While you haven’t heard from Project SC300 in a minute, it hasn’t been entirely idle. We took the car out to Carolina Motorsports Park last November for some additional testing and sorting, and you can see some of those results here:
One thing that we had been sitting on for a while, though, was giving ourselves the easy ability to pump out the fuel cell. We still use 93 octane pump gasoline on the SC300, and it’s not a great idea to leave that stuff sitting around in the fuel cell. Additionally, the fuel cell bladder needs to be recertified every few years, and the foam should also be replaced.
On top of that, fuel isn’t weightless. When you are dealing with power-to-weight classes (like NASA Super Touring and others), or when you have to make race weight for some other reason (spec classes, pro racing, etc.), every ounce needs to be accounted for. Rolling across the finish like 3lbs light is grounds for disqualification. You can “tune” the weight of the car by adjusting the starting fuel load, assuming you know the fuel consumption rate (for example, 3L/minute) and how long the car will be running (30-minute sprint race). Ideally, you would finish the race with zero fuel and exactly at race weight.
Figuring out fuel consumption, exactly filling the fuel cell to the right weight of fuel, and many other activities all require frequent emptying of the cell. Who wants to deal with dribbly fuel every time you swap fittings around? For sure, not me. Radium Engineering comes to the rescue with an inexpensive dry break fitting that helps get the job done cleanly — pun intended.
We decided to install the Radium dry break fitting into the return line of the fuel system. There is some debate regarding whether a fuel pump should pump through a regulator (restricted) or pump freely. If you think it doesn’t matter, you could just as easily plumb onto the supply side and not the return side. Or, better yet, just buy two and put one dry break on each line.
From the existing return line’s -6AN fitting, we would directly attach one side of the -6AN Radium dry break. We would then make a short hose to go from the other side of the dry break, through a -6AN straight fitting, to another 90-degree -6AN fitting, and onto the fuel cell’s fitting. This short hose would stay in place during vehicle operation.
Then, we got an additional half of a dry break connector and attached it to a simple -6AN hose barb fitting. We could then attach a length of regular everyday fuel hose to this barb, and the assembly would serve as our pump-out line.
Let’s get started!
Since we had a diagram, it was easy to figure out what to order! We had a sufficient length of fuel hose laying around from when we first installed the fuel cell (you keep everything like a packrat, don’t you?). A quick trip to the local parts store produced sufficient standard fuel hose.
The easy pump-out line would come first.