Mark Hughes: The data that debunks wild Piastri conspiracy theories

After two consecutive off-the-pace races have lost Oscar Piastri his championship lead to team-mate Lando Norris, there are predictably wild sabotage accusations from the vocal part of F1’s fan base. Why is a driver who has been at least as quick as Norris in the season up to Austin, they ask, suddenly half-a-second or more off his pace in two consecutive races?

It’s actually relatively easy to explain when you have the data in front of you and the knowledge of how the tyres interact with the track surface and what effect that has on how the car behaves and how in turn that impacts upon the different way each driver feels the car.

We have the privilege in the current F1 to have a lot more data available than in previous years. In fact, way more than the teams themselves would have had back in, say, the 1980s, before telemetry had become so sophisticated and prior to the advent of GPS.

Had we had such data available in 1989, as McLaren team-mates Alain Prost and Ayrton Senna were fighting over the destiny of the world championship, much as McLaren’s current drivers are, we would likely have found something far more indicative of a blatant favouring of one driver (Senna) over the other. Probably at the hands of Honda.

As the championship entered its late stages, Prost had a significant championship lead. There was no question that Senna was a quicker driver, especially in qualifying, but Prost’s better finishing record had him 20 points ahead with four races to go. But Prost announced in the week before the Italian Grand Prix that he was leaving McLaren at the end of the year to join Ferrari in 1990. It would be understandable that the team – including the engine partner Honda – would prefer the driver who was staying to win the championship. But there was a big points deficit to make up for that to happen.

Suddenly, Senna’s speed advantage became ludicrous. Around Monza, a circuit with seven corners, Senna qualified 1.7sec (yes, one-point-seven) faster than his team-mate. A gap big enough for the two Ferraris to insert themselves into. It wasn’t one of those situations where Prost had suffered a problem and didn’t get the lap in; no, they each had their normal run through the sessions and Senna’s qualifying lap was 1.7sec faster in a supposedly identical car against one of the sport’s greatest drivers. It was a blatant and obvious horsepower advantage. Prost had earlier wondered why Senna had the attention of around 20 Honda engineers while he had four. Now he was understanding why.

But whatever especially potent engine spec Honda had devised for Senna, it didn’t last in the race, blowing up spectacularly on lap 44, dumping oil onto the rear tyres as he approached Parabolica and spinning from a comfortable lead into retirement. Prost won the race – and deeply upset McLaren boss Ron Dennis by dropping the winning trophy from the podium down to the Ferrari fans below.

Around the less power-sensitive Jerez for the Spanish Grand Prix, Prost was ‘only’ 1.1sec off and still he felt he wasn’t getting equal equipment. Senna won the race, Prost was a distant third. From there, they went to the Honda-owned Suzuka, where Senna’s ridiculous 1.7s qualifying gap reappeared. Thus, the scene was set for Prost to seal the title as the pair collided in the race, Prost blatantly turning in on Senna into the chicane. It was untypical of Prost, but he probably saw it as his way of fighting back against what he saw as an injustice in the only way that was left open to him.

Back then it was pretty clear what the situation was and why – and had we had access to the level of data we have today it would doubtless have been very easy to provide the supporting evidence. Today, the situation is totally different. No one is about to leave the team and McLaren has zero to gain in providing one driver with an advantage over the other. Furthermore, we can look at the GPS data, talk to the tyre engineers and even go onboard for the lap to see where the differences are.

As McLaren team principal Andrea Stella has pointed out, both Austin and Mexico City featured very low-grip surfaces and Piastri simply didn’t adapt his driving to that as well as Norris. They have quite different techniques. They load the car up on corner entry in a very different way almost everywhere. But around these two tracks on these days, it left Piastri trailing by around 0.5sec.

Looking in detail at Mexico, the particular challenge around the high-altitude, smooth surface here is to have the fronts up to temperature by Turn 1 but not have the rears overheating by the final section. That’s much more difficult to do than at other tracks where a similar trade-off is required (Barcelona, Hungary, Abu Dhabi) because the super-smooth circuit does not give the tyre much to grab hold of, meaning the mechanical grip mechanism of the tyre’s hysteresis (how its structure bends to oppose the forces) is not very powerful.

This puts extra load into the tread surface of the tyre which tends to overheat. As it overheats, so it is feeding fewer loads into the carcass, which remains under-temperature and inflexible. It’s much more difficult here to get the whole process going of feeding enough loads into the carcass to get it working before the tread has become too hot.

Norris’ pole lap was 0.588sec faster than Piastri’s eighth-place lap. All of that – plus a little more – is accounted for by Piastri losing 0.25sec into Turn 1 (fronts not up to temperature) and 0.343sec in the long, slow final corner (rears too hot). A total of 0.593sec in those two corners. Through the rest of the lap they are nip-and-tuck as their different driving styles play out much as they usually do. Yes, Piastri loses time in the fast Turn 9, which is not typical, but he’s generally quicker through the slower Turn 4-5-6 sequence.

Piastri’s 0.343sec loss in Turn 16-17 comes as he has more understeer upon entry, more lock applied as the power comes in and therefore more oversteer on the exit, overheating the rear surface even more. He is not getting the car rotated as well, simply because of the different way his driving style is working the front tyres. We see it also on the time loss in Turn 1. As they approach that turn, Norris eases partly off the throttle and overlaps that phase with the beginning of his braking whereas Piastri, braking later and going straight from full throttle to none, does not overlap throttle and brake.