Due to the thin air, the drag of a Formula One car in Mexico City is much lower. There are fewer air particles for the car to move out of the way, which means that a Formula 1 car is able to cut through the air quicker and with less disruption. As a result, the cars are very fast on the straights in Mexico, with a maximum speed higher than Monza (350 km/h) while at the same time running wings as big as the ones we use in Monaco.
However, fewer air particles also have the impact of less downforce being generated, as there is less air pushing the car into the ground. In fact, the downforce loss is around 25% in Mexico due to the altitude. As a result, the highest downforce specification – Monaco level of wing – is used at Autodromo Hermanos Rodriguez but this is generating the same level of downforce (or even slightly less) as the Monza wing because of the lack of air density.
Aero grip is therefore pretty low in Mexico, but you can run a big wing without the penalty of drag, so top speeds are very high.
If we would be evaluating naturally aspirated engines, the performance difference at a high-altitude track would be much higher, taking into consideration the fact that it relies on oxygen being drawn into the engine in order to complete the combustion process. This would produce a 25% performance loss, but on the modern-day Formula 1 Power Units this is avoided thanks to the Turbocharger.
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This is because the Turbo spins at an incredibly high speed to pump more air into the engine – around three times more air, in normal altitude conditions. More air means you can pump in more fuel and therefore generate more power. In Mexico, the Turbo has to work harder to compensate for the lower air density and it does this by spinning at a higher speed, in its attempt to make up some of the performance loss.
Yet it can’t make all of the performance difference up. Working the Turbo 20% harder just isn’t possible – there isn’t the margin left, because they are designed and built for normal race conditions, not the unique ambient pressure of the Autódromo Hermanos Rodríguez. So, there is still a sizeable reduction in Power Unit output, but the lower drag helps make up for that and propel the cars to these incredible maximum speeds on the Mexico City track’s long main straight.
There is also less harvesting from the MGU-H in Mexico because less air into the engine means less power and less exhaust gasses for the MGU-H to recover and turn into useful energy. Some manufacturers will fare better than others depending on the size of their Turbo and the layout of their Power Unit system.
This means that team such as Red Bull, Scuderia Ferrari, Alpine and Williams will be able to make good use of their draggier chassis; on the contrary, the aerodynamic efficiency – a real boost on those lower-altitude straights – of the McLaren, Mercedes and AlphaTauri packages could turn into a deficit on this circuit, giving high hopes for the Maranello team in its fight with McLaren. On the other hand, the advantage which Mercedes and Red Bull have over Ferrari will definitely not just go away at high altitude; however, the gap between them could be as narrow as it was in Monaco – with Mercedes in the role of the underdog and McLaren behind in the direct comparison – and between Verstappen and Pérez there could be more than one opening for the two drivers of the Maranello team.
The Ferrari SF21 showed it can be strong on high-downforce tracks, and it has been even more convincing since the ERS upgrade. Charles Leclerc has taken two pole positions this season (Monaco – the best chance, which unfortunately ended with a DNS – and Baku), and he should not be underestimated this Saturday in Qualifying, as well as on Sunday in the race. Not to be discounted either, Carlos Sainz achieved his best qualifying result (P2) in Sochi in the wet, and has been on the podium three times since he started wearing red.
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