Belgian GP driver fuel load predictions

Lewis Hamilton is first on the grid but will he also be first into the pits for fuel?

Lewis Hamilton is first on the grid but will he also be first into the pits for fuel?

Fuel strategy is enormously (and wearisomely) important in deciding the outcome of races. So when will Lewis Hamilton, Felipe Massa and the rest of the top ten have to make their first stops for fuel tomorrow?

During the qualifying live blog Bert did a quick comparison of the increases in lap times between Q2 and Q3 for the top ten drivers so get an impression of who had added the most fuel ahead of Q3.

I thought that was a smart way of tackling the problem, so I’ve applied the approach to the top ten drivers and compared it to last year’s pit stops to try to figure out who’s light and who’s heavy:

Differences between Q2 and Q3 lap times for the top ten qualifiers

2008 Belgian Grand Prix top ten qualifiers Q3 lap time increases compared to Q2 (click to enlarge)

2008 Belgian Grand Prix top ten qualifiers Q3 lap time increases compared to Q2 (click to enlarge)

In Q2 drivers typically qualify with the bare minimum of fuel. In Q3 they add their race fuel loads. The increase in lap time this causes gives an indication how much fuel they are carrying for tomorrow’s race. This graph shows how big that delay is for each of the top ten qualifiers.

Some drivers only made one attempt at a flying lap in Q2, others put on fresh tyres to have a second go later in the session. These drivers who did extra laps may have benefited from better track conditions later in the session which helped them improve their times.

Therefore, the difference between their Q2 and Q3 times may be slightly higher. These drivers are Robert Kubica, Fernando Alonso, Mark Webber, Sebastien Bourdais and Sebastian Vettel.

When the top ten pitted at Spa in 2007

For comparison, here are last year’s top ten qualifiers and when they made their first pit stops:

Position Driver Lap of first pit stop
1 Kimi Raikkonen 15
2 Felipe Massa 16
3 Fernando Alonso 15
4 Lewis Hamilton 16
5 Robert Kubica* 15
6 Nico Rosberg 14
7 Nick Heidfeld 18
8 Mark Webber 14
9 Jarno Trulli 14
10 Heikki Kovalainen 22

*Started 14th due to an engine change penalty

2007 Belgian GP qualifying report

Spa fuel predictions for 2008

So what can this data tell us about the different fuel loads for the drivers in the top ten?

Lewis Hamilton and Felipe Massa are very likely fuelled lighter than their respective team mates, which fits with the pattern seen in recent races. Because a lap of Spa is so long, the teams have more time to ready themselves between each pit stop, so the difference in fuel load is likely no more than a lap.

As the differences between Q3 and Q2 times this year for the top drivers is around four to five tenths higher than last year, it seems the drivers are set for slightly longer first stints. This could be the teams hedging their bets due to the possibility of rain tomorrow.

It seems a good bet that the high-qualifying McLarens and Ferraris are fuelled to lap 16 (Hamilton and Massa), while Heikki Kovalainen and Kimi Raikkonen will go to lap 17. (Unless there’s some other reason why these gaps should be bigger that I’m not aware of – please post suggestions below).

Most of the other drivers will probably make their stops on the same laps or possibly a bit later. Nick Heidfeld will probably be a lap lighter than Robert Kubica (if not, Kubica is having a very poor weekend). I would expect the Fernando Alonso/Mark Webber/Robert Kubica trio to pit around lap 18, then Robert Kubica and Sebastien Bourdais on the lap after that.

It seems clear from the large difference between Vettel’s Q2 and Q3 times that he is fuelled near-full. This is a common tactic for teams who get into Q3 but don’t expect to qualifying in the top five or so. Because the cars from 11th and back can start with as much fuel as they choose, it makes sense for Toro Rosso to have at least one car heavily fuelled and accept he will start tenth.

These predictions are part-research, part-guesswork. Have I got the prediction right? Join us during tomorrow’s Grand Prix Live Blog to find out.

Please do suggest other ideas or correct my working in the comments below. One way of extending the analysis would be to look for data on what the time penalty is per lap of fuel at Spa for F1 cars – although reliable figures on this can be hard to find.

And yes, it is a crime that F1 races are usually decided by stuff as tedious as fuel strategy. I still think race-fuel qualifying is nonsense and refuelling should be banned.

List of every lap time by each driver in qualifying (PDF)

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23 comments on Belgian GP driver fuel load predictions

  1. D Winn said on 6th September 2008, 20:26

    Keith, what about the number of laps completed in Q3 – this would affect the 1st pit stop -unless the top 10 all did the same number of laps

  2. Keith Collantine (@keithcollantine) said on 6th September 2008, 20:47

    With Spa being so long I think all of them did out lap-quick lap-in lap twice, except for Vettel, so I don’t think there’s a huge difference there. Also I think for the purposes of this we want to know how much fuel they have on board for tomorrow’s race, so what we’re interested in is their fuel loads at the end of Q3, not the start.

    However I will add a PDF of all the drivers’ times for all of qualifying so you can have a look at the data for yourself…

  3. Phil B said on 6th September 2008, 20:50

    Nice approach, just to echo your comments, what a shame we need something like this to determine what really happens on Saturdays.

  4. D Winn said on 6th September 2008, 20:50

    “fuel loads at the end of Q3, not the start” – good point Keith

  5. The number of laps in really important, unless you consider tire wear. It’s the fuel load at the end of Q3 that matters. A driver can do 1 lap less and just put one less lap of fuel in the tank to compensate. The end time should be the same.

    BTW, it was not my idea. Credit goes to Bertrand Houle from RDS, a local French-Canadian broadcaster. He is an excellent statistician!

  6. Snoopy said on 6th September 2008, 22:54

    Lewis Hamilton said that he believes that ferraris (including Kimi) are lighter than he or equal. That means that MclArens are just much much faster than Ferraris or Lewis Hamilton BELIEVE that he is much much faster than anybody else with same fule loads.

    Sunday will tell…

  7. Kilwa said on 7th September 2008, 0:46

    Nice post Keith .

    I believe vettel won’t complete the first 18 Laps so your prediction is wrong :p

    Nice graphic , you don’t know if its going to rain or no , i’ve checked 3 sites and All of them predicted that no Rain for tomorrow 60% chance .

    if its going to be dry i agree , but i think Kova will be heavier than Kimi during the second pitstop

  8. Jonesracing82 said on 7th September 2008, 0:50

    yer, i for one think Ayrton senna would b turning in his grave if he knew quali is now decided on fuel loads and is pretty much the race decider these days!

  9. Unless Felipe gets Lewis at Turn 1, This race is in Lewis’s bag.

  10. John Beamer said on 7th September 2008, 6:48

    Important when you do this Keith to account for the fact that Lewis was on the prime tyre in Q2 ….

  11. Keith,

    I make this kind of analysis for each race this year, and despite is very difficult to predict exactly the number of laps for the first pit stop, it will give you an idea of teams/drivers strategy for the first stint of the race.

    As my English is not good enough, I’ll try to explain to you what I’m doing just taking the example of this Race Spa, it’s easier for me that way (I hope to write it properly enough to make me understand by all of you!)
    SPA:

    Effect of 10 Kg of fuel on lap times: 0,48
    Estimated fuel burned by lap: 3,5 Kg

    So, one lap of fuel means 0,168 Seconds in lap time

    (I take this information from F1world web page, but there should be several websites providing this statistics information)

    Then I take Lap differences between Q2 and Q3 and transform it in number of laps. Ie: Lewis time differences were 1,250 Seconds. So, this will mean 7,4 additional laps respecting Q2. (1,250/0,168).

    Then I adjust number of laps difference between Q2 and Q3. Lewis did 3 laps in Q2 and 6 laps in Q3, so, time differences include 3 additional laps.

    So, Lewis will have extra fuel for 4,4 laps respect Q2 (7,4-3=4,4).

    As have been declared by some teams and drivers, they put fuel for more less 10 laps in Q2.

    So with this calculation Lewis will pit in lap 14 or 15. (10+4,4)

    Doing the same for the first 8 drivers, those are the estimated first pit stop:
    Lewis: 14
    Felipe: 15
    Heikki: 18
    Kimi: 17
    Heidfeld: 23
    Alonso: 22
    Webber: 21
    Kubica: 24
    Bourdais 24
    Vettel: 34

    This is a theoretical exercise and there are other many factors that could affect as: driver errors, tyres, track temperature… but give me a good idea of how drivers have performed in comparison with their team mates, and race strategy.

    For this case, some conclusions come to my mind:

    McLaren have performed very well in this track, better than expected. Massa time difference respect L Hamilton is 0,34 Secs. And the time advantage for one fuel lap is 0,168 Secs. So Felipe could never take the time of Lewis for the Pole. Kimi has achieved P4, despite he has 1 lap less fuel than Kovalainen.

    Heikki Kovalainen has had to renounce a possible pole in favour of L Hamilton (as in some other races) For this reason I guess the guy didn’t look so happy in the press conference after the race.

    Sebastian Vettel is in One Stop Strategy for sure.

    Finally, I assumed 10 laps of fuel in Q2 for this race. I think they should have less fuel according lap times (1,8 min per lap aprox.) So my guess is they will be doing the first pit stop one or two laps before my estimations.

    I hope this have been useful for you, and sorry for my rudimentary (to put it mildly) English knowledge.

    If some of you could add some complementary ideas or corrections to my calculations, will be so much appreciated.

  12. Keith Collantine (@keithcollantine) said on 7th September 2008, 9:16

    IDR – thanks for that – much more comprehensive than my approach! Four laps difference between the McLaren drivers would be surprisingly large, but I see elsewhere Ron Dennis has hinted Hamilton could be light.

    Of course, if we get wet weather or a safety car period today it could spoil our predictions completely!

  13. igor87 said on 7th September 2008, 9:16

    ^^ true. So in reality Lewis’ lap time difference should be slightly bigger still.

  14. diseased rat said on 7th September 2008, 9:27

    Awesome analysis IDR, many thanks.

  15. Juan H said on 7th September 2008, 9:59

    De la Rosa in Spanish TV Tele5 always comments that is a mistake to go too light of fuel; one could say the same about going too heavy (without SC interfering)… but at the end…one never knows!

    The battle is settled between Lewis and Felipe for winning this race; somehow I feel sad for Kimi and Heikki, they seem to play secondary roles…and what to say on Fernando? sadness is even greater!

    Looking forward to an exciting race.

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