Here's a cheap alternative to spending $150+ on a K&N FIPK. Get a K&N drop in replacement filter for around $40. You will notice that the filter fits into grooves on the top of your airbox (at least it did in my 95 5.8). Loosen the two hose clamps on the top of your airbox that connect the hoses from the throttle body to the airbox and remove the top of the airbox. Flip the top of the airbox upside down, and because the hose hookups are symetrical, the box will hook up to the hoses exactly the same. Stick in your K&N replacement filter and you have an instant open element air filter. I temporarily fastened down the filter, even though it's a pretty tight fit, with a couple scrap pieces of wood along the long sides of the filter with long zip ties going across the filter from bolt hole to bolt hole. I used the wood to more evenly distribute the pressure along the edge. I also temporarily held down the flipped box with zip ties looped through the bottom of the airbox. When I get a chance, I'm going to make a wood frame that goes completely around the perimeter of the filter with holes drilled through it to secure the entire assembly to the bottom box with longer bolts, but zip ties do the trick too. I can't officially say what effect this has on performance or mileage, but throttle response and the sound are greatly improved over having the K&N in the stock airbox setup. When the transmission kicks down and the engine starts to rev, you get a great sounding mellow roar with a nice little hiss of induction noise, but when driving normally it sounds the same. I have trouble keeping my foot out of it, and this is with an otherwise stock truck.
Let me know what you guys think of this, I joined this post so I could share this idea.

 

You can also cut the bottom off the lower part of your airbox. Then you have a rim around your filter that holds it to the upper part of your airbox. Saves the woodwork...

 

i created my own open element intake for an 88 I-6 using a filter ment for an airiad induction system off of a 99 expedition and right about peak torqe i got the same sweet sounding intake hiss/whine that faded out as the engine revved up and got louder. my dad made me take it off cause he said it screwed up the emissions but i have the reports saying they got better with the intake after failing with both setups. i also talked to our mechanic who we know real good and he said it isnt a problem. so im gonna put it back on and get a high profomance muffler from advanced auto and see what happens.

 

would doing that be ok if you live on country roads because of the dust and stuff

 

>would doing that be ok if you live on country roads because
>of the dust and stuff

If you drive in dusty conditions you will have to clean the filer more often. It may be better to have a K&N, cause you wash the filer to clean it, and a paper you throw away and have to buy a new one, and the paper ones add up after while cause you have to change them because of the dusty conditions.

 

According to the 'flow' numbers posted by K&N, most dirty K&N filters will flow nearly as much air as a clean paper unit. Driving in dust is going to get to any filter no matter the setup. The engine needs air and it comes from outside.

As far as using wood to hold your filter it sounds like you are taking a chance on allow 'raw' air into the motor. Most people are going with the guy that cut the bottom out of his box. This allows the stock box to seal the filter properly while allowing more air into the engine. Take the cold air intake hose from the front of the grill and use some wire ties to hold it to the bottom of the box, pull it out of the airbox input hole as that's a huge opening for air. Take a 1/2 drill bit and make swiss cheese of the bottom and sides of your box and you'll have 80%+ of the air provided by an FIPK.


1994 Black/Silver F150 XLT 4x4 Reg Cab / Short Bed, 3.55 LSD, 5.8L w/84k miles, K&N drop-in
Upgrade wish list: 31x10.5, Gibson exhaust, helper springs, lights

 

muddhog\hey dm7 tell me a little more on how you moved the front grill cold intake hose.

 

The Intake Snorkle on my '93 is removable, so I did just that, and when I did I found that the opening that goes into the airbox is only 1/3 the size of the hole that the snorkle fits into. If you do the math, the volume of air that passes through this snorkle end is not enough to supply the engine. I used a 1/2 inch drill and drilled a bunch of holes into the tapered snorkle end thereby allowing a whole lot more air to flow into the airbox. I ran with and without the snorkle and found no difference in performance, but then I don't have a modified exhaust either. Another option is to cut the end of the snorkle off just past the bumps the snap it into the air box. I found that running without the snorkle the air filter got dirty faster from dust coming up from the front wheel.

 

The reason that I flipped the top of the airbox instead of removing the snorkel and drilling holes is resale. All I have to do is flip the top of the box back over and put back in the original bolts and the truck no longer looks like it was worked on by a shadetree mechanic. Help me get more money for my truck if I ever get enough for a Super Duty with a power stroke. The K&N is a tight press fit into the box, I'm not worried at all about the possibility of dirt getting in around the edges. Also, in response to the dust question, I had a K&N cone filter mounted inside the fender of my last car where it could act as a kind of half assed cold air intake, and I only had to clean it probably every six months or so, and it was exposed to a lot of dust. I do agree that if you tried this with a paper filter you would eventually spend a fortune replacing them, and the benefits wouldn't be as great. This idea seems to be getting plenty of critism, but anybody interested should try it if they have five minutes or so to spare, you can always put it back and it makes the truck a lot more fun to drive.

 

>You can also cut the bottom off the lower part of your
>airbox. Then you have a rim around your filter that holds it
>to the upper part of your airbox. Saves the woodwork...

Alright, I have an 89 150 w/ a 302 EFI. Say I want to get a K&N filter and use stock airbox and hoses to throttle body. I could cut the bottom out of my airbox and leave enough lip there to hold the filer. Right? My question is, my truck has a small crankcase filter in the airbox with the filter. What do I do about this filter?

 

>>You can also cut the bottom off the lower part of your
>>airbox. Then you have a rim around your filter that holds it
>>to the upper part of your airbox. Saves the woodwork...
>
>Alright, I have an 89 150 w/ a 302 EFI. Say I want to get a
>K&N filter and use stock airbox and hoses to throttle body.
>I could cut the bottom out of my airbox and leave enough lip
>there to hold the filer. Right? My question is, my truck
>has a small crankcase filter in the airbox with the filter.
>What do I do about this filter?


amsnss, That's a very good question! One that I would like to know about, also. If anyone has done this, please let us know how it worked out. I think this would even help with the stock filter in place. More air has to be better!! I have a 95 150 A/T 302.

 

You can use a standard, round push-in breather filter. Just cut the hose at the filler and push the breather filter in there.

 

that was a good idea about the home made fipk. For the breather I would get a plastic hose coupler from the parts store or I think I saw some at the hardware store used for splicing plactic water line that were about the size of the breather hose. then i would drill a hole in the base after I flipped it upside down and insert the coupler in the hole and use some epoxy to secure the coupler to the base then attach the breather hose. Then just cab off the coupler if you ever wanted to reverse it back to the original state.

 

Whay all the bother about exposing the whole surface of the air filter? It won't flow anymore than the 2 hoses to the T body anyway. Instead of butchering the airbox just remove the snorkle by pulling the 2 buttons that hold the intake to the radiator crossmember then pull the snorkle out of the air box, a tough pull, use side to side movement, pull hard comes easy. This will leave you with a large enough openeing to flow all the air that the engine will use and doesn't ruin the box and it can be returned to stock for resale. Now if it is the "look" that you want a trip to you local plumbing supply hose is in order. There are adapters made for plumbing old cast iron to plastic or copper pipe that will work for this project then all you need is a couple of round K&Ns with the appropriate sized hole. The local speed shop should be able to source these for you. The K&N book gives all the dimensions of their products.