The disclaimer:
If you decide to do this, I accept NO RESPONSIBILITY for any adverse effects that you may experience. I am simply relating what I have done to MY personal vehicle. This process may or may not be emissions legal in your state, please check local regulations before attempting this. No animals (not even a Mustang!) were harmed in this process. All rights reserved. Void where prohibited. Side effects may include dizziness, elation, and a stupid grin.
The materials:
Aluminum sheet- I used aluminum roof flashing material available at the local hardware store (In my case Home Depot) in rolls. I selected a 12" wide material, and as long as you have at least about 4' of length it should be fine if you don't make any mistakes. About $7.
Aluminum tape- This is also available at the hardware store, it is normally used for sealing heating or A/C ducts in the home. About $4 per roll. 1 roll is plenty!
Insulating material- I decided to use "art board" available from the local hobby shop. This is a sandwich of posterboard with styrofoam in the middle. I decided to use a 1/2" thickness. A poster-sized sheet is about $4.
Gap sealing- I used the material that is made to go around window-unit air conditioners to seal the gap. It is a foam material, very flexible and spongy, also available at the hardware store for about $3. I selected 2" sqare to be sure of a good seal.
Small filter for the air pump. I got one at the local auto parts store for $2.99. Be sure it fits the hose to the airpump.
Cardboard for the pattern- I used the box my strut tower bar came in... but you could use anything, such as posterboard, an old beer/soft drink 12-pack carton, whatever.
The tools:
You will need a 10mm wrench, (I suggest a socket and rachet, but to each his own...)
some sort of cutters that can be used on lightweight metal, (I bought a set of shears from the local hardware store, about $12 for the set of 3!) (one to cut straight, one for left curve, and one for right curve) a felt-tip marker, a drill with approximately 1/4" bit, and a knife to cut the art board. (I used a serrated kitchen knife for this... high tech, huh?)
The procedure:
I did this in conjunction with the filter and AFM (Airflow Meter) adapter install (saves extra steps) but it could be done later. I will describe the entire process to keep it simple.
First, using a 10mm socket I removed the 3 bolts holding the airbox in place. Unplug the hose from the airbox to the airpump. (I removed it entirely temporarily.) I found it easier to disconnect the AFM from the hose to the throttle body as well. Unplug the wires to the AFM, and you can now remove the AFM and airbox as one unit. There are 4 10mm bolts that secure the AFM to the airbox. Remove these and separate them, and set the airbox aside.
If you want to keep it looking neat, now is a good time to remove the brackets that hold the airbox in place. (I suggest saving all these parts in case you want to return the car to stock at some point!)
There is a gasket between the AFM and the airbox. I suggest CAREFULLY removing this to use for a pattern for the holes you will have to make in the new cold-air box!
Now loosely attach the AFM to the hose running to the throttle body. When we reinstall the AFM it must remain PERFECTLY HORIZONTAL or it will adversly affect the mixture, emmissions, and driveability of your car! Please keep this in mind when making your patterns. Carefully trim a section of your pattern material to match the curve of the inner fender panel at the front of the AFM, and to extend across to a point approximately even with the edge of the radiator. Hold it in place against the AFM with the AFM held horizontal, and trace around the AFM with the felt-tip pen. (just the upper 2 corners will actually be adequate to give you a place to position the gasket to complete the pattern. Please not that the lower inside corner will probably rest on the air conditioner line if the car is so equipped.
Take the pattern that you have made, and carefully position the gasket that was removed from the AFM using the marks you just made as a reference. Mark the rectangular hole in the middle, as well as the 4 bolt holes. Cut a sheet of aluminum to match the pattern, and drill the holes for the bolts, and finally cut out the rectangular hole in the center. Repeat this for a second sheet, then using the bolt holes to align the AFM adapter and trace around it. Cut this out slightly oversized. Use this sheet to mark the artboard, and cut it to match. Use aluminum tape to attach the artboard to the second aluminum sheet on ALL edges, including the ones on the hole in the middle, making sure that the aluminum is on the side that faces foreward.
Then attach the first aluminum sheet on the opposite side of the artboard again on all edges with the aluminum tape.
Wrap the A/C hose with something to protect it from rubbing (I used aluminum tape... useful stuff!!!)
Remove the AFM from the hose to the throttle body again, and put the gasket in place, followed by the part you have just made, and finally the AFM adapter for the filter. Secure it with the 4 bolts that held it to the airbox originally. Now reattach the AFM to the hose that runs to the throttle body, and plug the wires back in. Use aluminum tape to secure the bottom and side of the part you made to the inner fender and frame rail below. Seal all the gaps- we don't want hot air coming in there!
Now make a pattern that runs from this part to the front of the car. I made 2 parts here- one that sits at about a 45 degree angle to clear the A/C line, and a smaller vertical one to fill the gap from the top edge of that to the bottom of the hood. It has has a cutout to allow the use of the original cold-air snorkel that runs across the top of the radiator also. Repeat the aluminum/artboard/aluminum "sandwich" used in the first part. Attach all parts with aluminum tape, and seal all gaps with the same material.
I then removed the rubber part that seals the hood to the back of the headlight door, and turned the little corner part back out of the way and secured it also. (with what, you ask? ALUMINUM TAPE of course!) (Ok, I used duct tape for this... hehe) I also removed the Flash-to-pass lense on that side to allow more cold air into the headlight area, which will then travel back through the area that we just removed the seal from. Use the foam "A/C window seal" material to make a seal between the hood and the rear and side edges of your new cold air box... I covered it with black duct tape. That's all there is to it! I spent about 2.5 hours doing this...
The results:
Was it worth it? I think so! I seem to feel an improvement in acceleration. (scientific evaluation of "Butt Dyno" results!)
your results of course may vary. I have added a couple of pics below so you can see generally what it looks like.
