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Thread: Fuel Algorithm Off?

  1. #1
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    Fuel Algorithm Off?

    21 laps to go, got fuel, entered last lap in 1st place, ran out of fuel on the backstretch, coasted across in 11th.

    Indy oval in the Dallara IR-18.

    I have 'base fuel calculations on max fuel consumption' checked, and add an additional half lap of fuel to finish the race. Most of the first 29 laps were run in clean air, so fuel consumption/lap should have been higher then, and I had no damage. I suppose it's possible that the temperature or wind speed changed, but I heard of this happen to another person as well.

    It was what I would consider a very "routine" race, with nothing unusual occurring. We had 5 yelllows in the first half, 2 yellows in 2nd half of the 50-lap race.

    Is it possible that the fuel algorithm is off on the IndyCar, or doesn't account for some other routine factor or jitter?

    I guess the obvious answer is to add an extra 10 laps of fuel on refuels just to be safe.

    This is all just FYI. In case you get more reports and notice a pattern.

    Even though it cost me a win, I still love the program and appreciate the fact that you give it to us. Thank you.
    Last edited by Rex Seattle; 02-08-2022 at 05:59 AM.

  2. #2
    Which sim? Do you have the log file? (I think fuel logging is on by default)

  3. #3
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    iRacing. Indy Fixed. Last week was Indianapolis Motor Speedway, and I refueled with 21 laps left in the race.

    Do you mean the iRacing or Crew Chief log? Assuming Crew Chief ... looking ...

  4. #4
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    Apr 2020
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    Log File from Race

    Found it. Fuel ran out on lap 50 of 50. I coasted super-slow until I got across the finish line. Most people had logged out by the time I rolled across at something like 5 Mph.

    P.S. It looks like I was mistaken, I entered the last lap in 2nd place not 1st though I swear the leader pitted before the lap started. I was biding my time behind a few cars that I knew would have to pit before race end.


    seattlerex_indy_fuel_starvation_lap_50.zip

    It looks like line 3639 is where the Pit Stop begins.

    HTML Code:
    21:55:20.804 : Playing sounds, events: mandatory_pit_stops/watch_your_pit_speed, COMPOUND_mandatory_pit_stops/pit_speed_limit
    21:55:20.804 : (mandatory_pit_stops/watch_your_pit_speed)
    21:55:22.224 : (mandatory_pit_stops/pit_speed_limit, numbers/97, frozen_order/kilometres_per_hour)
    21:55:22.994 : Fuel: Use per lap = 2.2 laps to go = 20 current fuel = 4.8 additional fuel needed = 39.7
    21:55:22.996 : Auto refuel to the end of the race, adding 40 liters of fuel
    21:55:22.996 : Cmnt: Entered pit lane
    21:55:25.224 : Clip COMPOUND_pit_entry_to_box_distance_warning has expired after being queued for 2216 milliseconds
    21:55:25.224 : Playing sounds, events: acknowledge/fuel_to_end
    21:55:25.224 : (acknowledge/fuel_to_end)
    21:55:25.224 : Taking a breath
    21:55:36.839 : Purging regular queue
    21:55:36.839 : Purging immediate queue
    21:55:36.839 : removed 0 messages from the queues before triggering pit countdown
    21:55:36.839 : BOX IN 5 at 135.6024
    21:55:36.839 : Playing sounds, events: COMPOUND_pit_time_countdown_5
    21:55:36.839 : (mandatory_pit_stops/box_in, numbers/5)
    21:55:37.735 : Laps completed = 30
    21:55:37.735 : Time elapsed = 32:09.950 (1929.950)
    21:55:37.735 : Overall Position = 10
    21:55:37.735 : Class Position = 10
    21:55:37.735 : Session phase = Green
    21:55:37.735 : Laptime: 00:56.113,  Valid = True
    21:55:37.735 : Fuel: Fuel use per lap: windowed calc=2.085, max per lap=2.198 fuel(liters) left=4.300
    21:55:37.735 : Fuel: 1 laps fuel left, starting fuel = 67.404, current fuel = 4.300, usage per lap = 2.198
    21:55:37.735 : -------------------------
    21:55:37.735 : Lap 31 sector 1 tyre temps, Outer, middle, inner  |------|  inner, middle, outer
    Last edited by Rex Seattle; 02-08-2022 at 06:01 AM.

  5. #5
    Junior Member
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    Apr 2020
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    One more thing, there were a couple of other factors that could have played into it:

    1) The first half of the race had more cautions than the second half.

    2) When a car is refueled, it uses more fuel because it's heavier. The extra 40 liters was an extra 63 pounds.

    3) Since there were fewer cautions in the second half, I assume tire wear was higher, giving me less MPG.

    I dunno, I'm just throwing out guesses. I *almost* made it. It starved just a couple seconds after clearing turn #2.

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