2016.06.021 - UPDATE!!! - WEEKEND OF MANY TANKS!!!!
Boy ain't that the truth?
I did a lot of scaled-drawings and set up my tablesaw in the side yard to cut another sheet of MDF into new and interesting shapes to see if I could build a single, center-mounted tank capable of reaching my 32 - 35 Gallon target.
Most of my original designs gave me a center tank with about 20 - 25 Gallons, depending on how deep I made it. They also made it tough to get the exhaust routed through the area the way I need it. So the new objective was to keep the tank as "invisible" as possible (when viewed from the side or back).... improve exhaust routing and clearance near the tank, and also grow the capacity by at around 10 gallons over previous efforts.
The most logical answer seemed to be to extend the tank back closer to the rear axle, but create some 45-degree angles so that the exhaust could sneak under the upswept portion of the rear framerail and head to the rear corners of the bedsides. There is a limit to how far back I could go before hitting the mufflers, and the depth was limited by clearance to the pumpkin at full-stuff. However, with a bit of experimentation I got this:
That trapezoidal area added about 7-1/2 gallons to the 24-1/2 gallons in the front part of the tank. That gives a total depth of 12" . It all seemed awesome, since I basically hit my target instantly... but the problem was that the sideview is not what I want at all.....
It turns out that the lowest I can go in the rearmost part of the tank is about 10.5" deep (not including skidplate thickness) so the 12" deep and flat-bottomed tank has an ugly corner sticking down..... add a beefy skidplate and small air gap between them, and the overall look is not going to work for me.
So I had a few more options: Taper the tank on the bottom by 5.5* to follow the natural taper of the rear bedside design.... or find some extra capacity somewhere else. The hard part is that I'm still working with a bedside that doesn't fit right because the wheelarch is in the wrong place (set up for factory 104" wheelbase instead of my current 107" wheelbase)... and when I lay-out the truck on the bumpstops the fender hits the tire.....A LOT!!!
So I did one of these:
Which gave me the cutting guides I needed to cut-off the rear half of the bedside and shift it closer to where it will eventually need to go.
The wheel arch is a total hot-mess right now, with too much gap in the front and a curve that needs a ton of massaging to give it a "stock" appearance so that it doesn't have a big 4" straight section running across the top of it to connect the two sections. Not of that was unexpected, it's just an "I.O.U." that I knew I'd need to write myself so that I could get the bedside into the proper location and see the departure angle and figure out where the rear bumper was going to end up.
I still have not installed my old rear hidden hitch crossmember (the one that incorporates the license plate holder but converts to a D-ring shackle setup). I was hoping that I might be able to find a little more fuel tank room once that crossmember was re-installed. However, based on where the bumper get bolted on.... there really isn't a lot of "extra" room behind the crossmember for me to extend the tank rearward,
So.... the fine-tuning and head scratching continues. I feel pretty confident that with some more refinements, I can get to my 32 - 35 Gallon target and still keep things tucked up and well-hidden so that the tank doesn't create a huge visual distraction when its finally installed.
NOTE: All photos are taken at "full bump"... which is why it looks so low to the ground in most of these photos. For exhaust / axle clearance checks it was important to do all my experimentation while sitting on the bumpstops.
-G
) you could graft in a newly shaped flare without messing around with extending the current one or pie-slicing it up. The toughest part would be recreating the seamed lip around the very edge. A bead roller might be a decent way to do that.
