Designing A New Fuel Tank
One of the most important aspects of an expedition vehicle is the range in which it can journey on a single tank of fuel. Often in remote locations the availability and reliability of fuel are both concerns. My target range is 500 miles, as I have found generally this is about the farthest I ever need to go without refuelling. In a perfect world I would like this to be accomplished without the added inconvenience of having to carry a number of jerry cans. My ultimate goal has always been to carry one jerry can for the added sense of security if I ever reach that “Oh no, I think we are running on fumes” feeling. I remember vividly how often I stood beside the roadway filling my Land Rover Series vehicle as it only had a tank range of about 125 miles. It gets old fast!
The stock Unimog fuel tank is 90 liters (about 24 gallons). The fuel economy is between 14 and 9 miles per gallon depending on the conditions. This allows for a range of only 336 miles in the best of conditions and about 216 miles slogging through mud and puddles in Central East Nowhere. Not acceptable, and not worthy of a true expedition vehicle.
I have begun the task of designing, building and installing a custom fuel tank. After several hours with a tape measure, cardboard, tape and several design revisions the plan is coming together. My custom tank should fit approximately 58 gallons of diesel fuel (220 liters), giving me a travel range of between 812 miles in ideal cruising conditions and 522 miles battling through the jungle.
Photos from top to bottom (click on photo for larger view): (1) The original tank as installed and only containing 90 liters of diesel. (2) My cardboard template of the new fuel tank (220 liters) and custom designed to fit around side step structure of the existing vehicle. (3) Cardboard template is now providing a perch for our cat Rover. (4) The tools of design and calculation. Measurements ready to go to the fabrication shop for our next step.