Belgian GP driver fuel load predictions

Posted on | Author Keith Collantine

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)