Stint Calculator (Google Sheets)

Giovaneveterano

1000RPM
Original poster
Feb 17, 2013
1,792
857
Hi boys! I created a spreadsheet using Google Sheets that calculates the optimum race strategy according to fuel levels and tyre wear. It's not black magic, but it requires a tiny bit of time to fully understand it. I just feel like I have to share my work with you as I love this community.
You can get it from this link:

Copy into your Google Drive
The first and the most important step you have to take it’s to make sure you’re not editing the public release of the sheet. Other people may be online working on the same file at once and get in the way of each other. By copying the Google Sheet on your Drive, you’re sure no one else can edit it. You can still view and edit the sheet even if you haven’t a Google Account, but I highly recommend avoiding it.

Copy into your Google Drive by: File > Create a copy

Items Description
The whole interface is divided into 4 different tabs: Race, Fuel, Tyres and Pitboard; with a total of 7 editable cells, each of these highlighted with a small black triangle in the upper-right corner.
A brief explanation of each cell is shown by hovering the mouse over it and it’s reported here for clarification purposes.

RACE
  • Race Length: in minutes. The software can calculate the strategy for VERY long races, but only the first 150 laps are shown, as the Pitboard repeats itself at some point.
  • Laptime: in seconds. Expected average laptime in race conditions. Use comma as a decimal separator.
  • Estimated Laps: the total amount of laps are estimated based on your average race pace and the race length. The white flag is supposed to be shown only when there is no time left.
FUEL
  • Tank Size: tank capacity, or your starting fuel, if you don't need to stop for refueling.
  • Fuel/Lap: amount of fuel consumed every lap. It can be set in Litres, kg or Gallons. Use comma as a decimal separator.
  • Fuel Window: In this fuel window, the number of refuels doesn't change. A consumption lower than that means less pit-stops, more otherwise.
TYRES
  • Tyre Wear: you can enable or disable tyre wear by using this toggle.
  • Wear/Lap: the amount of tread used per lap. It can be an average value on 4 wheels or the lowest one, based on your personal taste.
  • Strategy: aggressive strategy tends to change tyres more often, while Conservative keeps them on longer. Normal is in between.
PITBOARD
  • Lap: the calculations predicted that you’ll need to box at the end of this lap.
  • Elapsed Time: the elapsed time from the beginning of the race when you stop. Useful to plan driver’s swaps during endurance races.
  • n° of pits: the total amount of pits predicted to complete the race, even if the pitboard can only show the first seven pit-stops.

userinterface.png
 
Last edited:

Giovaneveterano

1000RPM
Original poster
Feb 17, 2013
1,792
857
I added an "ISSUE SOLVER" section where the software check for any strange value you put in and suggest a solution.
 
Last edited:

Giovaneveterano

1000RPM
Original poster
Feb 17, 2013
1,792
857
Updated:
  • Now strategy calculator works up to 500 laps.
  • Removed "worn tread" value.
  • Using kg instead of Gal.
  • Other small fixes.
 

Giovaneveterano

1000RPM
Original poster
Feb 17, 2013
1,792
857
I'm trying to implement pit window and max driver stint lenght, but it's pretty hard atm.
If anyone is a black belt in Excel let me know how to do it, I appreciate any idea.
 

Giovaneveterano

1000RPM
Original poster
Feb 17, 2013
1,792
857
Updated with the latest scrip.
The latest version should manage a complete separate tyre and fuel strategy.
It still has the big limit of scheluded pitstop, but I'm working on it.
Cheers.
 

Y22 Rydr

1RPM
Jul 19, 2017
5
6
45
I'm trying to implement pit window and max driver stint lenght, but it's pretty hard atm.
If anyone is a black belt in Excel let me know how to do it, I appreciate any idea.
For driver stints I record my best lap time in minutes and seconds (i.e. 1:49) and I assume the earliest pit would occur at 60 minutes and the latest at 65 minutes. I then use the following equations for driver stints:

60÷(lap time minutes+(lap time seconds÷60))

60÷(1+(49÷60))=33 laps

65÷(lap time minutes+(lap time seconds÷60))

65÷(1+(49÷60))=36 laps
 

LeSunTzu

1000RPM
Feb 13, 2013
1,197
2,068
The calculation of necessary fuel is too tight, you should factor in several things:
- the fuel burn in formation lap;
- some margin if somebody does a lap more than you antipate;
- you start losing fuel pressure before the tank goes to 0;
- in a race you might burn a bit more fuel than in practice if you are in the middle of a long fight.

Also fuel burn depends on the ECU map, you should include the option. That is an important "strategic" option for long races.
 
Last edited:

Giovaneveterano

1000RPM
Original poster
Feb 17, 2013
1,792
857
The calculation of necessary fuel is too tight, you should factor in several things:
- the fuel burn in formation lap;
- some margin if somebody does a lap more than you antipate;
- you start losing fuel pressure before the tank goes to 0;
- in a race you might burn a bit more fuel than in practice if you are in the middle of a long fight.

Also fuel burn depends on the ECU map, you should include the option. That is an important "strategic" option for long races.
The software already keeps a 1 lap margin of fuel each stint. I agree on ECU map and I tried, but I stopped working on it because this depends on so many factors that it needs a completely new algorithm: lap time gain/loss per map setting, fuel burn on each map.
All this can be easily override by "average fuel/lap": this is your target fuel consumption, just stick with it.

Btw I'm more than happy to read any suggestion you have, I love your opinions.
 

Y22 Rydr

1RPM
Jul 19, 2017
5
6
45
If you build a drop down or add a cell then the user can choose the amount of extra fuel they want. I typically run 10% - 15% extra fuel. I prefer a bit extra fuel over the potential of running out.
 

Chaingod

1RPM
Oct 29, 2011
3
0
There is an error in the cell for "tread unit".
If I try to change from "%" to "mm" via drop down menu I get an error because the cell is protected.
Overall really nice and versatile calculator, would be nice if it were possible to mod this into an actual app for AC/ACC which reads the stint data itself.

Good work Giovaneveterano
 

Giovaneveterano

1000RPM
Original poster
Feb 17, 2013
1,792
857
I'm still working on it, fixing bugs and adding new utilities. It has been super useful for longer races, but in general as a tool for simracing.
 
Last edited:

Giovaneveterano

1000RPM
Original poster
Feb 17, 2013
1,792
857
There is an error in the cell for "tread unit".
If I try to change from "%" to "mm" via drop down menu I get an error because the cell is protected.
Overall really nice and versatile calculator, would be nice if it were possible to mod this into an actual app for AC/ACC which reads the stint data itself.

Good work Giovaneveterano
If I can find someone who can develop one I'm more than happy to contribute!