Time spent refueling a car during pit stops at an endurance race can really make the difference between winning a race and losing it. As an example, one car may be behind by a second per lap of a faster competitor on a race track. During a three hour race that may equate to 45 laps completed equaling 45 seconds of differential time. I’ve seen slower cars make up that time during refueling with a pit stop that is 50 seconds quicker than their competitor and come back to win the race by five seconds. Think of the old fable The Tortoise and the Hare. It turns out he tortoise had better flowing fuel jugs.
In endurance racing for the E0, E1, E2 and E3 classes NASA regulations mandate only 10 gallons may be added to a car from two separate 5-gallon “approved” fuel jugs. The trick to making these jugs work fast is a larger vent to allow air into the jug as the fuel empties. NASA allows fuel jugs to be modified to vent more effectively which can make things flow a lot faster. If you have ever had the pleasure of holding up a “stock” 5-gallon fuel jug and trying to fuel a car utilizing the jug’s teeny tiny little provided air vent (which is about the size of an iPod headphone jack) you know the back pain involved. Your back hurts because five gallons of fuel is heavy and it may take three to four minutes for the fuel to vacate the jug. Three minutes is forever and remember you still have another fuel jug to empty into the car. Sitting in the pits for six minutes to get 10 gallons of fuel is ridiculous and is no way to win an endurance race.
I haven’t found a commercially available NASA approved fuel jug which is set up to vent properly and get fuel into a car quickly. In order to make your pit stops fast you will need to modify some jugs yourself with a trip to your local hardware store. Walking through the paddock during the 25 Hours of Thunderhill you can see lots of teams have tried many different and creative ways of modifying their jugs to vent/fill as fast as possible. Some ideas work great, some have failed miserably.
Here is how we modified our jugs and they have proven to work flawlessly earning both a WERC championship and a podium finish at the 25 Hours of Thunderhill. All that you will need to build a set of these fuel jugs (which can empty 5 gallons in 25 seconds) is: a NASA approved 5-gallon fuel jug, some clear tubing, some zip ties, some heater hose clamps, lots of sprinkler pipe fittings and some 3M automotive epoxy.
First let’s start with the fill tube. You want the inner diameter of this to be as large as possible while having the outside diameter be able to fit inside your fuel system. Stock tanks with fuel neck restrictors will use a much smaller tube (and be slower) than a fuel cell which can allow for a much larger (and much faster) tube. Once you have the size figured out you will want to drill the cap of the fuel jug and epoxy in the largest tube possible. We used a thin walled piece of pipe, epoxied it into the cap, and then slipped our fill tube over that pipe and used a hose clamp to secure the tubing.
Large diameter tubes are great for flow, but there will be zero flow until there is proper venting. You can completely ignore the small stock vent on the jug (in fact some vents aren’t perforated from the manufacturer –don’t punch a hole through it, you will want this part of the jug NOT to leak once the jug is inverted for a fast fill). To make your own larger vent drill a hole in the jug just above the fuel level (when exactly 5 gallons of fuel is in the jug). Then epoxy in an elbow and attach some clear tubing to that elbow which will extend down to the bottom of the jug (now you can see why it is important the elbow is drilled above the fuel level –if not the fuel would leak right out). On the interior of the jug extend the outer vent tube (through the elbow you just epoxied to the jug) with some hose or a ridged pipe directed to the bottom of the jug. This is the part of the jug where the air pocket will be once the jug is held upside down during refueling.
You will need to cap the fill tube and the large vent tube of your modified jugs pursuant to NASA regulations when the jugs are not being used (this is also good practice to avoid fuel spills in your pits). Also based on NASA regulations you will need to have the words “gasoline” or “fuel” on the jugs along with your race car number. Simple die-cut decals work great for this.
To use the new jugs, ensure your pit crew is wearing the proper safety equipment (equivalent to a driver minus the HANS device) and you have a fire extinguisher person ready (at a location 7 feet away from the car’s filler neck). Hold the handle of the fuel jug with the left hand, ensure the vent tube is on THE TOP SIDE of the jug as it is raised into the air with the right hand on the bottom of the fuel jug. It helps to have another fueler “mate the bull to the cow” and insert the fill tube from the fuel jug into the gas tank (or fuel cell) filler neck. Invert the jug, keeping the vent tube on the upper side, and watch the fuel pour smoothly and swiftly into the tank. Twenty-five seconds later and you’re ready to fill with your second jug and then let the car hit the track (ahead of your competition).
Like any pit stop maneuver, practice makes perfect and we have found that even with these tricked out jugs, it is best to have three people run the fuel team: one as the jug lifter, one for nozzle placement, and one for the fire extinguisher. And with a fresh tank of gas and hour left in the race all that’s left to do is win!