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Don't do it

Thorsenator said:
Anyone have the K&N Filter system? Is it worth the $$'s?
K&N style filters (oil/gauze) do nothing for low end performance and have been proven to filter poorly compared to a paper filter from my dirt bike experience. They do increase flow at top end but also allow more particulate through. Personally I would not purchase a used truck or motorcycle that had a K&N style filter used in it.
 

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I would respectfully disagree. I have used K&N's both drop-in and cone type for many, many years. There is at least one thread on the subject here and several over at titantalk.com. No need to reinvent the wheel, but I can provide some brief specifics. Just for instance, my heavily modded CJ-5 Jeep runs a K&N pancake type filter sitting atop its carburetor. It runs a lot in the dirt, dust and mud. The filter went on the engine almost FIFTEEN YEARS AGO! and has not had to be replaced, nor has the engine been into since it was built at that time. This rig gets really muddy. The engine just keeps on going. Oil pressure, compression etc. remain normal. It does not use oil. That filter flows better when caked with mud and dirt than any paper filter will. Yes, I do clean and oil the filter ever couple years.

My Armada got a K&N drop-in the first month after I purchased it. The Armada replaced a '97 4x4 Expedition I bought new, and which also got a drop-in K&N within about a month of purchase. The Expedition had 107,000 miles on it when I sold it after seven years of daily driving, hunting, fishing, and towing a boat and a farm tractor. Compression was same as new, used no oil, oil pressure normal, never had a problem with that engine either.

BTW, while paper may filter better, there comes a point when better does not translate into longer engine life. The key is regular engine oil changes (3,000 miles - or less if you run in the dirt a lot), and of course, use a high quality filter.

I agree that unless you substantially increase flow on the exhaust side, you are not going to gain any significant power with a change to an oil gauze filter. I use them because I do like to run in the dirt and mud, and because you can buy one and use it forever. With normal use in city and highway driving, you only have to clean and reoil every 50,000 miles.
 

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A word of warning, if not installed properly the oil will fry your MAF sensor. I was thinking about going this route but after talking with a tech at the dealership decided the gains wouldn't out weigh the chance for possible warranty problems later. The tech said that they had had a few come through where they could see oil in the airbox and all they did was take a picture and send it to Nissan for proof.

Also there was a thread a while back on the snorkle for volant's airbox and a question about it sucking in water. The tech told me about a car that had the snorkle mouted down low and they were going down the freeway and locked up the engine in a heavy rainstorm. He said that there is in fact a low vacuum on the snorkle so it is possible to suck water in. Which is what happened in the case he was telling me about.
 

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I wonder what is meant by "installed properly"? If you are using the factory air box, you will note that the air comes in from the bottom of the filter and goes UP through the filter and then out to the intake tube where it encounters the MAF sensor on its way to the intake manifold.

There are probably some other engines where the design would allow any excess oil from an over-oiled K&N or other cotton gauze filter to drip down onto the sensor. It can't do that on our trucks. Gravity is working in the opposite direction, away from the sensor.

Another point to consider: There is no "install" to do with a drop-in cotton gauze filter other than to put it in place of the paper one. These filters come pre-oiled and need nothing done to them until the 50,000 mile mark. At that point, I fully agree that the user must use a cleaning and oiling kit , use it properly and not over oil the filter.

Although I have not tried or had a reason to do so, on our engines or on any personal vehicle, most MAF sensors can be cleaned by spraying a little denatured alcohol, letting it and the contaminant drip off and air dry. Older design engines sometimes had MAF's located after the exhaust gas recirculation system and would get fouled that way just through natural use. Denatured alcohol spray did the cleaning trick very easily.
 

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Not for me

Armada, granted you have had good luck with aftermarket filters and like them. The bottom line for me is they simply do not filter as well as OEM filters. Regardless of how much you change your oil, the first thing the extra grit sees is the valve guides and seats as well as the cylinder wall and piston rings during the intake stroke. Frequent oil changes will not help this situation out. You have gotten good engine longevity from your trucks using oil/gauze type filters; I can’t help to think that it could be even better with less dirt getting inside. I have read a test where you can see for yourself by putting a light coat of white grease on the intake tube between the air filter and throttle body and compare how much grit is stuck to the grease. The posted results of his test were a night and day difference between oil/gauze filters and OEM/paper type. In any case, to each his own
 

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Armada said:
I wonder what is meant by "installed properly"? If you are using the factory air box, you will note that the air comes in from the bottom of the filter and goes UP through the filter and then out to the intake tube where it encounters the MAF sensor on its way to the intake manifold.

Just repeating what I've heard in terms of the oil/MAF. I believe it was refering to the oiling of the filter.
 

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Healthy and robust debate of controversial subjects is good! I respect the opinions here. Indeed, each to his own, and this is one of those controversies where there may not really be a totally "right" and totally "wrong" answer.

For what it is worth, our company is a production remanufacturing, engine rebuilding company. We are not a big operation, but turn out about 1500 engines per year. We also operate a custom machine shop, for "special" clients, typically race engine builders who spec the machine work and sub it out to us to do. The customer does not really know who is producing the indexed cranks, decked and line bored blocks, etc. My dad founded the company in '47. I'm 54 years old, so we've been around for a little while.

We warranty our remanufactured assemblies. We have never had one come back damaged from the use of a cotton gauze air filter. What we do see is oil related failures for failure to change oil frequently enough and heat related failures for running the engine hot after a hose bursts or a radiator leak, water pump failure or other cooling system malfunction.

You can do oil analysis on oil at 3,000 miles and indeed, there will be a higher silicon content in the oil of engines that have been running the oiled gauze filters. But we just don't see any reduction in engine life.

Now racing engines are another thing. I can explain the difference between the advantages or disadvantages of endurance racing with the various types if anyone is interested. I believe the Titan that finished second in the Baja 1000 last November was running a K&N with an outside cover over it.

BTW, in addition to the shop work we sell hard engine parts, but don't sell filters or oil, so I don't have an economic interest in the issue.
 
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