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Air box build


NAXJA Forum User
A while back I purchased a S&B CAI because it was the only CAI that came with a true air box. It didn't fit worth crap. The air box holes needed to be redrilled to reposition the box to clear the radiator cap and still it didn't fit well after that. The other problem was that the air tube sat too high above the throttle body and was a good 1.5" above the hood line. After modifying it I still wasn't happy with the way it fit. After some words with S&B they agreed to buy it back. Sure, their product didn't fit but at least they were nice enough to buy it back. So, A+ for customer service.

I then purchased a Volant intake and a Amsoil (EAAU3590) air filter. I decided on the Volant over something like a K&N because the Volant tube was larger, accepting the larger filter. Also, the K&N did come with a simple shield but then the shield seals to the hood, right about where the driver's side hood vent is located. Sure, I could use the hood vent as an intake but I put them there to extract hot air from the engine bay. So I didn't want to take away that function.

The Volant came with a small shield for the filter it came with but I wanted to use the larger Amsoil filter. The Amsoil filter is a cone style, 6" wide at the base, 9" in length, 5" at the top, and a 3.5" inlet. The shield wouldn't fit with the large Amsoil filter nor did it do anything in the way of blocking hot engine air. It was pretty much just a dirt shield. So after much thinking I decided to build an air box with a lid.

Volant intake with Amsoil filter:

I decided to make a shield similar to K&N's, but extending further back in the engine bay to accommodate the filter location. I made the shield out of 3 pieces of .080" aluminum. One is for the rear part, one for the side and one for the radiator cap. I started with a cardboard mock up but it wasn't holding form as well as I needed it to. So I went with .020" aluminum for the mock up, which worked much better. I cut the aluminum with a combination of a kick shear and jigsaw then bent it on a metal brake. Making the shield took the better part of a day as I had to account for clearance issues with wires and other components in the engine bay. The lid was easier. I did use cardboard for the template than cut it.

The crappy cell phone pics below are of the air box being mocked up.


The air box will be sealed to the fender with weather stripping. For the larger or uneven gaps (such as the rear of the box with wires and curved inner fender, where the air tube enters the box and where the box meats the radiator support) I will use a rubber strip. I currently have a piece of rubber baseboard I am going to give a shot and see how it holds up to the engine bay temps. I painted the shield part using VHT Wrinkle Paint. The Lid is yet unpainted and I haven't decided if I will do anything else to it.



Oh.. that bracket on the rear is to hold the air tube. Its made out of a gas pedal I had previously made and decided not to use.

Now that I had the air box completed I had to get air to it. As some point Jeep decided to do away with the hole in the body panel behind the headlight. The hole was feeding the stock air box, and my 2000 XJ didn't have one. So I had to make a hole. After much thinking and posting this question here: http://www.naxja.org/forum/showthread.php?t=1063867. I decided on the placement of the hole. After masking off the area I was cutting in I did the cuts with a small air powered reciprocating saw. The saw fit perfectly in the limited space and cut the sheet metal like butter. I also cut a bit out of the fiberglass header panel and head light bucket. The blade on the saw was actually broken which made its length perfect. After cleaning the cut and de-burring it I put down a layer of POR15 engine enamel which I had left over form another project.

The saw:

The hole I ended up with:

Cut in the header panel:

I forgot how itchy fiberglass dust it.

Thats it for now. I'll be installing the shield tomorrow and maybe working on the lid as well. I'll update this thread as I proceed with the install.

Nice job. Would there be a way to run ducting from the lower air damn up to the shielded off area or would that be not worth the trouble? Something Ive always wondered about was what if you ditched the front turn signal completely (I've seen Miatas like this) and have some sort of tunnel straight to the filter area.
I didn't take a picture, but I cut the fiberglass around the headlight as well--as much as possible leaving just enough to let the headlight springs still do their job. I was using a cut and folded windshield reflector for my box until last week when I wired up the AEM. I'm gonna make another sometime. I too had a thought about a blinker funnel to the filter--there's a co that makes them for the bmw e36 fog light locations.
I didn't take a picture, but I cut the fiberglass around the headlight as well--as much as possible leaving just enough to let the headlight springs still do their job.
I didn't realize it before or when I was cutting, but the left side part of the fiver glass and the bucket are what keeps the light propped out against the spring pressure. If I had removed to much the light would have been aimed down.

It wouldn't be too hard to fab up a head light or blinker funnel, but i would get pulled over quite quick for something like that. Maybe one could even run ducting down to the air damn or where the fog lights are and get air from there.
I installed the shield today and did some work on the cover. I probably went a little overboard on the cover, but it looked a little plain. I installed the weather stripping and the rubber baseboard on the shield. I'm interested in how the baseboard rubber will hold up to engine bay temps.

Weather stripping and baseboard installed on shield:


Weather stripping against hole I cut yesterday:

Filter side of shield with baseboard fitted:

Mount on Volant CAI:


CAI installed:

Now the lid. I cut a hole in it on the router than cut a piece of 1/4" lexan so it would sit flush with the lid. I then cut a retainer for the bottom to hold the lexan and the rest of the rubber of the lid sealing. The retainer will be held to the lid with counter sunk screws.


Now I just have decide how to finish the lid. I could powder coat it blue like the valve cover, wrinkle finish like the rest of the box, or a gloss or flat black. Or I could leave it bare aluminum and give it a brushed finish.
Well, the stain is out.. most of the scratches too. If I had planned on a polished finish I would have been a bit more careful with it and would have went with a better piece to start with.
I admire your level of work that goes into your projects. It looks great so far. Do you have a way to measure the temp with and without the shield? If not, it will drastically alter the way I think about you.

Hopefully the airbox will get more oil to your cam bearings
I can plug into the OBD II port and read the AIT sensor. Since I have extended the wiring for it I could put it outside the shield, get it hot and read then put it in side the shield and read it. I also have a temp probe on my multi meter. The meter itself had a min and max hold setting so I could tie it down in the engine bay with it set on max and take readings.
Looks great!! Perhaps using some photo-shop to try out the various color/polish/etc looks would help you decide??

I like the idea of matching your Valve Cover... but that might be too much Blue once you get it all done. Whatever way you go... looks good!!
I am polishing it. Sure it might not hold up to under hood dirt, crap, and scratches in the long run, but it will look good for some time... even if it is going to be a bit bling. And it can easily be re polished or painted. I finished sanding at 2500 grit Tuesday evening and will be buffing it tonight. I'm sure sick of sanding.
Nah, no clear coat. I have heard of people clear coating it, but in my experience it will either chip off or turn yellow. I'll just keep up on cleaning it and using aluminum polish on it.
Nah, no clear coat. I have heard of people clear coating it, but in my experience it will either chip off or turn yellow. I'll just keep up on cleaning it and using aluminum polish on it.

thought about clear anodizing or powder coating at all? of the two I'd prefer powder coat from a durability standpoint but either would look pretty bitchin.