\ K&N Air Filter Pre-Charger

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Let it Breath!

Home Made K&N Pre-Charger

October 2000 - I noticed that when I would pull the filter off to clean it, I found just a bit of very fine dust inside of the air tube.  Obviously, the K&N filter is not taking all of the dust out of the air.  I searched at several parts stores and the local 4x4 shop I frequent.  No one had a K&N pre-charger.  (several didn't know even know what it was.)  So, I opted to try my own pre-charger and see if it makes a difference.

I stopped by the Home Depot store and picked up some 25 gallon wet/dry vac paper filters.  After cleaning the film of dust in the air tube, I put everything back together and slipped the paper filter over the K&N filter.  The filters came with a big rubber band which worked just fine in holding the filter in place.  I'll post my findings in a few months and let you know how it turns out.  With luck, it will eliminate the very light film of very fine dust that was in the air tube.

Here are a couple of pics of my pre-charger.



December 9, 2000 - So far, so good.  I ran a mileage check the other day when coming back from a wheelin' trip near Tucson.  Doing 60 MPH on the highway, I averaged a bit over 19 MPG.  I am still running the first filter bag.  It is starting to get dirty but the mileage check indicates I am not starving for air, so I am not going to change it for a while.


December 28, 2000 - Today was maintenance day on the TJ, oil change, grease job, etc.  I decided to pull down the air filter setup and see if my pre-charger has been keeping that ultra-fine dust out of the air tube that I noticed back in October.  After I got the oil and lube chores taken care of, I removed the filter and the air tube.


The bag looks like it has seen better days, but it is just dirty.  The rubber band that came with the bags is still holding the bag securely onto the outside of the K&N filter.  I am sure I could have let it go longer (based on the mileage check from earlier in the month), but I really want to see what the air tube looked like on the inside.  The last month's worth of trails that I had run were all nice and dry so we had the typical dust that I was seeing during the summer runs.


Here is the new bag that will be going on the filter.  A side by side comparison gives you a better idea of just how much dirt was trapped by my $.50 pre-charger (or maybe it was less than that).  But....the real question still lies in the air tube.  Will it have that same fine coating of dust like I found back in October, or will it be clean?


Well, here is the answer.  Clean as a whistle it is!  This is the end of the air tube that is clamped into the K&N filter.  There was no dust inside the tube!  In October, this was cleaned out.  So that I would have a reference to compare it to, I did NOT clean out the section of the air tube that connects to this part and goes all the way to the throttle body.  I removed that part (the stock factory tube) and checked it.  It still had the fine little coating of dust.  I then washed it out with some soapy water since my experiment is now done!

The K&N filter had a little bit of dust in a couple of areas.  One of these is where the paper pre-charger rubbed against a wire loom enough to make a small hole in it.  This would make sense since the K&N didn't have the full effect of the paper filter. 

So....as I had discussed with the old off-roader....you don't run a K&N filter in a dusty environment without using a pre-charger.  I can handle that.  Shop vac paper filters are cheap and easy and disposable too!  I am guessing I'll use about two per year....yeah, I think the Jeep budget can handle the extra dollar!

More K&N filter



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