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Thread: Pit Stop Fuel to End of Race is not fueling enough (IMSA Race)

  1. #11
    VP PR Manager Sparten's Avatar
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    We are going to make some changes to this calculation in the next update, so instead of setting a fixed amount of liters or gallons in
    "Additional fuel to add to finish the race"
    it will be "Additional fuel to add to finish the race (number of laps worth)", the value can be in both whole or fractions of a lap(s).
    "Enable tight fuel calculations" will be removed but setting another value then "0" to
    "Additional fuel to add to finish the race (number of laps worth)" will have the same effect as having it enabled.

  2. #12
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    Please fix this asap. I just went from 7th place to last place on the second or third last lap because crew chief didn't give me enough fuel. IMSA, Porsche, Watkins.

  3. #13
    Crew Chief Mega Corp CEO mr_belowski's Avatar
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    this is very puzzling. The fuel calculation code does have some issues in the current live build but these are (mostly) accumulating rounding errors that happen because we're rounding the intermediate calculations 'up'. So this means the current fuel code is usually over-filling, not under-filling.

    One possibility is changing average fuel use. The fuel calculation is based on your recent laps consumption. So if you're fuel saving as you reach your pitstop, the app will assume your fuel use over the last few laps is an accurate reflection of your fuel use for the remainder of the race, and so will under-fuel in these circumstances. I'll have a think about it

    [edit]

    i'm making a bit of an assumption here but as i can't see what else could have caused this, i've changed the 'auto refuelling' calculation to use the overall session average consumption rather than the recent average consumption. This will be in the next release

  4. #14
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    How about adding a voice option "Chief... restart fuel calculation" or "pitstop add fuel use last laps" and "pitstop add fuel race average"

    You get my drift..Something like this

  5. #15
    can you make CC just take your 3 highest fuel usage laps? say like lap 3, lap 9 and lap 14 are your highest used fuel, can it not take them 3 to calculate the needed fuel? in iracing its very common for ppl to lift and coast to save fuel, especially the closer you get to a pit stop, taking the 3 highest instead of the 3 most recent laps would solve this

  6. #16
    I don't think they need to change too much, been using it for 6 months and have never fallen short of fuel. I always use litres!

  7. #17
    I had issues with CC v4.9.5.7 under-filling fuel during Pro Mazda at Watkins Glen races last week. These 40 minute races only needed an extra 3-5 liters of fuel to finish.

    The majority of the time it worked okay if I pitted late in the race (i.e. lap 18 of 22), but if I decided to do my fuel stop early (i.e. lap 4 or 5) it would pretty much always under-fill. This was unfortunate as it really limited my pit stop strategy.

    Note, this was even with the "Additional fuel to add to finish the race" set to 1.
    Last edited by Scott McIntyre; 05-11-2018 at 14:22.

  8. #18
    Crew Chief Mega Corp CEO mr_belowski's Avatar
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    I'm speculating here, but this might be due to the opening lap(s) having lower fuel consumption than later laps - standing (or rolling) start, slowing down for traffic, more drafting, etc. So the average consumption figure at this point is not necessarily an accurate reflection of the average consumption for the whole race. It's a tricky one to get right. I'll have a think about it, but as the app can't really know the impact of track conditions on fuel consumption I might just have to add an additional 5% or something to the consumption calculation if it's in the first 3 or 4 laps of the race.

    Another compounding factor is that small errors will be greatly amplified by the relatively small amount of fuel you're adding - if the app is short by just 1 litre, that's one quarter of the total amount it should be adding.

    If you pit in the middle of the race do you get the right amount of fuel?

  9. #19
    Crew Chief Mega Corp CEO mr_belowski's Avatar
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    OK, slight change of plan.

    The app collects the fuel consumption for each lap. Normally, we'd use the overall average of these per-lap consumption values, discarding the first lap. In cases where we want to calculate fuel and have plenty of per-lap consumption values, this makes sense (the lap-to-lap variability will tend to cancel out). In cases where we have few per-lap consumption values (like in your example - pitting on lap 4 or 5), then the lap-to-lap variability will (potentially) have a big impact on the consumption average. So if the number of per-lap consumption figures is low (<5) it's probably safer to take the max consumption figure in that set, rather than the average.

    The risk here is that you have a lap that's got very high consumption (a big 'off' followed by digging yourself out of the gravel, for example). Not much we can do here - the app will over-fill. But it's better than under-filling I think

  10. #20
    Crew Chief Mega Corp CEO mr_belowski's Avatar
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    today's release has this change - if there isn't much historic consumption data the app bases its estimates on the highest per-lap fuel consumption. Hope it improves things

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