I agree with everyone trying to argue that pit stops are not making or breaking your race, but I also see the fun in trying to make pit stops more efficient. It's nice to have them go quick just to avoid standing in the sun holding up that 5 gallon jug for a few extra minutes.
A few general notes. The Hunsaker jugs are the easy button. They aren't blisteringly fast as purchased, but some simple changes to the flexible hose will make them very quick. Practice to make sure you can stop fueling before you overfill. I tried modifying other fuel jugs, and ignoring that modified tanks are technically against the letter of the rules, they worked but required constant upkeep and repair. We bought Hunsaker jugs finally so we wouldn't have to think about them ever again.
Ideally you want the air vent feeding the bottom of the jug so that when you have it upside down the air is just cleanly flowing into the headspace, not having to bubble through all the fuel. That's why the Hunsaker jugs mold the vent down the side the way they do. You want a large air vent, but more importantly you want the air vent balanced to the fuel outlet. An oversized vent does no good if the outlet is your bottleneck.
Side musings. I wish the tuffjug ripper caps were faster. (https://www.tuffjug.com/products/ripper-caps.html). They make it impossible to overfill (if your setup has the jug fully upsidedown and stuck into your filler) because the air vent is built into the dump, so once the fuel level reaches the cap it just stops flowing. I love them with our fuel cell, but they are slow. Like at least a minute to dump each one. Now we tend to dump on average 2 Hunsaker jugs and then use a tuffjug to let us fill top the top without spilling a drop.
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