I just modified my factory airbox on my 2001 Expedition with the 5.4 so that I now have a cold air intake system that cost me $50 for the K&N filter and $3.75 for a piece of sheet metal. And WOW...what a difference. The great thing is, it is simple if I need to go back to stock for any reason.

 

BrandonJ:

I already have the K&N filter in the stock enclosure. This looks like a project that i will have to do or i won't be able to sleep at night.

Do you think that sheet metal from a furnace duct work will do? If you have any other tips or shortcuts to make this project even more user friendly, please post!

Will the life span of the filter be decreased because of the increased exposure to the elements? Will rain and snow find its way into the filter because of the open concept? We get alot of that here in michigan. Thanks.

-hooD



2002 F-150 4x4 REGULAR CAB
DARK SHADOW GRAY CLEARCOAT
XLT 139" WHEELBASE STYLESIDE
5.4L EFI V8
ELECTRONIC 4-SPD AUTO O/D
3.73 RATIO LIMITED SLIP AXLE
SKID PLATES
7700# PAYLOAD GROUP
TRAILER TOWING GROUP CLASS III
LT245/75R-16D OWL ALL-TERRAIN
1,175 MILES AND COUNTING

 

hooD

Any kind of sheet metal will do. I just went for the cheapest I could find. As long as it holds shape enough for the clamp to grab it, it will work. I would even have used black plastic if that had been available. I cut mine with a pair of Craftsman all purpose snips that had serrated blades. There are probably much better tools to use but again, cheap was the goal here so I wasn't going to buy something just for this purpose and never use again.

The only real tip may be for cutting the inside of the ring. First, gloves are a must unless you want to cut your hands all to heck. Second, drill a pretty good hole well inside of your cutting line so you can get your snips (or whatever tool you use) in easily. And last, don't be afraid to bend the metal even almost in half to make the cuts on the inside of the ring. It will flatten back out and it makes things much easier to cut.

To answer the life span question, no. First, it's basically the same filter that is used by K&N in there $225 FIPK, second, define "life span". It's a lifetime filter that you just wash when it get's dirty. If "life span" is the time between cleanings, I wouldn't expect to see much difference.

If you consider the stock air box with it's hose on the end, though it's smaller, it still has to suck in air (and whatever might be in the air). If moisture was really a problem, it would be with stock as well. If you relocated the filter to a more open place in search of cold air (like toward the bottom of the bumper) then yes there would be a posible problem. Just but a bag around it when cleaning your engine compartment at the car wash.

Post back with your feelings once your done.

BrandonJ

 

BrandonJ:

Well, i did it! Went to the local hardware store and bought a piece of galvanized "joist panning". It's used to make the cold air return system for a home furnace. It cost me $3.59

I made a template out of cardboard and traced that onto the sheet metal. Then i used my trusty Dremel with a cutting disc and cut the inner circle out first. My tin snips were used to cut the outside circle. They cut the metal like paper. The fit was perfect.

Using a large screw driver i was able to pry the airbox out of the rubber groumets. That was actually the hardest part. I drilled a hole between the rubber groumets as the instructions shown. The metal clamp has a tab on the bottom that fits perfectly into the drilled hole and it secures the filter system very nicely.

Being that i only have 1600 miles on my truck, and the fact that in stock form, with airbox and factory paper filter, this truck was already fast as heck. When i go to work later today i will see what changes i can notice. If nothing more, the MPG's might be a tad better.

Thanks for your tips and i will update with any gains that i notice. This was a very cheap project if you already have the K&N filter like i did. But now i know i will see the maxium benefits by having an open airbox.

-hood

 

Brandon, great idea and a great article. But can this really be considered a COLD air intake when it will now pull air from inside the engine compartment? Anyway, an excellent article.

 

Monsta...you are right. It's not truely a cold air intake since it isn't located where cold air can really get to it. The main thing is that it is basically a FIPK that is close enough to the AirRaid, K&N Gen2 FIPK, and the like for my money. I would bet money that you won't see enough difference between this mod and the $200-$250 kits to justify the difference in price.

I had thought about leaving the box on, taking off the tiny funnel hose from the end where it goes into the fender well, and then running some tubing down under the bumper. Then I thought, that's taking a big risk of sucking up moisture and other crap from the road and really wasn't worth it.

Brandon

 

Here what I did, was took a grinder to my air box cut where it holds the filter in until, I got to the bottom then I left the bottom in so it will set just where it was at. Should help water from the road getting on it too.

 

F15042624:

I thought about cutting my airbox too, but before i did, i called the Ford dealership and found out that they cost $255.00 for both halves of the airbox. If you ever need to go back to the original equipment it gets costly to replace the airbox. I decided to make the ring instead. The cost was only $3 and took about an hour to make.

Is a K&N air filter (E-0945) and a modified airbox worth it? My answer is yes. My 5.4 gets up and screams!

2002 F-150 4x4 REGULAR CAB
DARK SHADOW GRAY CLEARCOAT
XLT 139" WHEELBASE STYLESIDE
5.4L EFI V8
ELECTRONIC 4-SPD AUTO O/D
3.73 RATIO LIMITED SLIP AXLE
SKID PLATES
7700# PAYLOAD GROUP
TRAILER TOWING GROUP CLASS III
LT245/75R-16D OWL ALL-TERRAIN
BUILT FORD TOUGH!!!
1,965 miles

-hooD

 

Aww, that's no fun! You get a much higher shock-value from the wife when you head out to her vehicle with a saw!

I cut the airbox too. But, I left it long enough to use the "feet" that snap into the factory mounting bracket. I had previously fashioned a "ring" like the one in the instructions, but rough roads (and no roads) caused the filter to flop around too much when not using the strongest possible mounting system.

 

Great job Brandon. I was laboring over the idea of if the K&N FIPK was worth the money or not as their kit draws hot air from under the hood instead of fresh air (figured I could do that myself and save $150+. So I went was researching to see if anyone made a adaptor that would work as your artical described when I came across yours.

I was worried about how long it would last as well as how well the filter would be "protected" from water and debri kicked up from the road. I to was ready to cut my own air box but called the local dealer first (replacement cost is unreal)then went to the local "pick your own parts" I got an air bok from a crashed 98 EB for $25 and was able to modify it to accept a larger diameter "snorkel hose" that I conneted to a now enlarged hole in the inner fender well (3" dia).

Net result = seemingly much freer breathing, QUITE, REAL cold air filter kit. AS for more power? with over 5000 lbs 5-10 hp would be real hard to notice. As for MPG's, well with my heavy foot. . . I'll need to run a couple more tank through her to get a good average and let you know.

I'll see if I can get hold of a digital camera and share with you all

Petrol 99 XLT 5.4L

 

Great idea Petrol! What did you use for a snorkel? I assume you didn't make the hole in the fender larger...just took out the factory snorkel...right? I would love to see pictures if you get around to it.

BrandonJ

 

Whoa Brandon

AWESOME homemade FIPK. Great instructions on your web site also! I ordered up my K&N filter and should have it tomorrow. Cant wait to get started.

NoMo,
also a great concept the way you left the second half of the breatherbox intact to take advantage of the stronger mounting system. Im going to try just the ring alone first, but if that dont work, then ill cut my airbox as you did. Nice pics on your site by the way.

Question, after making the FIPK, what if you ran "ductwork" from lets say under the front bumper area to the filter? Not so it is in direct contact with the filter, but just into the general area of the K&N filter. Wouldnt the filter then suck in the cold air the homemade "ductwork" was supplying? Would this make it more of a cold air filter? Maybe if you ran it so it was pointing upward when it got near the filter it would lesson the chance of moitsure getting to the filter? Even could put a wire mesh screen on both ends of the ductwork. Granted, the filter would still be sucking in warm engine compartment air, but the air may be cooled down some by the ductwork, when rolling anyway. Also, was thinking of cutting up a mudflap and putting it under the filter to further protect it from road debris and moisture.

Rockwell