WEC-LMGTE Am: 6 Hours of Fuji 2023 analysis
by Boris Deshev, Ph.D.
The 6 Hours of Fuji saw the closest LMGTE Am race so far this season with 8 of the 13 cars remaining on the lead lap despite there being no safety car (SC) to reset the gaps between them. In the words of Anthony Davidson: “it was a bit confusing to follow that race”, and “every time I looked there was a different car in the lead”. We also saw a V8 muscle car (Corvette Racing #33) impressing everybody with its fuel economy, doing one less stop for fuel despite it being faster than all other GTE cars but one. We take a closer look at the data from the race, generously provided by FIA WEC and Al Kamel Systems, to try and understand some of the reasons behind these results.
WEC RACE ANALYSIS TOOL
Figure 1: WEC race analysis tool (WRAT). Top to bottom the separate panels show the position in class, interval in seconds between all the cars and the average lap time of the winning car and the lap times over the 6 hours. On the bottom panel, the thin lines of the corresponding color show the mean lap time. The graph is interactive. By default only the traces of the podium finishers are shown.
WHAT DETERMINED THE FINISHING ORDER
Figure 2: Factors which normally explain the finishing positions. Left to right the cars are ordered according to the cumulative effect of race pace, total pit time and post-race penalties. The right most column shows the actual final classification subject to final scrutineering.
Usually in this section we examine the effects of four separate parameters on the finishing order: race pace, pit time, SC and post-race penalties. At Fuji there was only one SC period at the very beginning of the race which had no bearing on the finishing order. The Full-Course Yellow (FCY) at the very end of the race was also very short but it did affect the finishing order (see below for details). Post-race penalties affected the finishing position of only one car – Kessel Racing’s #57 dropping to third behind the #33 Corvette.
Despite this apparent simplicity though, the LMGTE Am results from Fuji are by far the most difficult ones to model this season. The main reason is that most teams were very close in both pace and strategy. For the first time this year there were as many as eight cars on the lead lap at the finish. Even though this was the shortest lap this season and there were no SC periods late into the race to bring the field together. As a result, our model, shown on Figure 2, fails to explain the finishing order of 4 cars by as many as 7 positions in one case.
Figure 2 shows a simple, three-parameter model which we use to explain the finishing order in the race. In the left column the cars are ordered according to their race pace measured as the mean lap time from all their racing laps (pit-in, pit-out and yellow flag laps excluded). For Hypercar and LMP2 classes we use the median as it is more stable against outliers but in LMGTE Am class there is inherent variation in performance due to different driver ratings. Changing from the median to the mean in the first column of Figure 2 has small but significant effect and brings us closer to the actual final classification.
The fastest car at Fuji was the #33 Corvette. No surprise from the world champions. The second fastest car was the #83 Ferrari 488 GTE EVO of Richar Mille AF Corse team. This was also one of the teams that spent the least amount of time in the pit- 6:43.907, only beaten by the other AF Corse Ferrari #54 by 2.1 seconds. By all accounts #83 should have finished second yet it took the checkered flag ninth, a lap behind the winning car #54. As the WRAT shows, the lap in question, was lost during their fifth stint, an hour before the end, when their bronze driver was at the wheel. Traditionally LMGTE Am teams tend to put their bronze rated drivers at the beginning of the race, allowing ample time for recovery as they could be a second or two per lap slower than gold and platinum rated drivers.
The battle for fifth and sixth positions between the Porsches #56 of Project 1-AO and #77 of Dempsey-Proton Racing with the Aston Martin #98 of Northwest AMR is another surprise that our model fails to explain. The battle unfolded at the end of the FCY period and the following 12 laps and was not covered by the TV coverage. The WEC TV also does not include on-board from any of those cars. What the WRAT shows is that #56 overtook #98 at the end of the FCY period. Several laps later #77 also passed it when all three cars had unusually slow lap.
The small margins in the closest race in this class are clearly below the accuracy of the model employed here. We will work on improving it and provide more precise explanation of the final results.
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