I personally tend to be right down the middle, which basically means I can’t make up my mind. Races that end with cars making a fuel stop with two laps to go can make for a two things in the same race: dullness and excitement. Wow, that’s deep, huh? I understand folks who get fed up with watching the race leaders, who’ve driven to the front over the course of four hundred or five hundred miles of hard racing, have to peel off and hand over their position and points to back markers. On the other hand, being an unlettered nerd at heart, I find the science and engineering that starts at the finish of the last race, and goes to the finish of this race, to be just absolutely fascinating. If all you desire from life as a race fan is a strong run by Jr., and lots of beer, then you probably detest them, and I won’t mock you, because I’ve been on that side of the fence, too.
With all that verbiage out of the way, here are two good recent articles about fuel mileage. First up is Dr. Diandra Leslie-Pelec, who is now blogging at Building Speed (she wrote a book, too): The Math of Fuel Mileage:
Before each pit stop, the team weighs each one of the gas cans. Let’s say one of them weighs 96 lbs. The car comes in to pit, they add fuel and then weigh each gas can again. Let’s say that the can weighs 36 lbs after a stop. The change in weight is 96 lbs – 36 lbs = 60 lbs. At 6 lbs per gallon, you can infer that the can is missing 10 gallons.
Note that I very carefully said ‘the gas can is missing 10 gallons’ because we have no assurance that all 10 gallons went into the car. You’ve seen gasoline spill out everywhere when the gasman pulls the dry break away from the fuel cell inlet. That happens even more with the new dry breaks because they are a little trickier to put in place and pull out than the old gas cans were.
The crew chief looks down and makes a mental estimate of how much fuel is spilled, converts the masses from the cans into gallons and comes up with a number for how much fuel he thinks is in the car. From that, he estimates how many laps they can run. If you want to see a frustrated crew chief, look for the gas man with the raised eyebrows and the shrugging shoulders. He thinks he got it full… but he’s not sure. That’s actually sometimes worse than the one who knows he didn’t get it full. Sometimes it’s better to know the answer, even if it’s bad, than to be unsure. The scales in the pits have at least one decimal place, and my friend Josh (a member of the ex-Elliott crew chief club) suggests that the better teams have almost certainly moved to scales with two decimal places.
Next up is NASCAR Insiders’ Fuel Mileage, Fuel Mileage, Fuel Mileage:
Love it or hate it, fuel strategy is going to continue being the name of the game over the next few weeks. The last two Cup races and the most recent Nationwide Series race were all decided on late race fuel gambles, and the next three Cup races are all at tracks conducive to fuel mileage races.
If this weekend’s race turns into a fuel-mileage race, at least you’ve now got a little bit of information with which to impress your bar-stool pit crew. Use it with caution, my friends.