Into: I am a first time Jeep (2dr JK 08 Rubicon) owner and long time lurker.

I am looking to use my JK in the Southwest desert (Utah) extensively. I am looking for an air filter that works significantly better than the stock filter for removing very fine particles.

On my dirt bikes (currently a KX500 and TT500) I have tried Gauze type filters (K+N) and have found that a significant amount of fine dust can be found in the intake of the carb in a short period of time (200 to 300 miles). I have used a K+N filter with a “Pre Filter” (K+N) and have found that it helps but does not fix the problem. I now use Twin Air foam filters exclusively and have found that they stop fine dirt 100%. I have had the KX500 on a dyno with both the K+N and Twin Air foam filter had have essentially the same power and power curve. The K+N with the pre filter did show a slight loss of power across the range. I have Dyno’d both with clean filters and with 500 miles of heavy use. The down side to foam is that it can clog up faster (I carry a spare just in case) but have found that if they are serviced every 800 to 1000 miles I have never had a problem. Both filters were sealed with heavy grease at the mounting points. The condition that these foams filters work in is that the dust is so thick it can look like fog at times. I have never had a foam filter clog up and as long as I clean it every 800 to 1000 miles and it never has impaired bike performance. When you clean the filter it is amazing the amount of dirt lying in the bottom of the cleaning bucket.

I have looked at all of the fabric type filters (Dry and Wet) and do not see any significant differences in air cleaning ability. I am currently looking at the www.trueflow.com/xdi.php. I am not looking for MPG or HP I am looking at keeping the Engine alive. Looking forward to comments especially you dessert guys. They Trueflow people have some interesting propaganda including a video that is worth the time to peruse. I will not be fording any water of significance so I am not worried about that.

Quick Comment: Great Resource for Information

Misc. Comment: I have just installed the Shock Works Stub Bumper, Rock Rails. Very very well thought out and constructed. My only negative comment is the pictures in the directions are too dark. I also installed Warn Power Plant Winch with Syn rope to top it off.

Stuff to Go: Oil pan protection (either Hard Rock or Skid Row) and Diff protection probably Great Lakes Off Road.

 

I personally have the AEM but I am nowhere near the desert. After doing some looking around you can get the XDI from 4wd. I believe it is the first (and only so far?) foam intake for the JK. It is a little more expensive than the other CAIs. Good luck and show pics if you wind up getting the XDI.

 

just a thought; in some parts of the world vehicles are fitted with a snorkle to get the air intake farther away from the ground. Generally speaking, the closer to the ground, the greater the mass of suspended particles. Plus which, it looks extremely cool.

A pre-separator, such as a cyclone-type device as is used on heavy equipment, can also help keep your final filter from being overwhelmed. I have seen these somewhere for mid-sized trucks used for construction. they tend to be large, though.

Also, I used to run a coarse foam pre-filter on a paper filter on my work trucks for the same reason. I suspect that an oil bath filter would work better, since they mainly catch big stuff but don't load up quickly and are easy to service.

You really want to catch the particles with a size approaching the oil film thickness; smaller stuff will end up in your oil or go right on through, but the big stuff will do damage, and loads up your filter. That's where a centrifugal separator, impact separator, coarse oil bath, or similar, will pay dividends. It'll get the big stuff and help keep the real filter from loading up quickly. Even a baffle in the intake would probably help some.

I doubt that any of the so-called "performance" or "CAI" (and none of them are really cold) intakes will offer filtration approaching even the OEM; they generally create more noise and no performance boost. But you've already figured that out.

 

I've used foam styles in the past on other vehicles and it seems that they're numbers are always greater than K&N or dry filters. They seem to do a good job of filtering as well. However, they do need to be replaced more frequently than other styles and they get very nasty if not replaced and begin to brake down and crumble. Not a fair, personally, but if you can keep up with the maintenance then it's up to you.

 

thought this looked like an interesting thread, so I went and did a little digging. I didn't find any sub 1 micron filters, but found the following that may be of interest for guys looking to keep water out of their air intake.

INJEN HYDROSHIELD PRE_FILTER

Gotta wonder if $25 wouldn't have saved one of those hydro-locked JK's

Pre-filter description:

Injen Technology's Hydro Shield pre-filters feature race-proven material manufactured from highly durable polyester. Their uniform micron openings allow the filtering of debris .005 in. or larger. Injen Hydro Shield pre-filters are factory-treated using an embedded hydrophobic process, which offers consistent airflow, repels water, and maintains horsepower gains.

 

K&N also has a hydrophobic wrap for their filters; you'll see them especially on the bent noodle HD filters. In my experience they keep rain out, but not much more than that. They're basically a piece of Gore-tex, I believe; plastic with holes too small to pass water drops.

Got any ideas on pre-filters?