Baja Prep: Fuel Cell

Every design element of the car has been re-evaluated, and yes, that means this is a LOT of work to figure out new solutions for old problems. One of our problems along the way has been fuel capacity. It sure doesn’t sound that bad when you say your race car has a 150 mile range, but when you are stuck in the middle of no where… well, a little more range sounds pretty good.

Originally we built our car around a 15 gallon fuel tank. Our car gets 9-11 mpg, so average about 150 Miles per tank depending on conditions. What we have learned is: Carry more fuel. Well, since we originally designed the car with our fuel cell in the stock fuel tank location (or as best as we could get) we didn’t have any more room for fuel up front, so that means we have to move it all to the back. This has a few complications: First, we had to find a new home for our spares and our battery. Second, we needed to make sure we considered the transmission as part of the equation.

So lets start with #1: Spares.
We carried 2 spare tires previously, a Jack, CV axle, small parts, steering parts and a few other odds end ends, plus, of course, a set of maxtrax. Spares are an interesting conundrum by themselves. First, every spare part you add to the car is more weight in the car which adds to the abuse that the car will take. However, without the appropriate spares on the car the car can not self extract and it becomes more reliant on the chase team. So. How do we combat these challenges. We have decided that one spare tire will do. Minimizing weight, while carrying spares with fewer redundancies will hopefully take a little more stress out of the car, even if it is 10 lbs here and 20lbs there.

We are moving the spare up front. This is pretty typical of these cars, any car with a fuel cell in the back has a spare up front. We have been test fitting with the biggest tire we have and so far… no problems.

The battery is next, that we are trying to find the bests home for… Once we have a few more pieces in place we will have some more information on that we will make a new post.

This means we have to figure out our second problem: The shift linkage attaches to the transmission just below the best possibly place that the fuel cell could go. So… How do we get a fuel cell in here without making it a huge pain in the butt to replace the transmission? Well, its a nearly impossible question, but we have have determined that we can set the fuel cell back just enough and up just enough to provide clearance under the cell to allow for the linkage bolt to be accessed. We started with a mock up of the fuel cell made out of dowels so we could judge the difficulty of this problem:

Then we moved onto the real deal after we decided this cell would work with our problems.

With this space we should be able to access the bolt from over the fuel cell, reaching between the cell and the firewall or through an access hatch we made in the firewall between the seats. Lets be clear, Nobody is going to volunteer for this job because it will still be a pain, but it will be much better than trying to lift the fuel cell in order to access this bolt.

The new Fuel cell is from Pyrotect, it is 22 gallons (adding 7 gallons to our capacity) it has a nice 45 degree cut in the cell that fits nicely against the stock VW luggage tray and is exactly the right height to fit through our rear window. We originally had plans for a fancy custom fuel cell… but that was a bit price prohibitive.

While installing the new fuel cell we also needed to create a FireWall. The Score rules require a firewall that is 1″ taller than the height of the fuel tank. Our firewall exceeds the rules by a couple inches and, well, every inch counts when you are talking about fuel.

With fairly think metal on hand we decided to add some stiffness to the firewall by using the bead roller.

The final firewall weighs close to nothing, is sealed, but also stiff and doesn’t appear to rattle. The panels look pretty nice as well! (of course this is probably the only time anyone will see them.)

We have had a number of late nights at the shop recently and we are making some great progress. In the next week we should be able to have the car back together and head down to do some suspension tuning with our new weight distribution.

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