Here is a set of brand new fuel jugs built and ready to go for some fast fills and quick pit stops. You can see the vent tubes on the side of each of the jugs. They have the required car number on the sides of the jugs pursuant to NASA enduro regulations. We chose the clear/white colored jugs so it would be easier to see the fuel level during refuels. Some of the blue and red colored jugs are difficult to see the fluid inside, especially at night.

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.

NASA endurance regulations require a 5-gallon fuel jug be used to refuel cars in the E0, E1, E2, and E3 classes. Filling up cars with these fuel jugs can be very time consuming if the jugs aren’t modified. In order to get the jugs to empty quickly, a larger fill tube should be added to allow for more volume of flow. Additionally a large vent to allow air into the jug to displace the emptying fuel will expedite the fueling process.
NASA endurance regulations require a 5-gallon fuel jug be used to refuel cars in the E0, E1, E2, and E3 classes. Filling up cars with these fuel jugs can be very time consuming if the jugs aren’t modified. In order to get the jugs to empty quickly, a larger fill tube should be added to allow for more volume of flow. Additionally a large vent to allow air into the jug to displace the emptying fuel will expedite the fueling process.

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.

This is the magic stuff, 3M’s SMC/FRP 10 (part #08272). This is a 2-part automotive epoxy which is immensely strong and is not corroded by gasoline. It isn’t cheap but it works great for sealing holes in the jugs. Holes are bad, because holes mean leaks, and leaks mean spilled fuel which means penalties in the pits. Nobody wants that, the idea with these fuel jugs is to have faster pit stops, not five minute stop-and-go penalties.
This is the magic stuff, 3M’s SMC/FRP 10 (part #08272). This is a 2-part automotive epoxy which is immensely strong and is not corroded by gasoline. It isn’t cheap but it works great for sealing holes in the jugs. Holes are bad, because holes mean leaks, and leaks mean spilled fuel which means penalties in the pits. Nobody wants that, the idea with these fuel jugs is to have faster pit stops, not five minute stop-and-go penalties.

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.

This is the interior of the cap for the fuel jug. The standard fill hose was too restrictive for a car we were racing with a fuel cell so we drilled out the stock mount for the fill hose and replaced it with a larger piece of tubing. You can see here the tubing is thin walled to help with flow and it is held in place with the green 3M epoxy.
This is the interior of the cap for the fuel jug. The standard fill hose was too restrictive for a car we were racing with a fuel cell so we drilled out the stock mount for the fill hose and replaced it with a larger piece of tubing. You can see here the tubing is thin walled to help with flow and it is held in place with the green 3M epoxy.
This is the top side of the fuel jug cap. You can see the larger tubing epoxied into the cap. Then the clear fill tube is held on with a heater hose clamp. The outer diameter of this hose we chose to fit perfectly into a fuel cell.
This is the top side of the fuel jug cap. You can see the larger tubing epoxied into the cap. Then the clear fill tube is held on with a heater hose clamp. The outer diameter of this hose we chose to fit perfectly into a fuel cell.
The larger the diameter hose means the more volume of fuel you can cram through the tubing. The diameter of hose you choose is dependent on the vehicle you are fueling. A car with a fuel cell may have a much larger hole to accept a larger tube. A stock vehicle has a much smaller hole in which to insert a fuel jug hose, and thus takes longer to fill. The hose on the left has been reduced by placing a smaller hose into a larger hose and then a hose clamp was used to keep the tubes from separating. Duct tape is covering the metal hose clamp so there is no chance of spark during refueling.
The larger the diameter hose means the more volume of fuel you can cram through the tubing. The diameter of hose you choose is dependent on the vehicle you are fueling. A car with a fuel cell may have a much larger hole to accept a larger tube. A stock vehicle has a much smaller hole in which to insert a fuel jug hose, and thus takes longer to fill. The hose on the left has been reduced by placing a smaller hose into a larger hose and then a hose clamp was used to keep the tubes from separating. Duct tape is covering the metal hose clamp so there is no chance of spark during refueling.

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.

This elbow is where the vent tube goes through the jug. Its placement is key because it needs to be above the fuel level when 5 gallons of gasoline is in the jug. This way when the jug is being stored fuel will not drain out of the vent tube. You can see the 3M epoxy we used to seal the attachment point (it’s not pretty but it works). This is important because this jug will be completely inverted during fueling and you don’t want any fuel spills during a pit stop.
This elbow is where the vent tube goes through the jug. Its placement is key because it needs to be above the fuel level when 5 gallons of gasoline is in the jug. This way when the jug is being stored fuel will not drain out of the vent tube. You can see the 3M epoxy we used to seal the attachment point (it’s not pretty but it works). This is important because this jug will be completely inverted during fueling and you don’t want any fuel spills during a pit stop.
In this photo you can see the large vent tube and the enlarged fill tubes sealed with our 3M 2-part epoxy. You can also see the very small black “stock” vent hole which is closed. If you were to use the vent that came with the fuel jug to fill your car with fuel it would take about 3-4 minutes to empty the tank (and that isn’t an exaggeration).
In this photo you can see the large vent tube and the enlarged fill tubes sealed with our 3M 2-part epoxy. You can also see the very small black “stock” vent hole which is closed. If you were to use the vent that came with the fuel jug to fill your car with fuel it would take about 3-4 minutes to empty the tank (and that isn’t an exaggeration).

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.

In this shot you can see the fast fill fuel jugs in action. Everything is being done correctly, the vent tube is on top and the vent cap has been removed. There is a car number and the requisite word “GASOLINE” on the jug. Plus the fuelers are wearing the required safety equipment. This was a quick/no penalty stop during a NASA endurance race.
In this shot you can see the fast fill fuel jugs in action. Everything is being done correctly, the vent tube is on top and the vent cap has been removed. There is a car number and the requisite word “GASOLINE” on the jug. Plus the fuelers are wearing the required safety equipment. This was a quick/no penalty stop during a NASA endurance race.

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).

This is a shot of the interior of the fuel jug. This is the other end of the vent tube which goes all the way to the bottom of the fuel jug (with an angle cut as to not get blocked). This vent is placed to be in the air pocket position once the fuel jug is inverted to get the fuel out as quickly as possible. We used a small flexible hose attached to a longer plastic pipe which keeps the vent tube in the position we want. You will need small hands to get inside to tighten these clamps.
This is a shot of the interior of the fuel jug. This is the other end of the vent tube which goes all the way to the bottom of the fuel jug (with an angle cut as to not get blocked). This vent is placed to be in the air pocket position once the fuel jug is inverted to get the fuel out as quickly as possible. We used a small flexible hose attached to a longer plastic pipe which keeps the vent tube in the position we want. You will need small hands to get inside to tighten these clamps.

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!

In this photo you can see the large vent tube and the enlarged fill tubes sealed with our 3M 2-part epoxy. You can also see the very small black “stock” vent hole which is closed. If you were to use the vent that came with the fuel jug to fill your car with fuel it would take about 3-4 minutes to empty the tank (and that isn’t an exaggeration).
In this photo you can see the large vent tube and the enlarged fill tubes sealed with our 3M 2-part epoxy. You can also see the very small black “stock” vent hole which is closed. If you were to use the vent that came with the fuel jug to fill your car with fuel it would take about 3-4 minutes to empty the tank (and that isn’t an exaggeration).
 This is the bottom of the vent tube which we affixed to the fuel jug with some long zip ties and a hose clamp. You can also see in this photograph the “GASOLINE” decal which is required on the fuel jugs pursuant to NASA regulations. It is imperative this vent tube be on the high side of the jug when fueling, because if it is on the low side of the jug you will pour fuel right down your leg (I know this for a fact because I’ve done it during practice –not fun and I smelled like gas for a week).
This is the bottom of the vent tube which we affixed to the fuel jug with some long zip ties and a hose clamp. You can also see in this photograph the “GASOLINE” decal which is required on the fuel jugs pursuant to NASA regulations. It is imperative this vent tube be on the high side of the jug when fueling, because if it is on the low side of the jug you will pour fuel right down your leg (I know this for a fact because I’ve done it during practice –not fun and I smelled like gas for a week).
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Image courtesy of Rob Krider