How to Calculate Your Fuel Rate

You drove brilliantly. A podium all but guaranteed.

Then disaster strikes. There’s a problem with your fuel.

Perhaps you run out on the last lap, the finish in sight.

Maybe it’s disqualification – your racecar comes in underweight, or there isn’t enough fuel for scrutineering checks.

All your efforts, preparations, the new tyres, upgraded aero, fresh engine build – gone to waste.

Your hard-fought positions during the race, all for nothing.

As the saying goes, “To finish first, first you have to finish.”

No one wants to be that driver who gets their fuelling wrong. You want to be like Simon, who unlike his competitors, got his fuelling right – to win on the last corner of the last lap of this epic 24-hour race [link].

Yet, fuel is heavy.

Why handicap yourself by carrying more than needed?

Lighter is faster, after all. But how little are you brave enough to carry?

Fuel Rate - How brave are you with your fuel amount?
Fuel Calculator – How Brave Are You

Know Your Fuel Rate

One of the most important numbers you need to know is the fuel rate your car uses fuel – your fuel rate.

Even this is not straightforward, as you will use more fuel in normal conditions than in the wet, for example.

However, while fuel calculations can get remarkably involved (see video), I thought I would share a simple method you can use to estimate your fuel rate usage.

You can read below, or watch me explain the method in 2 minutes at the end of this explainer video for my fuel calculator:

video preview

How To Work Out Your Fuel Rate:

  • People have different preferences for fuel rate. These include litres (or gallons) per lap, per distance, per time, even per weight.
  • Each version has its pros and cons, but apart from per lap, they will broadly translate between tracks, or at least enough to give you a head start at the beginning of your event.
  • To get these values, go out and run at race pace for at least 10 laps.
  • Then come back in and measure the amount of fuel you have used.
  • You can do this by draining the fuel tank to start with, adding a known amount of fuel, then draining the tank again at the end.
  • The difference between the fuel added and fuel remaining is the amount of fuel you have used in your laps.
  • Straight away, you can calculate the amount of fuel you have used per lap, as you can divide the fuel used by the number of laps.
  • It also gives you the amount of fuel per distance, as you can divide the amount of fuel by the length of the track. (Here is a link to a database of track lengths)
  • To get the amount of fuel per time, what I do is take an average of the lap time you did on your stint.
  • Then divide the total fuel used by the average lap time to get fuel used per time (normally either per second or per minute).

If you want to run or test different conditions (such as aero mods or lift and coast strategies) on this fuel rate, then just follow the same calculation process.

Once you have a few performance models created, you can then compare their effects on your race and fuelling strategy.

Key for Endurance and Sprint Events

These fuel usage figures are useful whether you run sprint-type events or endurance events.

Clearly, the impact is greater in endurance racing, but running the minimum weight car you are allowed is also critical in competitive sprint racing.

Plus, if these calculations save you fuel, you’re saving money too!

If you are lucky enough to have a car (or sim car!) with live fuel rate data, you already have a head start for these calculations. If not, then this is how I’ve tackled it reliably.

If you give it a go, be sure to sign up to Ahead of the Curve and let me know how you get on. How much does your car vary track to track?

 

Whenever you're ready, there are 4 ways I can help you:

  1. Get 1-1 Help From Samir – Sometimes you just need an expert race engineer to get you back on track. Get your questions answered, the best approaches made clear and your goals achieved, with my support.
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