Filters get more efficient with more miles?

[Patman]

I thought this would be a good topic, do you guys agree that as an oil filter captures more
dirt, that it becomes more efficient? So if a new filter traps 99% of particles 15 microns and
bigger, then after 5k that number could be 99% of particles 10 microns and bigger?

Although then the flow rate would also start decreasing too.

The tech rep at AC Delco didn't agree with me on this theory, however he didn't give
a reason why.

 

[jjbula]

Without much knowledge of bypass settings
I would be worried about the filter going
to bypass more often.

I did read at the SHO site that filters
don't even come close to capacity for the
average car. (1/4 of capacity at change)
If that is the case I would say no to better
filtration over time.

Just my unprofessional opinion, I mean hunch.

 

[Patman]

I suppose in the case of my car, I'd probably never see the filter get anywhere close to capacity, the filter my car uses is huge! I use the longer than stock one, which is the PF35 AC Delco right now (but soon to be switching to the L30040 Purolator)

 

[widman]

I've read several studies that confirm this. A lot also has to do with the oil's ability to absorb soot and sludge without clogging, so different oils have different effects.

 

[VaderSS]

This is VERY theoretical, with only my common sense for backing it up, but it seems like; as larger particles cover holes, smaller holes would form and the filtration of the smaller particles would increase, much the way a K&N filter becomes more effecient as it forms a layer of dust on the surface of the filter.

 

[Patman]

That's the way I figured it would work as well. This is why I tell my friends with K&N air filters
not to clean them too often. Especially since they end up either overoiling (which is bad for
the MAF in a lot of cases) or underoiling. I know one guy who oiled both sides of his
filter!! Any time I've owned a car with a K&N filter, I've let it stay dirty and haven't cleaned it
( I don't usually hang onto cars long enough to reach high mileage on them anyways)

 

[VaderSS]

I'm the same way. I leave it in for 50k miles, like it says. Then I follow the cleaning instructions to the letter. I talke to a diesel mechanic. I coold not make him believe that he was shortening the life of his truck's engine by blowing his K&N out every month with compressed air.

 

[C Willi 01SS]

Doesn't more efficient filtration = *restrictive*? Maybe over a period of time a typical K&N air filter would become just like any other paper filter as far as flow is concerned, this is a good topic. Exactly why I haven't put my Holley Powershot on my LS1 SS Camaro yet, I just don't know if the increased flow is worth the additional particulate and the additional 1~2 hp.
Gotta love this board!

 

[widman]

I guess we jumped to air filters. The typical mechanic here believes you should use compressed air at 120 psi to blow the dirt out of your filter after every trip or minimum of weekly. A friend of mine (Agronomist) bought a Cherokee and his neighbor the mechanic said he'd do him a favor and clean the air filter after every trip to the country (3 times a week). After 2 months he had to rebuild the engine. I just replace the filter every 12,000 miles or when I loose power from clogging on the throw aways. I have two with cleanable outer filters and oil impregnated wool inner filters (only 5% of our roads are paved).

 

[C Willi 01SS]

DANG.....Just swithced channels as soon as I posted that last post and on *popular hot rodding tv* is a special on performance oil impregnated air filters!!! An '02 Saleen Mustang is on right now.

 

[VaderSS]

quote:

---

Doesn't more efficient filtration = *restrictive*? Maybe over a period of time a typical K&N air filter would become just like any other paper filter as far as flow is concerned, this is a good topic. Exactly why I haven't put my Holley Powershot on my LS1 SS Camaro yet, I just don't know if the increased flow is worth the additional particulate and the additional 1~2 hp.

---

Usually more effecient does equal more restrictive, but a new K&N will flow about 50% more than a clean paper filter, while achieving comparable effeciency.

The nice thing is, as it gets dirtier, it filters even better and when the filter has reached the 1/2 way point in restriction, where it is recomended to be cleaned, it is flowing only slightly less than a clean paper filter, but will have gone twice as far to reach that point.

[ July 29, 2002, 04:01 PM: Message edited by: VaderSS ]

 

[GROUCHO MARX]

Could K & N just sell pre-dirtied filters?

 

[Kevin in Texas]

Yes, as particles become trapped on the filter media, they will build up a layer that will actually filter out smaller particles.

I know this for a fact due to the industry that I am in. I am a plant chemical engineer and we have many (>30) different types of filters. In some powder systems we actually feed a filter-aid that helps build up a cake layer right after installing new media.

Patman:
While your thought process is correct, it only works up to the point in which the pressure drop across both the particle layer and the filter media gets to the point that the bypass valve starts to open. The biggest problem is knowing when that point is. In todays times, I don't know why OEM's could not install both an upstream and downstream pressure sensor and feed it back to the computer to let you know when your filter is about to go into bypass.

 

[BOBISTHEOILGUY]

Problem is filters are in by mode when cold and first started, therefore would set alarm off. It would have to be programed to work only after the cold start program loop has been opened then read the sensors.

 

[Bluestream]

Looking for more info on this topic

 

[jhellwig]

While it is true that a filter gets more efficient once it has caught more dirt, the restriction goes up a lot more to the point it is detrimental to flow. It happens so quick that the damage will be done by the time you notice it.

 

[Bluestream]

What kind of Damage are you talking about?

 

[jhellwig]

Originally Posted By: Bluestream
What kind of Damage are you talking about?


Once it gets to bypass all the time you will have unfiltered oil and if anything happens to come loose there will be nothing to catch it.

People used to use this theory on fuel filters on diesel engines. It wasn't much of a problem on older engines but new ones don't like it at all and it will cause damage to injectors.

If you graphed flow verses restriction it wouldn't be a linear line. It is a square root function.

 

[4WD]

This is similar to DE filter concept use on pools, wine etc. However, my pool filter has a pressure gauge right on the can ...
Suppose with a four port remote filter mount you could read it directly - but I have too many vehicles not showing oil pressure at all - so no record runs for me.

 

[Bluestream]

A filter would have to be totally plugged to go to by-pass. I have never seen one like that. The most I have done was 20,000KM on one filter on my daughters Cavalier that was a Purolater/Mann ML1000. It looked fine.