Posted by: drracing | November 12, 2017

WEC – Shanghai Race Analysis

Hi everybody!

Here we are again with another race analysis. This time we will deal with the penultimate round of the World Endurance Championship, that took place in Shanghai last weekend.

Before we dig into the analysis, anyway, i want to share with you a video about one of the last simulation session we run, a few days before the Chinese race and on the Shanghai circuit.
The vehicle model in use is again the 2017 WEC Spec LMP2 and the simulations we did also helped to evaluate the effects of certain setup choices on final performance.
Here a link to the video.

I think it was all around a very exciting race, with a lot of interesting topics that can be analyzed and a lot of interesting battles/dramas happening on the track, above all in LMP2.

Tyres degradation has been, as always, an extremely important point, since the teams have to always double stint their tires to respect the given allocation. In Shanghai it seems it was even more important, because of the track being particularly demanding with this respect.
Also, the race was neutralized with a FCY only once, this giving even more room for proper wheel to wheel fights and with the teams having to take care even more of their hardware.

In the LMP1 class, the race was dominated by Toyota, who seems to have found much more pace than immediately after Le Mans and that has brought some very effective Aero updates in China. It could have been an 1-2, if car n.7 didn’t have an accident with a GT car nearly at the end of the race.

LMP2 was all about Rebellion’s car n.31, who took the pole in Qualifying and, excluding the pit stops phases, never lost the lead. Senna in particular seems to be living an amazing moment, with a form and performances that no other driver on the grid seems to be able to beat currently. Behind them, anyway, a lot of interesting battles took place, with car n.38 (DC Racing – Jota Sport) who had some tense moments and left China loosing the championship lead, now in the hands of Rebellion n.31 crew.

One very interesting point during the race was how several times LMP1 cars overtook LMP2 vehicles at the beginning of the long straight before the last two corners and then LMP2 cars overtook LMP1 cars again before the braking point, because of their significantly higher top speed (LMP1 cars were coasting at the end of the same straight).

Before we start to analyze the available data in details, i have to give a word of notice about this Shanghai race analysis. For a reason I ignore (I may suppose a problem with the time detecting system), a lot of the sector times (mainly relative to sector 2 and 3) were missing in the list I found in the official website. This means, although the trends we will identify should remain trust-able and realistic, the absolute values of the averages we will look at could well be wrong.
Unfortunately this is something that goes out of my control and that seemed to hit LMP1 data more than LMP2 ones.

 

LMP1

As we mentioned, Toyota won with merit in China, their car working extremely well during the whole race both in terms of performance and tyre management. Also strategically, it looks like they did everything right.
If we take a look to the time each car spent in the pit, we see anyway that Porsche pit stops were actually slightly quicker, which give even more significance to the performance advantage shown by Toyota:

 

pit times

 

The table above actually indicates how all cars except car n.7 (who spent a long time in the garage for reparations after the accident with a Porsche GT car) did six pit stops; Porsche, anyway, spent less time in the pit, with the winning Toyota n.8 staying in the pit lane about two seconds longer than Porsche n.2 and nearly thirteen seconds more than Porsche n.1.
The advantage on pace was big enough to not only compensate these gaps but also to build a comfortable lead already short after the start.

It is no surprise to see this confirmed by the following table, listing for each car the best lap time achieved during the race, the average of the best 20 lap times, the average of the best 50 lap times, the average of the best 100 lap times and the “all clean laps average”:

 

LMP1 - Lap time average table

 

The best results for each metrics are written in red.
This table makes clear, on one side, that the two Toyota had indeed consistently more pace than the Porsche, with the gap between the two brands in each of the considered metrics staying constantly between 0.4 and 0.5 seconds, if we exclude the best laps and the “all clean laps” average.
Another interesting point is how Porsche n.2 was significantly slower than car n.1, while inside Toyota’s team, it is actually car n.7 that seemed to have the best pace, at least if we consider the best 20, 50 and 100 lap times. The gap between the two Japanese cars gets smaller and smaller as we move from the average of the best 20 laps to the “all clean” line and this is indeed what also the plots relative to the best 20, 50 and 100 lap times for each car tell us.

 

LMP1 - best 20

 

LMP1 - best 50

 

 

LMP1 - best 100

 

Some major takings, coming from these plots are:

  • car n.2 is by far the one with the worst pace throughout the race, but the question is if they really wanted to take any risk, knowing that they could bring home the championship win on race before the end of the championship
  • Porsche n.1 best lap times are indeed close to the ones of car n.8, but they get slower on the long distance
  • Car n.7 is clearly the fastest car, if we consider the best 20 and 50 laps plots
  • The two Toyota are very close to each other after the 45 mark, with car n.8 holding a small advantage
  • All cars seems to have a similar “gradient” (meaning with this how the lap times grow as we move from the best to the 100th best lap time) for their lap times curve with the exception of car n.8, with its curve staying pretty flat between the 15 and 60 mark, signalizing indeed how good Toyota’s performance was.

 

It is very interesting also to look immediately at the comparison between all cars’ lap times during the race, focusing in particular to car n.7 and car n.8:

 

LMP1 all laps - 8 vs 7

It is easy to see how actually during different phases of the races, one or the other car was quicker, with n.8 crew showing better pace during the first, third, fifth and seventh stint. Coincidentally, Toyota used a split strategy with their tyre changes, with one car changing tyres at a certain stop and the other at the following one. No surprise that each car has better performance than the other immediately after a tyre change, with car n.8 changing tyres at the second stop and then again at the forth and sixth (so before each stint where it had better pace than car n.7).

Porsche didn’t use the same approach and indeed the plot relative to the lap times throughout the race doesn’t show the “switching” feature we saw in Toyota’s one (simply car n.2 is most of the time slower than car n.1):

 

LMP1 all laps - 1 vs 2

 

Let’s now break down our analysis looking at each sector and at the speed trap data.
As often happens, the car was divided in three sectors, as shown in the following picture:

 

track map

 

The first sector includes a big part of the box straight and the first corner, which is a very tricky and long right turn where LMP cars brakes when already cornering, making it an extremely demanding and interesting point of the circuit. It is not uncommon to see different cars following completely different lines here. Beside the first corner (Turn 1 and 2 in the track map above), the first sector is composed by a second very slow left turn, followed immediately by a more open one that is seen by the drivers simply as a part of a single long bend. After a short full section section there is again an hairpin (turn 6) driven at very low speed. We can imagine, hybrid energy deployment plays here a very important role on performance.
Sector 2 is a very interesting mix of high and low speed corners: turn 7 is a very fast and long left one that lead to a slower right turn (turn 8), where the goal is to find the best line to prepare the braking for the following left one (turn 9). It leads into a relatively short straight through a second left bend (turn 10) which is run in full acceleration by LMP cars. Follows a pretty hard braking to turn 11, which is a pretty slow corner but leads into a very long right bend, where the car progressively increase their speed exiting in fourth gear and entering the longest straight of the track: this means, the exit speed of 13 is extremely important in defining final lap performance. Also in this sector, hybrid energy deployment is very important, but downforce also counts in defining how quick a car can go through turn 7 and 8.
The third and final sector is in big part composed by the longest straight of the track, where top speed and straight line acceleration play an extremely important role. The straight leads with a very hard braking into turn 14, again a very slow (right) hairpin. It is followed by a very short straight and the last corner (turn 16), a left bend which proved to be very tricky as many drivers were kept under investigation because of track limits infringements.

Let’s start with the first sector.
This is without questions Toyota’s hunting ground, with both car n.7 and car n.8 being clearly faster than both car n.1 and car n.2 and car n.7 showing a better pace than car n.8, above all if we consider the average of best 20 and 50 laps.
This is what the following table, relative to sector 1 best and average times, tells us, also underlining the small advantage of car n.7 on car n.8.

 

LMP1 - sec1 average table

 

As for the overall lap times, the gap between Toyota’s two cars reduce as we move from the best sector time to the average of the best 100 sector times and to the “all clean laps” average, with the two crews producing more or less the same results for these two metrics.
Porsche is again closer to Toyota if we consider only the best sector time, with car n.1, car n.2 and car n.8 obtaining more or less the same time, but looses ground as we move to the average of the best 20, 50, 100 and “all clean laps” sector times.
The situation appears even clearer if we look at the plots relative to the best 20, 50 and 100 sector 1 times:

 

LMP1 - sec1 - best 20

 

LMP1 - sec1 - best 50

 

LMP1 - sec1 - best 100

As we said, similarly to what we have seen analyzing the overall lap times, Toyota n.7 is faster than car n.8 if we look at the left portion of our plots, up to the 35 mark. On the right side of this point, car n.7 and car n.8 are indeed extremely close to each other.
It is also clear how both Porsche were 0.2 – 0.3 seconds slower than the two Toyota, with car n.1 performing a bit better than car n.2. Interestingly, anyway, the gap between the two Porsche remains constantly bigger than the one between the two Toyota.

As always, it is difficult to isolate the reason why Toyota was faster than Porsche in sector 1, as LMP1 cars are so technologically complex that this could also depend on more factors (aerodynamics, hybrid energy deployment, tyre management, etc). Looking to sector 2 numbers, it seems possible that downforce also played a role but this track is also particular demanding in terms of hybrid system recuperation and deployment and it would be no surprise if also on this side Toyota had an advantage

As we mentioned, sector 2 is (even more than sector 1) a sector where downforce can make a difference, since it includes two pretty fast corners (one at the beginning and one at the end of the sector, leading into the longest straight of the track) and one medium speed one. There are anyway also two very slow corner, with one in particular (turn 9) leading into an strong acceleration zone, where also the hybrid system can contribute significantly to the final performance.
And again, as for sector 1, in sector 2 the two Toyota were clearly faster than the two Porsche.

 

LMP1 - sec2 average table

 

The above table, relative to sector 2 best time and to sector 2 best 20, 50, 100 and “all clean laps” times average, see the two Toyota again on top, with car n.7 and car n.8 sharing equally the lead in each of the four metrics we consider. This time, anyway, the difference between the two crews is constantly smaller than in sector 1, with the gap between the best Toyota and best Porsche staying always between 0.2 and 0.3 seconds.
This time, the two Porsche were slower than both Toyota also if we look to the best sector 2 times overall.

The plots help again to visualize each car’s performance relative to the others.

 

LMP1 - sec2 - best 20

 

LMP1 - sec2 - best 50

 

LMP1 - sec2 - best 100

 

What these plot tell us is:

  • Both Toyota are faster than the Porsche.
  • Car n.7 show again a very high potential, above all if we consider the laps before the 35 mark.
  • After the 35 mark, car n.8 is a bit faster than car n.8, while in sector 1 they were more or less on the same performance level.
  • Porsche n.1 was sensibly faster than Porsche n.2, although car n.2 had actually a better sector 2 best time.

 

The summary of what we have seen in this first two sectors seems to suggest that Toyota could handle the more twisty / high longitudinal accelerations part of the track much better than Porsche.
This is particularly interesting thinking about the aerodynamic updates that Toyota used in China (and what could have been if they had them already before during the season), but it looks realistic to think that also on the hybrid side Toyota had some more flexibility.

Sector 3 anyway shows a pretty different situation. Sector 3 is in big part dominated by the long straight, followed by a very hard braking and a very slow hairpin. Top speed, hybrid performance and low drag play surely an important role in defining how fast a car is in this sector, but as the sector starts in a point where the cars are already traveling at high speed (exit of turn 13) and probably have already deployed a big part of their electric power, i suspect a lower drag can bring here a greater benefit.
If we look at the following table, showing the best sector 3 time and the averages of the best 20, 50 and 100 sector 3 times, we see for the first time a Porsche on top at least in some of the metrics:

 

LMP1 - sec3 average table

 

Porsche n.1 is indeed the fastest car if we consider the average of the best 50 and 100 sector 3 times, being anyway extremely close to Toyota n.7 also in the average of the best 20 sector 3 times.
It is also interesting to notice how also the performance of Porsche n.2 are pretty close to the fastest times in this sector, with n.2 crew taking the lead in the “all clean lap” average.
Porsche being here much more competitive than in the first two sectors is confirmed by the plots relative to the best 20, 50 and 100 sector 3 times:

 

LMP1 - sec3 - best 20

 

LMP1 - sec3 - best 50

 

LMP1 - sec3 - best 100

 

The first thing catching the eye here is that car n.8 is significantly slower not only than the sister car n.7, but also of both Porsche.
Toyota n.7 signs the best sector time and its performance is comparable to that of car n.1 up about to the 30 mark, but it drops a bit and also car n.2 becomes quicker on the long run.
Indeed Porsche were much more competitive in sector 3 than in the rest of the circuit.
Why this?
A small help can come from the Speed Trap data, as the TS was located at the end of this straight. As always, we have to be careful when we analyze this data for the LMP1 class, as the coasting strategies that each team uses can mix the cards a bit. Nonetheless, i think we can still get some important hints to understand each car performance:

 

LMP1 - TS - best 20

 

LMP1 - TS - best 50

 

LMP1 - TS - best 100

 

There are two things that we can immediately take, looking at these plots:

  • both Porsche were generally faster, in terms of top speed, than the two Toyotas
  • Toyota n.7 seems to be quicker than car n.8 up to the 40 mark and then drops down a bit. This seems to match also with the general performance trends of car n.7, who showed better pace than car n.8 above all to the 35-40 mark in each plot.

Top speeds analysis seems to suggest that the Porsche had either a lower drag setup than Toyota (which could also mean lower downforce, if the efficiency of Toyota really stepped up, because of the new updates; this seems to match with sector 1 and 2 performances), or a different hybrid deployment strategy, maybe prioritizing sector 3 and sacrificing a bit sector 1 and 2. Of course, also a mix of these two factors and, maybe, even others is possible. Maybe Toyota’s recovery strategy was also based on a longer recovery / coasting phase at the end of the straight. Really difficult to say.

Closing the analysis of the LMP1 class, China showed an extremely fit Toyota, most probably well helped by the small updates they installed on their cars for this race.
The Japanese cars were sensibly quicker than the Porsche and built their advantage mainly in sector 1 and 2, the most twisty ones and where downforce and hybrid energy deployment most probably play a bigger role.

 

LMP2

The LMP2 class offered a very exciting race, with a lot of drama and wheel to wheel fights, involving also the main championship players, like DC Racing car n.38.
As all the teams use the same car (Oreca 07 – Gibson), there are less major performance differences compared to what we have seen for the LMP1 class (and in some previous LMP2 races), but we can still find some interesting points.

If we start considering the overall lap performance of the first four classified cars and of car n.28 (which came to sixth place, but was much faster than car n.25 who finished fifth), the following table immediately shows us that car n.31, who finished first, actually won on merit, not only because of a perfect strategy and because they avoided any mistake, but also because they had a very strong pace:

 

LMP2 - Lap time average table

 

Car n.31 was in each metrics in our table either the fastest car or very close to the fastest times. Beside signing the best overall lap time in the race, they are also on top if we consider the average of the best 20 laps and remain extremely close to the best performances also if we look at the average of the best 50 and 100 laps. They are again the quickest if we consider the “all clean laps” metrics.
Another interesting point, anyway, is car n.38 pace. Jota Sport’s crew was indeed extremely fast and, in terms of pure performance, could be beaten only by car n.31. Their race was anyway affected by a couple of mistakes/accidents that compromised completely their final result.
The plots relative to the best 20, 50 and 100 laps help us even more to understand how each team performed:

 

LMP2 - best 20

 

LMP2 - best 50

 

LMP2 - best 100

 

The first thing to notice, looking at the plots above, is how close all the cars we are analyzing were to each other, in terms of lap performance potential.
Car n.31 was indeed the fastest if we only look at the best 20 lap times plot. Above all their best 10 laps were sensibly faster than the ones of all the other cars.
Anyway, if we move our focus on the best 50 and 100 laps, we clearly see that the line seating below all the other was actually the one of car n.38, who clearly becomes the fastest car past the 10 mark.
It is also interesting to notice how close to each other were car n.31 and car n.36 (who finished second), in terms of performance, past the 25 mark.
Another interesting point is also that all the lines in our plot seem to show a very similar gradient from left to right (from fastest to slowest laps).

With this regard, it is very revealing to look also at how the performance of each car evolved during the race, also comparing each crew to the winning n.31.
If we first put car n.31 and car n.36 together, we see that the Rebellion crew was significantly faster than the Signatech one mainly during the second and the last stint, but also that the two cars were pretty close to each other (in terms of lap times) during the rest of the race. We could even go so far and say that car n.31 seemed to manage the tyres better, as they normally showed a slower increase of the average lap times during two stints (also in LMP2 each team had to double stint the tyres). But this could also be dependent on other factors, like traffic management.

 

LMP2 all laps - 31 vs 36

 

A comparison between car n.31 and car n.38 also offers some interesting discussion points.

 

LMP2 all laps - 31 vs 38

Car n.31 was again untouchable during the second stint, with Bruno Senna at the wheel, while Jota had his silver driver in the cockpit (Laurent), although Laurent is surely one of the biggest sensation of 2017 Season and is really fast.
Anyway, car n.38 produced in several stints a better performance than car n.31 and was sensibly slower only in the closing phases of the race.
This confirms their performance potential and that their race was actually ruined by unfortunate track action situations, but not because of bad pace.

Rebellion second car, n.13, was a step behind the sister crew in terms of performance and indeed one of the slower cars in our analysis (but we mentioned already how close these five cars were to each other in terms of performance), but still managed to close third, overtaking car n.38 in the final phases.
And indeed, if we compare the pace of car n.38 and car n.13 during the whole race, the first thing that catch our eyes is the dramatic performance drop that Jota’s crew had in the final two stints, while car n.13 was able to keep running with a much better performance.

 

LMP2 all laps - 13 vs 38

 

Let’s now try to break down each car performance by looking at the sector times.

In sector 1 car n.31 and car n.38 performance are very close, with all the other crews remaining anyway not too far, above all Signatech.

 

LMP2 - sec1 average table

 

Car n.31 and car n.38 metrics are always very similar, with the gap only slightly increasing as we consider more and more laps. Car n.36 follows very close behind.
A look at the best 20, 50 and 100 sector 1 times plots helps to get a better feeling about each team’s pace.

 

LMP2 - sec1 - best 20

 

LMP2 - sec1 - best 50

 

LMP2 - sec1 - best 100

 

Car n.31 seems indeed to have a small edge on the competition in this sector, with car n.38 being very close if we look at the 20 best sector 1 times plot, but loosing a bit of ground on the long run. Car n.13 is constantly slower than the other crews in this first part of the track.
Again, excluding maybe only car n.13, all the cars we consider are incredibly close to each other up to at least the 70 mark; this underlines not only the consequences of using the same chassis but also, most importantly, how good these teams work and how close they constantly are to the limit, after one season of development of their cars, setups and approaches.

Sector 2 offers a slightly different scenario, with car n.38 being constantly very fast and car n.31 not seating on top here, although remaining always among the fastest ones.
As we mentioned already, sector 2 is at least partially downforce dominated, but we better not jump to quick on conclusions and look first to the data of this sector and sector 3 afterward.

 

LMP2 - sec2 average table

 

The table above seems to confirm, without any doubt, that car n.38 was extremely competitive in this section of the track, although again the gaps between the cars in each metrics are extremely small.
This sector seems also to suite car n.13 pretty well, on the contrary of sector 1.
Is this also what the best 20, 50 and 100 laps plots tell us?

 

LMP2 - sec2 - best 20

 

LMP2 - sec2 - best 50

 

LMP2 - sec2 - best 100

 

Car n.38 and car n.13 look very strong, both if we look at the 20 laps plots or we concentrate on the long run.
Again, all the cars are pack extremely closed together and car n.31 is not far, although not shining as they did in sector 1 and in terms of overall performance.
Did they indeed run less downforce than car n.38?

This doesn’t seem what sector 3 data tell us.
In a sector where top speed (and hence low drag) play an important role, car n.38 and car n.31 are very close to each other in terms of performance and indeed have a slightly bigger gap to the other crews we consider, compared to what happened in sector 1 and 2.

 

LMP2 - sec3 average table

 

This is what the table relative to the best sector 3 times and to the average of the best 20, 50, 100 and “all clean laps” sector 3 times tell us.
Anyway, the plots relative to the best 20, 50 and 100 sector 3 times give in my opinion a better feeling about the performance situation in this section of the circuit.

 

LMP2 - sec3 - best 20

 

LMP2 - sec3 - best 50

 

LMP2 - sec3 - best 100

 

In all three plots it is crystal clear how car n.31 and car n.38 lines constantly lie below all the others, with car n.38 having maybe a small edge up to the 50 mark.
Car n.36, that had a very good overall pace during the whole lap, was indeed a step behind Jota’s and Rebellion’s crews in this sector, as was Rebellion second car n.13.

The top speeds data seemed to confirm that car n.31 and car n.38 were running similar drag levels:

 

LMP2 - TS - best 20

 

LMP2 - TS - best 50

 

LMP2 - TS - best 100

 

Car n.31 and car n.38 have pretty much always the best top speed and this is indeed no surprise, following the analysis of sector 3 times.
Car n.36 is, on the other hand, constantly the slowest one in terms of top speed, which seems to give a reason for their slightly slower times in sector 3 and their pretty good performances in sector 2.
All of this seems anyway to leave open the reasoning behind car n.38 being slightly faster than car n.31 in sector 2: this doesn’t seem to lie on different aerodynamic configurations.
Maybe the two teams were running different mechanical setups, which could also partially explain the differences in tyre management that we discussed before; but the reason of these differences could also simply “depends” on the driving styles of the drivers composing each crew or on the different race situations in which each team found itself during the race.
In general, car n.31 seemed to be a bit more consistent than the other crews (in particular car n.38, that was the closest in terms of performance), but they also had the (well deserved) advantage of being constantly in front, this giving a chance to manage the race instead of having to chase it, as it was the case for car n.38 during many phases; they most probably could not run in “save mode” and maybe had to stress its tyres much more (see for example the accident and relative spin that car n.38 had during the confrontation with G-Drive car, which surely didn’t do any good to the set of tyres they were using during that stint).

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