Something I've been wanting to do for a long time is seal up the factory airbox so that you can use it for a snorkel or to just get the intake higher up. I don't know about everybody else, but my 98 D sucks water in like theres no tomorrow if i get just barely too deep in a.... well.... puddle. so i wanted to take care of that issue. Heres how i did it.

Parts Used:
1. Spectre Performance 8148 Air Duct Mounting Plate
2. Spectre Performance 8771 3-3/2.5" Intake Coupler
3. Spectre Performance 8698 Chrome 3" 90° Elbow Air Intake Tube
4. Spectre Performance 8741 Black 3" Air Duct Hose
5. Some Silicone of your choice. Just needs to stick to plastic and block water

Special tools:
1. Dremel
2. Drill with drill bits

All other tools can be normal everyday hand tools.

All of these can be bought on Amazon, But O'reillys and Advance Auto carry a lot of Spectre products as and you should be able to get them there as well.

1. I took the airbox out of the truck to do this, which is easy. Undo the clips and pull the lid up (I like to undo the clamp and take the lid completely off when doing this, just gets it out of my way) take out your air filter. On the corner of the box closest to the firewall and passenger side fender, there is one 10MM bolt. Take that off. after that, there are two threaded studs, one inside the airbox, and one just outside at towards the front of the truck. There are little plastic "bolts" in rubber grommets that fasten to those. i don't know if mine are ruined or if they're supposed to be this way, but spinning them does nothing, so just pull up and they will let go of the studs. Now your airbox is out.

2. get the original (LEAKY) breather tube out of there. I didnt care about mine as i know its never going back on anyway, i just pried it out with a big flat tip where the sort of rectangular indention is in the bottom of the airbox (Top according to picture) it broke mine a little bit but it doesnt matter because that's not going to be used anyway.



3. Make room for your new 3" Mounting Plate. I used a dremel with a cut off wheel and cut as close to flush as i could, then used a deburring/grinding bit to smooth it out. if you spend some more time on this part you can make yours a lot prettier than i made mine, it wasnt a concern to me so i didnt.



4. Seal the holes in the bottom of the box. The plastic "bolt" that i mentioned earlier has to go. I don't trust that old rubber grommet to hold up to the situations im gonna put it through. I drilled it out from the outside of the box with a 3/8 drill bit while holding it still with some channel lock pliers. Eventually you will go through enough that you you can take a big #3 phillps or something similar and push the remaining through the grommet. Then you just have to get the grommet out. Not hard, just push it out from the inside. If its too stiff, use a small flat blade or cut notches in it with a razor blade.

Once that's out, use something like a little piece of plastic (I used 1/16" aluminum stock, its what i had laying around) and silicone it over that hole. then silicone inside to make sure you got all the gaps. theres one more hole in the bottom most part of the airbox that comes down to a point. this is your drain, your lifeline if you do get water in the box. That being said, by sealing this hole, you better make sure you never get water in your airbox again.. so you get the picture, put some silicone in that hole until its sealed good and you're done there.



5. Mounting your 3" Plate. You will have to cut off one of the corners to make it look like the one in the picture with your cutoff wheel on your dremel. That corner goes to the side of the airbox next to where the front mounting leg sticks out and down at. Now test fit it to find that you will need to trim back one of the interior strengthening ribs on the airbox itself. The rib to trim down is on the lower corner next to the one that you had to cut the Mounting Plate to fit. I know that's confusing but i forgot to take pictures of that part. Dremel it down flush and far enough that your Mounting Plate can sit flush on the airbox inside.



6A. Now you need to drill your holes. That was a little interesting. What i did was i put the 3" Plate inside exactly where i wanted it, then i put the drill inside my airbox and drilled the bottom right (according to my picture) hole. After that i moved the Plate to the outside but in the same orientation (Flange sticking out) And i just put a bolt ( 1/4X20X3/4" ) into that same hole from the outside then got the Mounting Plate as close to correct as i could remember and drilled the other two. Be mindful of how big the gap is between your flange and the rectangular cutout part because you have to fill that hole with silicone.

B. now to seal the flange. I put a small bead of silicone all the way around the flange on the Mounting Plate where it would contact the airbox. I then put it all together and tightened down the bolts with washers and lock washers, with silicone in the bolt holes to seal those. And as if that isn't enough, i did an entire bead of silicone around the outside of the flange, including the rectangular cutout towards the bottom. Clean off any excess silicone from the Flange and you're good. let it dry for at the very least an hour.



7. Now for your new Breather Tube. The tube itself threads into the rubber 3' mounting adapter. If you trust that, then you're done here. I don't trust it, so i siliconed the threads, then once i had it threaded in, i put a bead of silicone around the inside edge as you can see in the picture. Now you're done with the tube.






8. Now that you're done with all of the siliconing and its now drying, theres one last thing before you can put it all back together. The threaded stud from your fender, that needs to go. dremel with a cutoff wheel, done. that was easy right?






9. Now you're done with all of the hard stuff. Just undo the chrome clamp on your 3" 90 angle pipe and itll come off so that you have a normal 3" 90 angle you can use. Take your Intake Coupler and take the 2.5" adapter out of it, you don't need that. you should be able to slide the coupler all the way on the 90 angle, then tighten that clamp. Once all your silicone is good and dry, put the box back in, put the 10MM nut back on, and pipe the system however you want. As you can see, mine is piped up to being right below the hood for now. Snorkel comes later, just not ready for that project yet. Hope this helps!

 

Nice work. My dad's old Catalina and Delta 88 have this bit of ducting that is about 1/2 of an inch tall and a foot or so wide that would suck cold air in from the gap between the hood and the radiator, I wonder if you could get one of those to fit there and use it to suck in air from the cowl since you have the tubing there now.

Kind of like these but a lot thinner and wider

 

That's a pretty good idea actually. Now that you mention it, i have seen those before. My brothers subaru had one that did exactly that. The worst part about this setup is that its now sucking in hot air and i really need to fix that. Im hoping to have the snorkel done in a couple weeks so that i wont have to worry about it anymore lol