This is how I did my cowl snorkel, based very closely on srmitchell's thread http://www.jeepforum.com/forum/f11/m...norkel-727684/
Frankly, I was intimidated by piecing together a solid tube out of PVC. My work with PVC is exceedingly limited and all the geometry seemed overly complicated, so I opted to use a universal intake tube based on a TV commercial I remember as a kid for a product which I think was called "Flex Jars."
I got the tube from my local AutoZone for $20. AutoZone.com | Air Duct Hose | Black air ducting
I removed the air box, cleaned it up and used the tube to get a rough idea of where it would need to go. I marked and drilled a small hole in the center of where I wanted to place the tube.
I cut a strip of plastic and drilled two small holes in it 1½" apart as my template for the hole.
I used the drill bit as a hub and drew the circle I would cut with.
I have a pneumatic trim saw I'd planned to use but my compressor is at my parents' place so I used what I had on hand, which was a simple coping.
I drilled a ¼" hole as a starting point and reassembled the coping saw with the blade inside the hole.
I proceeded to cut out the air box with the coping saw. When done, I used a Dremel with a sanding wheel to smooth the edges.
I again used the tube to determine a rough placement and used my template to draw the circle which I would cut out.
This is the hole one everything was cut out. It turned out quite ragged as I used a Dremel with small cut off wheels. I smoothed it out with a grinding wheel before installing the tube but I was excited the hole was done and forgot to take a picture.
I mounted the tube up as high as a could so that the base of the cowl would act as a dam to keep water from entering the intake tube.
As srmitchell had warned me, this did result in the tube making contact with a rib on the hood but since I used a flexible plastic tube, I don't think it will be a problem.
And much of my reasoning behind adding this mod to my relatively stock rig is because a photo I saw of one of my fellow club members with a significantly bigger XJ than me in a water crossing I know I'll be facing soon.
I used OSI Quad, which is a heavy duty construction adhesive and a great caulk, to seal things up. I cut a block of Trex composite deck board 3"x2-1/8" to fill the factory intake hole. I painted the outside of it black for the sake of color uniformity.
I positioned the block and pre-drilled holes for 4 screws to hold it in place, not that they'll be needed once the Quad cures. I then removed the block, caulked along the opening, reinstalled the block and screwed in the screws. I then caulked in all the factory drain holes as well.
I inserted my tube and caulked the outside well and the inside as best I could.
I clamped it in place to work on it and left it sitting to dry overnight.
This is where the tube enters the cowl.
The tube came with two oversized sleeves to finish off the ends. I trimmed one today and put it inside the cowl as a retainer. The other will go inside the airbox.