Posted by: drracing | September 24, 2017

WEC – COTA Race analysis

Hi everyone!
This post will be again an attempt at an Race analysis, as i did in my previous one. This time we will look at WEC COTA race data.
Once again, i hope i will not come to completely wrong conclusions, trying to understand the how and why of this race (in terms of performance) by just looking at the numbers openly available online

Let’s start by saying, it was a very interesting race, with a pretty close battle (at least up to a point) in LMP1 and with very nice discussion points in LMP2 too (although having in the WEC only one chassis maker, there is some less variety, also in terms of performance, compared to the ELMS).
The race had only one safety car neutralization, with this being made not with a full course yellow, but letting the safety car into the track, practically deleting any existing gap for many of the track battles that were taking place.

Temperatures were very high and this has surely been an important element, also in terms of tyre degradation.
LMP1 teams also always had to double stint their tyres (i am not sure if LMP2 teams also did it, unfortunately i could not take note of every pit stop) and Toyota and Porsche did that in different moments during the race (Toyota double stinted its first set of tires, while Porsche did change the tyres at the second stop, following always alternating one stop with full service and one only with fuel and driver change only). That lead to interesting situations on track too, since the two marques often had a different tyre status in a certain phase of the race.

We will look at LMP1 first and then move to LMP2.

LMP1

The race has been won by Porsche, who also put in place team orders to favor their championship leading car (Car n.2), despite being car n.1 most of the race slightly quicker.
The good surprise was that Toyota, after having shown no promising pace in qualifying, was pretty much close to Porsche during the race, with very exciting attrition taking place on track between car n.1 and car n.7 in a fight for second place.
During the race, car n.8 also suffered a small issue with the hybrid system, apparently becoming unable to play with the boost “freely” when needed (for example for an overtake maneuver) but still managed to end up in front of the sister car.

Looking at the fastest laps first, Porsche was slightly ahead, but with a much smaller gap than what we saw in qualyfing:

Porsche #1:      1’47.149
Porsche #2:      1’47.302
Toyota #7:        1’47.391
Toyota #8:        1’47.556

The gap between the two big teams stays more or less the same also if we look at the average of the best 20 laps:

Porsche #1:      1’47.768
Porsche #2:      1’47.908
Toyota #7:        1’48.022
Toyota #8:        1’48.011

Car n.1 is still the quickest and this was a topic of discussion during the race, since its performance was clearly sacrificed to favor car n.2, currently leading the world championship. The two Toyotas are extremely close together, but the situation changes already a bit if we look at the average of the best 50 laps:

Porsche #1:      1’48.135
Porsche #2:      1’48.279
Toyota #7:        1’48.353
Toyota #8:        1’48.470

As we can see, the gap between Toyota and Porsche becomes slightly smaller and the Toyota n.7 seems to now show more pace than the sister car. It is still amazing to see how close each car is to the others, to underline (if necessary) how good the drivers are and how intense is the competition.
If we consider now the average of the best 100 laps, we start to see the effects of team orders inside Porsche, with car n.1 and car n.2 being extremely close.
As a consequence, the gap between Porsche and Toyota becomes even smaller than before:

Porsche #1:      1’48.630
Porsche #2:      1’48.681
Toyota #7:        1’48.763
Toyota #8:        1’48.875

Interestingly, Toyota n.7 car is still faster than car n.8.
If we finally look at the “all clean laps” average, we still see a similar situation but with the gap between Toyota and Porsche now stretching again a tiny bit:

Porsche #1:      1’49.416
Porsche #2:      1’48.485
Toyota #7:        1’49.568
Toyota #8:        1’49.514

Car n.1 is still the fastest, while car n.8 becomes faster than car n.7.

Just looking at the numbers, we can identify how, on one side, Porsche had a small advantage on Toyota (above all considering car n.1) in terms of pace and how car n.1 was clearly the quickest.
This seems to be confirmed also by the plots looking at the best 20, 50 and 100 laps.

 

LMP1 best 20 laps

 

LMP1 best 50 laps

 

LMP1 best 100 laps

 

We immediately see, once again, how car n.1 has the best pace, with the only exception being in the window after the 65th best lap, where it becomes slightly slower than car n.2.
if we look at the best 20 laps plot only, the two Toyota seem to be very close to each other; but pretty big gap between the two emerges after the 22nd best lap mark, with car n.8 becoming sensibly slower than car n.7, at least up to the 90th best lap mark.

Clearly, in this second phase of the season Porsche has an advantage on Toyota. It can be anyway interesting to try to understand if there are some track sections where the gap is bigger and we will try to do this by looking to sector times.
The track was divided in three sectors, as shown in the following image:

 

track map

 

A first relatively short first sector is followed by two longer ones. Last sector is a pretty twisty one, with several slow corners and a very long right double bend (turn 16, 17 and 18) where both tyres and aerodynamics are very important, followed by a medium speed left corner (turn 19).

Analyzing the first sector, if we would just look at the best times of each car, we could come to partially wrong conclusions. The two Porsche are clearly in front, but the situation changes slightly when looking at the average of the best 20, 50 and 100 laps.

First Sector best times:

Porsche #1:      22.567
Porsche #2:      22.737
Toyota #7:        22.891
Toyota #8:        22.936

First sector best 20 times average:

Porsche #1:      22.962
Porsche #2:      22.968
Toyota #7:        22.960
Toyota #8:        23.007

First sector best 50 times average:

Porsche #1:      23.046
Porsche #2:      23.05
Toyota #7:        23.004
Toyota #8:        23.047

First sector best 100 times average:

Porsche #1:      23.121
Porsche #2:      23.133
Toyota #7:        23.061
Toyota #8:        23.099

 

We immediately see how, actually, all the car have pretty similar performances, also because we are dealing with a very short sector. We also notice how the Toyotas stay more constant, compared to the Porsches and become slightly quicker than the competitors already in the best 20 laps average (car n.7).
Since the first sector is mainly composed by the box straight and the first corner, could it maybe lie in the hybrid boost strategy/flexibility? We are of course just speculating, the cars could also have different aerodynamic properties, or different traction in corner exit, just to name a few possible reasons.

Interestingly enough, if we look at the “all clean laps” average, the situation bends even more in favor of Toyota:

Porsche #1:      23.292
Porsche #2:      23.304
Toyota #7:        23.2
Toyota #8:        23.243

If we look at the plots relative to the best 20, 50 and 100 first sector times, we can pretty much confirm what the average times told us. On the single quick lap, Porsche seems to have an advantage, but on the all race pace, Toyota is slightly quicker.

 

LMP1 best 20 sec1

 

LMP1 best 50 sec1

 

LMP1 best 100 sec1

Each of the three plots above shows how car n.7 is constantly the quickest in the first sector, excluding the very left portion of the window. Car n.8 is a bit slower and lies below Porsche’s pace for at least the best 5-6 laps, but after the 20-mark becomes clearly the second quickest car.

What about sector 2? The situation looks exactly the opposite as in sector 1, with Porsche cars being clearly and constantly quicker than the two Toyota; no matter if we look at the best time overall, the average of the best 20, 50, 100 or “all clean laps”, Porsche seems to retain a pretty sensible advantage, with car n.1 looking again stronger than car n.2, while the two Toyota are closer to each other.

Second Sector best times:

Porsche #1:      40.476
Porsche #2:      40.786
Toyota #7:        40.815
Toyota #8:        41.122

Second Sector best 20 times average:

Porsche #1:      40.793
Porsche #2:      40.952
Toyota #7:        41.238
Toyota #8:        41.287

Second Sector best 50 times average:

Porsche #1:      40.955
Porsche #2:      41.062
Toyota #7:        41.385
Toyota #8:        41.403

Second Sector best 100 times average:

Porsche #1:      41.161
Porsche #2:      41.210
Toyota #7:        41.576
Toyota #8:        41.571

Second Sector all clean laps average:

Porsche #1:      41.573
Porsche #2:      41.687
Toyota #7:        42.031
Toyota #8:        41.935

The plots of the best 20, 50 and 100 sector times tells more or less the same story. Toyota’s lines are always and sensibly above Porsche’s ones.

 

LMP1 best 20 sec2

 

LMP1 best 50 sec2

 

LMP1 best 100 sec2

 

Again, we could speculate trying to understand why Toyota is slower than Porsche in this sector. Personally, it is for me not straightforward to come to a conclusion, because sector 2 is actually a combination of a very demanding sequence of corners where both Aerodynamics and mechanical grip play an important role, then followed by two segments where top speed, hybrid boost and corner exit traction are surely very important.
Analyzing top speeds, we can try to get a better insight about the main performance differences between the two manufacturers, assuming both cars has a similar overall engine power and similar boost effects on terminal speed (which is unfortunately not necessary the case, but we don’t have any better data than this to try to understand where the differences are).
It is not hard to notice how, since the introduction of their high downforce kit in Nürburgring, Porsche seems to have gained a good advantage on Toyota, in terms of pure performance. The 919 has most probably more downforce than the TS050, maybe even with a small edge in term of aerodynamic efficiency, but here we are already speculating. What we could see analyzing both marques top speeds is that the Porsche (above all car n.1) seems to be a bit slower than the Toyotas, while car n.2 has more similar performances.
If we look to the plots relative to the best 20, 50 and 100 top speeds achieved during the race, we can identify a pretty clear trend.

 

LMP1 best 20 TS

 

LMP1 best 50 TS

 

LMP1 best 100 TS

 

The first thing we can clearly see is that Porsche n.1 has constantly the lowest top speed, if we exclude the best top speed overall. This could mean, assuming the coasting strategy were not too different than the one of Porsche n.2,  that car n.1 maybe had an higher downforce set up and, even if paying this in terms of drag, this choice seems to have paid in terms of performance.
The second thing is that Porsche n.2 and Toyota have similar top speeds, but Porsche n.2 is still quicker than both Toyota cars in the second sector. This seems to suggest that the 919 has effectively a similar drag compared to the TS050, but a higher downforce and hence a better efficiency.
We could get some more data to evaluate this point also by looking at the third sector times. Last sector’s performance is also very much handling-driven, since the combination of slow and fast corners surely requires a very good combination of low speed (mechanical) grip, downforce and traction.

Let’s start looking to the best sector time overall and best average sector times first.
The situation is pretty well balanced, with Toyota having a small advantage on Porsche:

Third Sector best times:

Porsche #1:      43.103
Porsche #2:      43.266
Toyota #7:        43.073
Toyota #8:        43.079

The two Toyota are amazingly close to each other and a bit quicker than the two Porsche, with car n.1 following very close and car n.2 being about 0.2 seconds slower.
The situation remains extremely close even when looking to the best 20, 50, 100 and “all clean laps” averages:

Third Sector best 20 times average:

Porsche #1:      43.579
Porsche #2:      43.603
Toyota #7:        43.584
Toyota #8:        43.461

Third Sector best 50 times average:

Porsche #1:      43.841
Porsche #2:      43.795
Toyota #7:        43.727
Toyota #8:        43.726

Third Sector best 100 times average:

Porsche #1:      44.078
Porsche #2:      44.016
Toyota #7:        43.899
Toyota #8:        43.940

Third Sector “all clean laps” times average:

Porsche #1:      44.453
Porsche #2:      44.462
Toyota #7:        44.360
Toyota #8:        44.361

As we said, there is in general a pretty well balanced situation, with one car gaining or loosing its ranking position depending on the average we consider, but with differences to its mate car and to the other brand that stay more or less always pretty constant.
Toyota is slightly quicker in this segment, but the gap between the two brands is really small.
This is confirmed also by the plots relative to the best 20, 50 and 100 sector 3 times.

 

LMP1 best 20 sec3

 

LMP1 best 50 sec3

 

LMP1 best 100 sec3

 

We can see the Toyotas are constantly slightly quicker than the two Porsches, with car n.8 signing the best 20 laps, but falling a bit behind car 7 after the 25th best lap mark.

A final note about the pit stops each team did. The strategies proposed by Toyota and Porsche were pretty much aligned, with both teams double stinting their tyres. The main difference was that Porsche changed the tyres in the first pit stop and double stinted the second set, while Toyota went for double stinting the first set and did a first shorter pit stop.
Anyway, if we look at the overall time spent in the pit the two teams were pretty much aligned, with Toyota overall pit time being only slightly higher.

Porsche #1:      396.473
Porsche #2:      396.361
Toyota #7:        397.762
Toyota #8:        398.31

Also, all pit stops happened very close to each other.

 

LMP2

The LMP2 class has also produced a very interesting race, with exciting track action. Even if the WEC misses the technical variety of the ELMS series in terms of chassis manufacturers, the extremely high quality of teams and drivers ensure always a top level show.

COTA races was dominated by Signatech Alpine, that was able to succeed with a comfortable gap on the second classified car (Rebellion car n.13) even with one more pit stop of about 46 seconds, required to repair a a rear light and even if they had to double stint the tires with Menezes (who felt several positions during that stint), because they used two sets during the qualifying. Also, the safety car that was sent on the track during the race surely didn’t help them, but they really have been stronger of any odd in Texas.

We will look at the first five classified cars, run respectively by Alpine, Rebellion and DC Racing / Jota.

All of them did 7 pit stops during the race, with the exception of the winner crew (already mentioned) and DC Racing Car n.37, that pitted 8 times.
The overall pit stop times are shown here:

Signatech – Alpine #36:       546.293
Valiante – Rebellion #13:    506.293
Valiante – Rebellion #31:    536.899
DC Racing #38:                     482.938
DC Racing #37:                     546.526

In terms of performance, car n.36 has always been among the quickest cars on the track, also running the fastest lap during the race and being clearly the fastest if we look at the 100 best laps and “all clean laps” average:

Best Lap times:

Signatech – Alpine #36:             115.427
Valiante – Rebellion #13:          115.616
Valiante – Rebellion #31:          115.695
DC Racing #38:                           116.094
DC Racing #37:                           115.434

Best 20 lap times average:

Signatech – Alpine #36:            116.578
Valiante – Rebellion #13:         116.532
Valiante – Rebellion #31:         116.925
DC Racing #38:                          116.781
DC Racing #37:                          116.302

Best 50 lap times average:

Signatech – Alpine #36:            117.190
Valiante – Rebellion #13:         117.174
Valiante – Rebellion #31:         117.620
DC Racing #38:                          117.542
DC Racing #37:                          117.246

Best 100 lap times average:

Signatech – Alpine #36:            117.728
Valiante – Rebellion #13:         117.870
Valiante – Rebellion #31:         118.099
DC Racing #38:                          118.284
DC Racing #37:                          118.351

“All clean laps” lap times average:

Signatech – Alpine #36:            118.569
Valiante – Rebellion #13:         118.997
Valiante – Rebellion #31:         118.982
DC Racing #38:                          119.564
DC Racing #37:                          119.698

The first thing to notice is that car n.36 looses the “lead” in the above lap times averages only in the best 20 and 50 lap times average (still being anyway always very close to the fastest car), but is clearly in front of all the others again in the best 100 lap times average.
It is also interesting to notice how car n.37 has indeed a very competitive pace if we look at the best lap times, best 20 and 50 lap times average, being either the fastest or very close to the fastest car in each of these classifications. Anyway, its performance falls down if we look at the best 100 and “all clean laps” lap times average, with a pretty big gap to car n.36.
It is not a case that, during the first half of the race, car n.37, with Brundle at the wheel, was able to climb the ladder up to P1, with a lot of very exciting overtakings. If we look to the best 20 laps plot, Car 37 is extremely competitive.

LMP2 best 20 laps

 

Anyway, already looking at the best 50 laps plot, the situation changes completely and car n.37 shows a very strong fall off after the 25th mark

 

LMP2 best 50 laps

 

Looking at the best 100 laps, finally, we see as car 37 performance drops really dramatically with the crew becoming the slowest of the first 5 classified cars after the .. mark:

 

LMP2 best 100 laps

 

On the other side, looking at the best 50 and 100 laps plots, we can see how car 36 is the one staying more constant in terms of performance, not producing the best lap times up to the 10-15 mark, but clearly becoming the quickest after the 35 mark, showing the smallest performance degradation.

It would be interesting to try to understand what exactly lead to car n.37 being so fast in certain phases and much slower in other moments of the race. As we have seen also analyzing ELMS Paul Ricard race, the pace of the non-professional driver seating in the car can really define the race, but was it really a problem with the slower driver here?
If we look at following plot, showing the lap times every car did at every lap, we can see once again, on one side, how constant car n.36 was, but also how other car was affected by both different drivers performance or by performance degradation:

 

LMP2 stints analysis

 

Although the plot seems simply messy, we can identify a few interesting points:

  • car n.36 line is the one staying averagely more horizontal
  • same cars had apparently very slow stints, like car n.38 in its second and car n.13 in its third
  • some cars show more performance degradation during a single stint, like car n.37 in the last stint and car n.38 in the third one.
  • car n.37 was the quickest on track during the second stint

 

If we compare each car to car n.36, it is a bit easier to identify what happens during each stint:

LMP2 stints analysis 36-13.JPG

 

This first plot shows car n.13, compared to car n.36. We can see how car 13 was particularly slow in its third stint (the non professional driver was in the car), but slightly quicker in stint n.2. Also, both cars seems to show a pretty constant performance in each stint, with the lap times line not going up too aggressively (which means no extreme pace degradation), if we exclude stint 3 for car n.13.

The following plot is a comparison between car n.31 and car n.36:

 

LMP2 stints analysis 36-31

 

Both cars seem pretty constant, but car n.31 is slightly slower during pretty much the whole race (excluding maybe the fourth stint), as confirmed also by the best laps plots.

 

LMP2 stints analysis 36-38

 

If we look at the previous plot, showing a comparison between car n.36 and car n.38, things get more interesting. Car n.38, even if showing sometimes comparable pace to car 36, seems to suffer of a much stronger performance degradation during a single stint, as we can see looking to the second, fourth , sixth and last stint (lap times lines goes up). We could suspect this happens mainly during the second stint done with a certain set of tyres, but i am honestly not sure this is really the case, since i could not follow when they exactly did their tyre changes.
The same tendency is even more evident if we look at the comparison between car n.37 and car n.36:

 

LMP2 stints analysis 36-37

 

Car n.37 has a tremendous pace during its second stint (ad this is well confirmed by the 20 best laps plot, where car n.37 is clearly the fastest), but is slower in pretty much all the other stints and shows also a much more pronounced performance degradation in every second stint, as the sister car n.38.

I will not go through the track sectors analysis for the LMP2 class, since, because of the absence of chassis variety in the WEC, we would simply confirm the same tendencies we saw analyzing the overall lap performance.

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