Bumper Beam Water Tank
After I made the decision to go the Active Interchiller route I knew that I also needed to add additional water volume to the system. Since the AC compressor kicks off at WOT, you want to have a sufficient mass of water available to keep the intake charge cold. I use a Rotofab intake box for the Maggie, that eliminates the one corner of the engine bay where there is some real estate available. I took the front bumper cover off in search of more space. There is some space on the passenger side, but it is still fairly small and irregularly shaped. It would be difficult to get something fabricated and mounted securely in that area of sufficient size. I would need to modify the existing bumper beam to mount the extreme chiller I was installing. The thought occurred to me that it would be a great place to have a tank. A quick measure of the size of the beam and it was pretty much exactly 3" deep and 4" tall. Making a tank would be real easy if I can find some 3" by 4" rectangular aluminum tube. I was able to find some at Metals Depot, stock T34318. 1/8th inch wall thickness:
https://www.metalsdepot.com/products...cc=%20&aident=
I ordered up a 4 foot length. After it arrived I got to work. The stock bumper beam has a gentle curve in it. My aluminum was straight. I compared the two and also looked at how the plastic bumper support went on. I came to the conclusion that it should still work out well. First off I cut the aluminum down to a 42 3/4" length. The tank is basically a trapezoid with a 42 3/4" width at the back and a 36 1/2" width at the front. I used a jigsaw with a metal cutting blade to cut the aluminum and make a tab on the front surface. My tab was actually larger, therefore the overall tube length was over 42 3/4" on the front. I ended up with some interference with the weld and the mounting holes after washers were installed. I think using the 42 3/4" length on the front will work out fine. I bent the tab over mostly by hand to start it. I moved it into the final position with some persuasion with a 2 X 4 and a hammer.
Holes were drilled in X position, Y diameter (to be edited later) so the tank could be mounted using the same threaded holes on the outside of the frame rails that the original beam used. The original beam also used additional holes that were more inboard. These were not used and are covered by the tank.
Need a way to get the water in and out of the tank, so I ordered two of these:
http://www.ebay.com/itm/3-4-HOSE-BAR...BXPMaA&vxp=mtr
I drilled holes centered 3 1/2" in and 3/4" back from the back edge of the tube for the bungs, one on each end. You definitely need to have a bung at each end so that the water/coolant flows across the entire thing and does not stagnate at one end. I would probably recommend taking the 3/4" measurement up to 1". This would give the welder a little more room and will not cause any other issues.
Something the prototype does not have and would be a good addition would be an additional threaded bung on the top side of the tube. This could be used to bleed air from the tank and would normally be capped with a plug.
I also cut two 2" width 1/8" thick pieces of aluminum to use to mount the chiller. These were centered at Z" to match the mounting points of the 19" chiller. If you use the smaller 13" chiller your width will be different. These tabs could also be left off completely if you are mounting the chiller somewhere else such as a vertical mount over on the driver side that is offered. This talk would still be handy for that setup.
After all the cutting and drilling was done it went to an aluminum welder to seal up each end and weld on the bungs. They also pressure tested it.
After I got it back it was time for a test fit.
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