil. When in the oil it shows up in UOAs AND it also acts as an abrasive throughout the engine.

The way to differentiate between silicon from engine casting and seals, and silicon from the intake, is to look for elevated wear metals that are common in valve trains and rings in addition to elevated Si and Ph. You'll often see elevated Fe when there is elevated Si/Ph as well, showing the abrasive nature of the Si/Ph throughout the engine.

I believe Terry's opinion is that air filtration is vastly more important than oil filtration for the life of the engine.

I ditched my K&N air filter shortly after joining this board and reading about the frequent (but not always) increased contamination levels. In my first UOA for my truck I had elevated levels of dirt and corresponding wear metals. I will soon do my second UOA on my truck after having switched to the OEM paper filter and hope to see the levels start dropping.

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It is interesting you mention Terry in this post as a justification for not using K&N air folters. He does (or at least did.). http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=15;t=000052#000008

[ March 18, 2006, 09:59 AM: Message edited by: GatorJ ]

 

[GatorJ]

"filters"....sorry.

 

[Blake Sobiloff]

GatorJ, I did not use Terry as a justification for not using K&N (or any other) lifetime air filter. I said that Terry seems to believe that air filtration is more important that oil filtration for the life of the engine. If you are able to get good filtration from a K&N, more power to you. (No pun intended!)

However, peoples' success with K&N (and similar) air filters seems to vary considerably by vehicle application and the owner's skill in properly cleaning and re-oiling a K&N. In my truck's case, with a brand new K&N (pre-oiled) I was seeing high dirt ingress in my UOA. I have switched to an OEM paper filter to see if the K&N is the culprit or not.

 

[The Dummy]

Please, allow me to guide us back to the point of my original post. I don't question that fine stuff contamination passes through some if not at one time or another all air filters into the air way between the filter and the engine and then, into the engine itself, nor that when it happens, it will be discovered by a UOA. However, that is not the point of my post. My question is:

I want to see if it can be determined at just what point does dust down stream from the air filter cause real damage to an engine.

Without much question, should no filter be used and a June bug or a beetle or dragon fly be sucked into the an intake there will problably be damage....or would there? How about the fine stuff? Whether it dissaptes in the cylinder or is passed via the exhaust with out having disapated, what internal damage will been done by its passing through in the first place. My experience tells me that a lot of performance is lost by any kind of commercial air filter, be it OEM or long life. I am attempting to discover that if filtering only to the point of stopping large stuff is all that is done, is there a point where damage to an engine occurs and if so, where is that point?

Thanks for keeping the post active.

George

 

[Blake Sobiloff]

George, the damage is gradual from increased wear. The amount of wear is linearly related to the amount and composition of the dirt ingested. There is no "single point" at which damaged is caused.

 

[The Dummy]

Blake, I agree.

Dirt ingested, I believe is a key to wear. Ingested where, though? Into the cylinder and passed out through the exhaust or ingested into the innerds via blow by where it can be carried and distributed though out by the lubricating oil circulation? I would think that fine stuff sucked into and passed out of a combustion chamber would do little harm. The same distributed through out an engine via blow by may or may not be a major thing and there in is where my questions lie.

Reason, all but demands one to believe that any contamination anywhere is detrimental to an engine's wear. I can accept that this is true but is there a point were concern about the size and/or the amount of the contamination becomes impractical? Maybe, when it is small or fine enough? Is that even possible?

I can say that I have experienced situations where little on no air filtering was done and no obvious damage occurred. Based on those experiences, it just seems to me that the industry's and general public's thoughts on the air filters of today may entail substantial over kill that is financed by the lost of both performance and economy.

 

[TheLoneRanger]

George, my opinion is that most 'debris' that an engine ingests is pollen, cellulose, rubber particles, carbon, etc. that's not harmful anyway (too soft).

The hard silicon particles that pass through a filter would have to be larger than the hydrodynamic oil film between the rings and rod/main bearings to cause wear. I'd say anything under 15-20 microns is harmless, and any filter should pass that standard at the very least.

My point is, it's not the amount of SI particles found in oil analysis that's important, it's the SIZE of the particles.....

 

[The Dummy]

Ranger, that makes sense to me.

I have searched the posts in this forum and have not found any that tie SI particles directly to damage. At my rate of scanning posts, I may have overlooked some though.

I did find some numbers related to indoor dust by someone hawking indoor air filters. This says that approximately 98-99% of all particles by count are in the size range of five microns or less. Being an indoor application, wind and turbulence created by passing vehicles do not contribute to the air born particles in their analysis. It may be safe to assume that anything larger than five microns will settle to the ground. It may also be safe to assume that many particles caught in wind and turbulence have a chance enter an intake before that settling takes place.

As mentioned above, I have devised a filter that consists only of a double layer of panty hose. I have used this for a short week and find no visible contamination in the intake either by touch or sight. I will continue to observe and will post the results as time passes.

 

[BigV]

Good thread.

Last year when Mt. St. Helens was doing some spewing the local talking heads gave some car warnings. One of the things they stated was that the only air filter that would keep the ash out of the engine was an oil bath type!

Like anything else on TV I don't know if it can be believed. I know that ash is very fine and contains a very high amount of glass. I know from experience that the glass will bond to everything in the combustion chamber.

My uncle still has a cylinder head hanging on the wall from the 1980 eruption. The combustion chamber and valves all have a glass coating bonded to the metal.

Obviously this is a worst case extreme condition thing.

I am however wondering if anyone would know why they would say an oil bath is the only air filter that would stop the ash.

 

[Jan Richter]

quote:

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I am however wondering if anyone would know why they would say an oil bath is the only air filter that would stop the ash.

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I would guess that they thought the ash would be "caught" when it passes through the oil. Many people think that the incoming air bubbles through the oil bath.

The incoming air actually just passes through the oily mesh. The mesh draws oil up, through capillary action, from the oil bath below. Just as a vertical stranded wire will draw molten solder up, seemingly defying gravity.

Do you remember those oil bath filters? The mesh was so coarse you could read a book through them.

Jan Richter

 

[snoboy]

quote:

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However, peoples' success with K&N (and similar) air filters seems to vary considerably by vehicle application and the owner's skill in properly cleaning and re-oiling a K&N. In my truck's case, with a brand new K&N (pre-oiled) I was seeing high dirt ingress in my UOA. I have switched to an OEM paper filter to see if the K&N is the culprit or not.

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Very well said Blake. I was 1/2 a step away from putting my stock air cleaner back on the PSD today, but then I thought... Terry says my airfiltration (Airaid w/ nylon prefilter)is working good on this vehicle so I better leave well enough alone. My two gas rigs on the other hand have both been converted back to AC Delco paper OEM fit panels to try and squeeze out every ounce of clean air that I can.
I agree it is per vehicle and conditions each vehicle is used in as to air filtration.

snoboy