Scuttle mounted fuel tank?

[DaveH]

Sorry for the necropost, but you should look at the structure in the rear and how impact forces will transfer through it. From your drawing, the only thing holding your rollbar rear stays in place are two little pieces of 1x1 that will see a lot of bending load in a rear impact. They should probably be beefed up to rollbar tubes and have the front ends brought inboard a little bit if possible.

The downside is, the stiffer you make that rear structure, the more impact force gets transferred into the squishy bit behind the steering wheel.

[banzairx7]

I ended up putting the tank in the rear. The rear braces for the roll bar attach with a 14mm bolt directly to the subframe. So it's pretty stout. The 1" square is really there to support the tank. I also added that "crash bar" across the back to give the tank more protection.

IMG_20180225_160915 (Medium).jpg

[DaveH]

I see now. It wasn't clear from your drawing that the rear stays attached to that beefy stock sub-frame. What is that from? I don't immediately recognize it.

[banzairx7]

It's from an RX-8