Fuel Cell Mounting?

[BMW RACER]

Hey guys.

I'm mounting a fuel cell in the rear of my E36 enduro car and am pondering the choices for building the suporting frame. I looked in the GCR and while SCCA seems concerned about the fuel cell you use they don't seem to care how you mount it, as long as it's more than 6" above the ground!

So, trying not to reinvent the wheel and also being lazy, I was wondering what y'all think? Any drawings or pictures would be appreciated.

Thanks in advance.

[lateapex911]

John, a few questions. Fill us in on your stock tank. IIRC it's rather unique, right? Isn't it sort of a saddle tank located under the rear seat area?

If so, you have lots of mounting options.

What are your goals??

safety?
Dry break application?
Aerodynamic improvements to the under car area?
Changed weight distribution?

What cel have you selected?
What mounting provisions does it provide?

Using the 12" rule, you could mount it in the passenger area...if you wanted.
Or the trunk area is OK for you thanks to the line item exception (trunk would be more than 12" away I think, in your case)

Depending on your answers, the mounting will be affected

[tderonne]

How big is your cell? A 15 gallon cell will weigh nearly twice what an 8 gallon cell does. But lets guess a 15 gallon for a minute. 15 gallons of fuel is around 100 pounds. Mount it as you would something else that weighs 100 pounds. That is, 100 pounds of ballast, a couple batteries, or half a driver. Mine is only 8 gallons, so it has no frame around it, just an extra tube on one side and frame rail on the other.

Protecting it is also important, especially when you put a cell where there is a crumple zone.

The Ford Racing Grand Am Cup racecars have no frame either, by the way. They are 20 gallons if my memory is right, limited to 18 actual by the rules I think. They use a custom can that is double thick and the top flange gets welded to the trunk floor. It pushes the limit of not being reinforced in some way in my mind, but it works. Not really sure if one has been crashed good enough to really test it though.

[Joe Harlan]

John, Mine is a 10 gal in the 240sx but I did it this way to make it easy to install my 22 gal cell for enduros. The need for the mounts was to keep the cell above the 6" rules as it is pretty deep.

[Mike Mackaman]

I built a cage to hold mine out of 3/4" square tubing, three loops in the long axis of the car and one down the middle of the cell. I use two section s of square tube on top to hold it in. This is overkill, but it also serves as a jacking point and a nice place for the jack stands in the back. Now that the minimum weight for the 260 is lower, I may have to rethink this but it has worked well for a long time.

Mike