how to get even more accurate fuel

[fommil]

To have crewchief take over fuelling, make sure you disable autofuelling in iRacing and then enable the CrewChief property Enable iRacing auto refuelling when entering pit in race. This will send a fuel command macro to iRacing at the moment you enter the pitlane, or use the voice command "pitstop fuel to the end" to manually trigger the command to be sent to the pit crew at any time you want.

The fuel calculation in CrewChief is pretty good at estimating how many full laps are in an iRacing time based race, including for multiclass. However, keep in mind that estimating laps remaining for multiclass is really difficult due to track positioning relative to the faster class, so CrewChief will always err on the side of caution and make sure you finish the race. There's a few things you can do to make sure you don't end up with more than you needed if you want to be competitive in pitlane.

Have a look in the CrewChief Properties, and make sure they align with your personal risk tolerance, copied here for convenience. These are extremely conservative, if you want to have a riskier strategy you might want to first look at reducing the percentile in increments of 10, and halving all the "extra laps" values.

• Fuel: percentile A value of 50 will always use the median green flag fuel consumption when estimating fuel use. A value of 100 always uses the max green flag consumption. Can be set to anything in between to find a nice safety margin that works for you personally. There are road and oval variants of this setting.
• Fuel: extra laps (short tracks) Add this many extra laps of fuel for short tracks (less than 1.5 mile / 2.4 km).
• Fuel: extra laps (medium tracks) Add this many extra laps of fuel for medium tracks (1.5 to 6.2 miles / 2.4 to 10 km).
• Fuel: extra laps (long tracks) Add this many extra laps of fuel for long tracks (more than 6.2 miles / 10 km).
• Fuel: extra laps (oval tracks) Add this many extra laps of fuel for ovals in addition to the reserve, to account for potential green / white / chequered scenarios. Set to 0 if you prefer to roll the dice!.
• Fuel: extra laps (endurance races) Add this many extra laps of fuel for road endurance races (60+ minutes, tracks less than 10km) in addition to the reserve, to account for errors in race length predictions due to unexpected leader pitstops and incidents.
• Fuel: saving target (percentage) How much fuel do you think you can reasonably save? This is skill dependent and is a percentage of your remaining tank. When asked about the fuel status, the chief will note that we might not get to the end or we may need to fuel save if it falls within this amount.
• Report fuel as laps left in timed races Report how many laps left in timed races rather than how long it will last. Even if this is unset, fuel will be reported in laps near the end of the stint.
• Fuel: multiclass pitstop times (Experimental) When estimating the laps remaining in the race, treat the leader as if their pitstop will be the same length as ours. If this is disabled, we assume they do not stop and therefore we may over-estimate the laps (safer).

Log Data

Another thing you can do is PRACTICE. The more you race, and the more green laps you do in test sessions (coming back into the pits at the end of them), the more data gets put into your fuel_and_laps.json file. If you are expecting specific weather conditions, make sure to do laps in those exact conditions as well... dry and wet laps have very different fuel consumption characteristics.

Record Pit Benchmarks

Bind the voice command "time this stop" to a button and make sure you use it in your practice sessions. Either do a stop and go, or use roughly the amount of fuel you expect to use in the race (you can record multiple data points, for different series or endurance racing with full tanks). This will be saved to pit_benchmarks.json so that your crewchief knows how much time a pitstop will cost in the race. That has two benefits: firstly it will be deducted from the race time, which can mean one less lap of fuel in some situations. Secondly, it means he can give you pit exit estimates when he tells you about the pit window being open... that lets you know if stopping early would let you exit into clean air. You can also bind the voice command "where will i be after a stop" to get this information any time you want.

Be careful not to benchmark full tank pitstops, or pitstops to repair damage, if you're planning to run shorter form sprint races. If you do that, make sure you also do a stop and go or low fuel pitstop more representative of your series, otherwise you might end up not having enough fuel to get to the end. Remember, your CrewChief will take that time away from the race length.

Basically, the more prep you put into training pitstops with your CrewChief, the more accurate your stops will be, without even having the think about it.

During the Race

Your crewchief will keep you informed about your fuel, hopefully not spamming or worrying you too much (that is improving with each release). If he tells you that you need to fuel save, listen to him!

You can always ask for a fuel report by binding a voice command or button to "how's my fuel" or just get the raw numbers with "how much fuel to the end", "what's my fuel level" and "what's my fuel usage".

You can also dynamically change your safety margins by using voice commands:

- "use a risky fuel strategy" will half all reserves and reduce the percentile by 25. This is ideal if you plan to fuel save for the remainder of the race and plan on undercutting opponents by having the shortest possible pit stop.
- "use a safe fuel strategy" will double all reserves and increase the percentile by 25. This is useful if you have been aggressively fuel saving but plan on going flat out at the end.
- "reset the fuel strategy" goes back to the values in the Properties tab.

Known Issues

If bad data gets into your fuel_and_laps.json or session, it will pollute the results. In particular be aware that there's no way for CrewChief to tell if you just decided to rev the engine in the wrong gear for the lap, parked it on the apex and went to the toilet, or used Active Reset. Best just tow to the garage if you do any of that, and check or delete your JSON file regularly if you're into that kind of thing.

Always have a backup

Always have a backup plan incase your crewchief screws up. He'll be quite vocal about how much he wants to add, and you'll see how much he is telling the refueller with his macro command on pit entry. Be prepared to reach for your mouse to modify it in the pit lane.

Even the greats ran out of fuel on their last lap, nobody is perfect, not even Jim.

Asking for Help

If you read this far and CrewChief still messed up your pitstop, feel free to upload your debug logs to the iracing channel in the discord along with a description of what happened vs what you expected to happen. You can find them by clicking on "Problems? => send a saved log file to devs". Even better if you record a trace (they can be very big so you'll need to upload them to a cloud drive to share them)

[Seven Smiles]

The same is true of the other games that allow Crew Chief to change the fuel level - RF2, R3E, ACC.