Hey Guys,
I've seen some of you have modified your stock air boxes? I would like to know how you did it? or if you have pictures and did you notice any added benefits from modifing it. Thanks

 

I am waiting for the K&N FIPK 2000 CARB certification. In the meantime, I have replaced the air filter box extension tube with 3" thin wall landscaping PVC. The OEM extension is 2" in the fender. I noticed high rpm, WOT performance was improved. It cost $5. This type of PVC fits snug in the air filter box without modification, and when squeezed slightly also fits right through the fender hole without modification .

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2000 F-150 XL,RC,LB,5.4,4R70W,3.55LS,
Class III tow/Payload #3/Convenience pkgs.,
4-wheel disc/ABS,Chestnut/Parchment 40/60,
Ford bedliner & gas/wheel/spare locks,
3" cold air box modification, Superchip,
Dynomax ultra-flow welded 3" cat-back,
3" exit Y-pipe, Hellwig rear anti-sway bar.

 

Hello Horseman,
I have a 97 F150 regular cab w/ V6. I bought the drop in K&N cone filter and took the air filter cylinder shaped box off and then cut the base off. That allowed me to use that base as a retaining ring to hold the drop in K&N to the intake tubing. I then discarded the cut off piece of cylinder box and the rubber fender tubing. I have noticed quicker throttle response and a throatier engine, but as for gas mileage, I couldn't tell ya. I drive my truck hard and don't pay attention to mileage. Good Luck w/ your mods.

 

I have done two different scenarios myself, the first was to remove the air box (fenderside part) then if you will notice the K&N filter will fit on to the engine side and lock into place under the retainer that orignally locked the two halves of the air box together. Then if you notice under the the remaining half of the air box there are two tabs that stick out, and are close to the distance of the retaining holes that the removed part of the air box locked into (underneath) I enlarged these holes and pressed the tabs into it. I looks great and works very well.

I also have a modified air box. I took a dremel tool and cut out the top third of the box, this allows the cool air to come in from the fender, as well as more air flow, it also helps keep the hot exhaust air from the filter.

 

After reading this, I decided to pull the rubber piece out of the body...then I took the box apart, and cut it in half, so that it still holds the filter in place, and the "feet" hold it down so it doesn't flop around. Now it looks just like a real filter charger.

Did I help my engine by allowing it to breath better, or did I hurt it by allowing warmer air to be taken in?

-AR

 

i did the same thing to my truck and i did notice some improvement in the seat of the pants dept, but i also am now getting a lean code on the diagnostic. i'm not too worried about it though, i've got a hypertech module on the way that may take care of that.

 

This is mine before I sanded it down:



I did notice a little difference and the exhaust sounded a lot deeper compared to what it was before.

However if I were to do it again I woud only cut off the end and and make a 1" wide cut the length of the filter instead of cutting the whole top off.

Talley did some reasearch ont he subject and found that a paper filter with a 'power tube' and the stock overing left over the filter worked the best . The cover was modified, but it still pulled air out of the filter which brought the temp down inside of the filter chanber something like 10 degs. (if no more)