Took a trip down to the local Lowes to figure out what I would need to build a shroud. Turns out that this 3" PVC pipe coupling is nearly a perfect fit. There is a ridge inside the coupling which needs to be ground away a bit for the lens housing to fit through it. I drew a line with a sharpie along the ridge for reference and let the Dremel loose on it until it was a snug fit over the lens housing. This picture also shows where I had to scallop 'drop zones' for the cutoff shield on either sides of the slots. You need that space or the shield won't drop for the high beam. This is critical because if the shield interferes with the shroud at all, it will get stuck in the high beam position. I also cleared some room for the screws and mounting pins for a flush fit.
Also had to grind a little bit off and bevel edge the bottom part of the shroud where the cutoff shield was binding on it.
Now before you permanently seal the shroud to the projector, remove the lens from each projector, put a thin bead of clear silicon on the lip where the lens sits and reassemble it. Like the rest of the projector, this part isn't originally watertight. Make sure you push the lens all the way back in and snug it up with the locking ring and bendable tabs. Any excess silicon pushed out on to the lens should be cleaned up promptly. Unfortunately, I don't have any pics of this forgotten step.
Once I was satisfied with the fit of the shroud and certain that the shield would not bind on it, it was time to seal it to the projector. Lots of aluminum tape sealed all the gaps between the reflector bowl and the PVC shroud. I wrapped some more around the whole shroud to give it a neater appearance. The corners around the screws holes are tricky and they need a liberal dose of silicone for a watertight seal. Don't be afraid to use lots of tape - the stuff is thin and it takes a few layers to build a strong seal that can be handled without fear of puncturing it.
Sealing the bottom and the back of the projector is a lot more involved. I cut some pieces of clear polycarbonate packaging to form shields around the exposed parts of the high beam solenoid and the cutoff shield. I put one piece around the bottom and securely taped it in place. I then cut another piece that follows the curve around the rear of the housing and extends down to the solenoid, and taped it up too. Any remaining holes and cracks, like where the polycarbonate piece meets the neck of the reflector bowl, can be sealed up with silicon. Again, use lots of the stuff to make sure you have a good seal. There are many little seams and crevices that will need to be siliconed up. Although I didn't do it, there is a hole in the wide part of the reflector bowl which is an excellent place to mount a vent tube. You need this because no matter how hard you try, a very slight amount of moisture will eventually get inside. The vent tube will keep your lenses from getting fogged up. Here's the projector totally mummified in aluminum tape. Note the silicone around the solenoid pigtail.
See the bezel around the lens? That's Walmart to the rescue! I picked up a couple of travel mugs from the automotive accessories section. These mugs have a stainless ring around the lid that pops right off and it's a perfect fit, both around the lens and the PVC shroud! For more bezel and shroud ideas, check out this thread at HIDplanet forums
http://www.hidplanet.com/forums/view...f5fc57605caa25 You will have to register to view it though. Lots of creativity on that board!
Next, once I figured out exactly where to mount the projectors, I had to build a mounting and aiming rig. I based mine on the design in this thread
Retro - BiXenon E46's in a 1997 Z28., but added a lower mounting point for extra stability. Mine is also not as tall, and it allows the the projector to tuck in as high as possible. I used 1" x 1/8" aluminum flat bar for the top half and some Walmart angle brackets I had sitting around for the bottom part. I didn't feel confident enough to build it all out of one piece without a vise, therefore the two-piece design. That long screw threaded into the angled aluminum piece on the bottom part is for vertical adjustment. Tip: drill all holes slightly undersized for your screws and tap them. The fewer nuts you have to use for assembly, the easier and simpler it is.
I originally didn't want to cut anything out of the headlight assembly because I wanted to be able to put the whole thing back to stock if need be. However, for a couple of reasons, I decided to move the projectors as far inboard as possible. First, I didn't want the goofy airbrakes deploying any higher than absolutely necessary. Second, it turns out that mounted anywhere else, either the back of the projector would hit the radiator cross member, or the lens/bezel would hit the bumper (another reason to study the FX bixenon option more closely). This view of the passenger side from the front of the car shows where I had to do some trimming. I cut a wide slot across the top, another one down the inside, and a 90* piece out of the bottom. I lost some of the pivot area for the stock headlight basket but I think they can still fit back in there since no mounting points have been lost.
This view of the driver's side headlight from the top shows how I mounted the projectors. Two screws go through the top - the one on the left being nearly in the center of the mount and therefore very close to the reflector bowl, so use washers. You want the other hole on the right in the plastic part to be a slot, so that you can make horizontal adjustments. Another one goes through the bottom.
As far the electrical bits and pieces, I used this schematic to build a heavy duty circuit for the increased current draw from the 80w bulbs I am using. Mine draws power through a fused 12-gauge wire directly from the alternator for maximum possible juice.
Since the E46 bixenons use a 3-wire harness for high beam control, you will also need this nifty little solid state controller that hooks up to the factory high beam wire. This little guy greatly simplifies what would otherwise be another circuit full of capacitors, diodes and yet one more 5-pin relay. Probably costs less in time and parts too!
Write-up: BMW E46 bixenon projector headlight conversion for LT1 Firebirds 
- 2001 Black Formula --- 75th Anniversary Package --- 
