I am planning a north african road trip with my 2008 5.7L 8 Jeep Grand Cherokee .

Has anybody here ever increased the Fuel tank size on a car ?, or has anybody ever modified the fuel tank for their Jeep ? if so what did you change and why

ive seen some welders offering custom built Fuel tank services but not sure if its probable for the Jeep.

 

You could try fitting a fuel cell in the spare tire well and moving the spare to the roof. You'll probably need a couple of spares anyway. The fuel cell would be a rubber bladder inside a metal can shaped like the spare. When you need fuel, open a drain into the original tank. You could probably get at least 20 gallons into a fuel cell placed there. Just make sure it's properly sealed and vented externally.