Wednesday, 9 September 2015

Porsche - dominating the WEC?

Porsche’s win at Le Mans in June may have come as a surprise, but their win at the Nürburgring ten days ago was predictable from the moment that Hans-Joachim Stuck waved the flag to start the race. Audi Sport Team Joest may have threatened occasionally through practice, but once the race started, it was clear that only mechanical frailty was going to stop the Porsche steamroller.

Porsche’s test programme has taken them through the various weaknesses of the 919 Hybrid, and one by one, these have been addressed – to the point where the Weissach cars put their rivals from Ingolstadt well and truly in the shade in the sunshine and soaring temperatures in Germany.

Take a look at the average lap times from the best 20% of green laps completed:
Lap Times
No. Car Drivers Best Lap Average of best 20%
1 Toyota Davidson/Buemi/Nakajima 1m 40.207s 1m 40.940s
2 Toyota Wurz/Sarrazin/Conway 1m 40.738s 1m 41.374s
7 Audi Fässler/Tréluyer/Lotterer 1m 38.611s 1m 39.768s
8 Audi Di Grassi/Duval/Jarvis 1m 38.608s 1m 39.581s
17 Porsche Bernhard/Webber/Hartley 1m 38.307s 1m 38.904s
18 Porsche Dumas/Jani/Lieb 1m 37.955s 1m 39.129s

Notice how the average lap time of the no. 17 Porsche is much closer to its best than any of the other cars. There is no doubt that the Porsches were quicker, this time.

Remember, at Le Mans there was nothing to choose between the average times of Audi and those of Porsche, and in addition, there has been a change to the Equivalence of Technology since Le Mans, which has handed Audi an additional 0.5kg/h of fuel (up from 79.0kg/h to 79.5kg/h) and reduced Porsche’s from 88.5kg/h to 87.0kg/h. Both teams also had a reduction in fuel capacity, but this would not have affected the raw pace of either car.

So, in theory at least, the casual observer might have expected the Audi to have been quicker – certainly not 0.5% slower. Except that Porsche brought what were effectively two new cars to the Nürburgring. In particular, the new cars featured a new, high-downforce aero kit, which had not been previously raced during the season.

At Silverstone – in conditions that were very different from those at the ’Ring – Audi used a high-downforce configuration, whereas Porsche was focussing its preparation on Le Mans, and had its cars very much closer, aerodynamically, to the configuration that it was to run at Le Mans. As a result, the average lap times of the Audis were a degree quicker than the Porsches.

Spa saw the debut of the Le Mans-aero Audis, and in terms of raw pace, this was the first time that Porsche’s race pace was quicker than Audi’s – to the tune of around 0.4%. Despite its pace, in the race, the Porsche used up its allocation of 24 tyres, and ended up with dramatically slower lap times as the tyres went into their second stint. The Audis, on the other hand, seemed to float above the tarmac: Benoît Tréluyer actually triple-stinting his Michelins in his final shift behind the wheel.

At neither Le Mans nor Nürburgring were tyres an issue – the regulations allowing teams to use eight sets of tyres in what was scheduled to be a seven-stint race in Germany – and Porsche’s dominance allowed them to overcome problems for both their cars.

In the early stages of the race, it seemed that either Timo Bernhard was deliberately holding up the Audis to allow Neel Jani to establish a lead, or that he had a problem of some sort on the car. Consider this:

Before/After FCY Comparison
No. Driver Average of laps 2-9 Average of laps 13-23
17 Timo Bernhard 1m 39.504s 1m 42.404s
18 Neel Jani 1m 39.128s 1m 40.379s

(In case you have forgotten, the FCY came between laps 10 and 12.)

In fact the explanation was that a dive plane had failed on the Porsche, ruining the balance of the car. Coincidentally, Marcel Fässler suffered a puncture on the Audi and headed for the pits, just as Bernhard gave up the struggle and brought the Porsche in for a new nose section.

From here on in, the no. 17 Porsche had it all its own way, continuing to lap quicker than anyone else. However, in addition to looking at lap times, it is also worth looking at top speed: a sure indication of how teams were playing the drag/downforce balancing act.

Top Speeds
No. Car Drivers Top Speed (km/h)
1 Toyota Davidson/Buemi/Nakajima 303.9
2 Toyota Wurz/Sarrazin/Conway 311.2
7 Audi Fässler/Tréluyer/Lotterer 316.2
8 Audi Di Grassi/Duval/Jarvis 317.1
17 Porsche Bernhard/Webber/Hartley 311.2
18 Porsche Dumas/Jani/Lieb 312.0

From this, there doesn’t seem to be much doubt that the Audi was not running much downforce – surely, with the benefit of hindsight, a mistake given the disparity in lap times?

The penalties that affected the no. 18 Porsche came as a surprise. To be clear, the penalties were for exceeding the so-called ‘instantaneous limit’, which relates to the maximum permitted fuel flow measured in kg/h. This should not be confused with the ‘energy limit’, which limits the amount of energy (in MJ) used per lap. It is far less likely that the latter will be exceeded, since it can be averaged over three consecutive laps.

As I have already said, the limit for Porsche had been reduced for the Nürburgring race, from 88.5kg/h to 87.0kg/h. Interestingly, the offending laps, according to the official bulletins, were not even that fast. Compare these with the average of the best 20% lap time for the Porsche of 1m 39.129s.

Fuel Limit Offence - Porsche
No. Driver Lap No. Lap Time
18 Neel Jani 27 1m 40.309s
18 Neel Jani 28 1m 40.547s
18 Marc Lieb 46 1m 39.482s
18 Marc Lieb 47 1m 41.205s

According to Porsche, a sensor on the engine malfunctioned, resulting in too much fuel being pumped through to the engine. Once this had been identified, it was switched off, as apparently (how very Porsche), it had a redundancy. Not before three stop/go penalties had been applied though, of five, thirty and sixty seconds. The total delay for the Porsche – accounting for the time lost driving through the pit lane as well – was around 2m 30s, which is roughly what the gap was between the two 919s at the end of the race (bearing in mind that they were separated by a lap). So it is fair to say that there was no real difference over the course of six hours, between the two cars.

There were suggestions (borne out by the difference between the best and average lap times) that Audi was not as consistent as Porsche’s. My preferred method for measuring consistency is to look at the standard deviation (a statistical term for measuring the spread of values around their mean) of the lap times – and this suggests that, if anything, the standard deviation of Audi’s lap times was actually less than that of Porsche. (Clearly, for this purpose one has to exclude pit stops, yellow periods, etc.) But certainly the consistency of the no. 17 car was better than the others.

Finally, a quick look at the performances of the individual Porsche drivers.

Porsche Driver Comparison
No. Driver Laps Best Lap Time Average Lap Time
17 Timo Bernhard 58 1m 38.422s 1m 38.758s
17 Mark Webber 81 1m 38.307s 1m 38.912s
17 Brendon Hartley 64 1m 38.428s 1m 39.020s
18 Romain Dumas 33 1m 38.822s 1m 39.420s
18 Neel Jani 107 1m 37.955s 1m 38.846s
18 Marc Lieb 62 1m 39.188s 1m 39.577s

The World Endurance Championship reconvenes at the Circuit of the Americas in Texas next week, and the LMP1 cars are going to be limited to six sets of (slick) tyres for qualifying and the race. Porsche will no doubt be hoping that their high-downforce configuration will preserve the tyres, since they will have to double-stint them at least once. And surely Audi will revert to a Silverstone-style high-downforce configuration for their two R18 e-tron quattros?

It will be dark for more than half of the race, which should see temperatures coming down from their seasonal high of the low thirties (Celsius), to more manageable levels, but if Audi doesn’t find some pace from somewhere, then Porsche is going to make the remainder of the season look very straightforward.

1 comment:

  1. Another great article! Thanks!
    Porsche seems to be doing "the perfect job" at WEC. Toyota almost did it in 2014.
    A key factor was the option of preparing the Le Mans version first. Toyota and Audi were preparing first the high down force version, wasting precious time.
    Audi Le Mans version is even better that the high down force version at regular tracks.
    Le Mans is special and unique. After Le Mans is almost a regular championship with regular tracks layouts.
    Once Le Mans work is done, Porsche created an almost new chassis/bodywork full dedicated for the regular tracks for the remaining season.
    At this point, the others just don't have time to catch Porsche, even if they know how to do it.
    Toyota already forgot the 2015 season. The incredible bad judgement, simply to saving money (Toyota is the biggest but also the most profitable world car maker) was almost amateur.
    Audi is still in the hunt for the 2015 title, anyway. But they have to wait for mistakes of Porsche and be perfect on their own.
    But Porsche made great progress not also in speed, but in everything else. Porsche are know the quickest team at the pit stops (about of 5 second each), dealing with strategy as good as the Joest Team and with a full reliable car.
    In conclusion, we are in the presence of the Book of Endurance, written by Porsche. This is is the way to do it.
    New standards were created in 2015.