The Autodromo Hermanos Rodriguez track of Mexico means a big challenge for engineers and drivers because of its high altitude. Engineers have to calibrate the whole car, especially its cooling systems for the “thinner” air.
Previously the Interlagos track in Brazil was the highest track on the F1 calendar with its altitude of 800m. Its place was taken over by the Autodromo Hermanos Rodriguez race track as the Mexican circuit sits at 2,2km above sea level.
As people can feel the difference in air density while climbing a mountain, race cars suffer in a similar way from the thinner air. Not only the internal combustion engine and cooling are affected by it, but it also has an effect on the downforce.
Turbocharger with key role
Internal combustion engines rely on the air because of their working principle. As oxygen plays a key role in the burning process, its amount in the air is very important. The higher a place sits above the sea level, the thinner the air gets, so the less oxygen it contains.
F1 engines are so sensitive that they can feel even the change of oxygen amount due to temperature changes. It has happened many times that teams could not repeat their lap times from the Barcelona winter testing over the course of the Spanish GP despite to the developments because temperatures increased significantly.
The change in altitude has an even bigger effect on the internal combustion engines. On normally aspirated engines, an increase of 100m of altitude means approximately one per cent drop of performance of the engine. It has less oxygen for combustion, so the power output decreases.
However, with the introduction of turbocharger, the situation has changed. The turbo can balance the drop of air pressure out as it can force more air into the combustion chambers. That can be achieved because at other places some air is unnecessary and is released through the ‘wastegate’. That extra air can be used at higher altitude.
That means, however, that the turbo has to work much harder than usual.
Battling with overheating
Another aspect which engineers have to take into account when they prepare the cars for the requirements of the Mexican race track is the cooling. Many systems of a modern F1 car is cooled with air. Brake cooling, engine cooling, gearbox cooling are all dependent on the air. As the air is thinner, engineers have less air to work with.
That forces engineers to open up the car more than usual. They have to use bigger brake ducts, inlets to keep every air-dependent systems at their operating level in terms of temperature.
Big wings despite long straights
Downforce levels are also impacted by the higher altitude. F1 cars stand out with their incredible downforce which enable them mesmerizing cornering speed. Downforce is generated by the interaction of the aerodynamical parts of the car and the air. The change of air density has a huge effect on the amount of downforce generated. The thinner the air is, the less oxygen it contains. The thinner air leads to less downforce.
The Autrodromo Hermanos Rodriguez track has a very long straights which would indicate that engineers opt for smaller wings and smaller wing angles. However, the less downforce induced by the thinner air forces them to use bigger front and rear wings in a bid to achieve a relatively stable car in the mid-to high speed corners of the circuit and in the difficult braking zones. Despite to the bigger wings, top speeds are almost on the same level of the values achieved in Monza because the thin air leads to less drag.
Physically demanding race for the drivers
The high altitude is also a challenge for drivers. That means air has less density which makes every physical activity tougher. However, as the track has a straight which it the second longest one currently in F1, drivers have some time to relax between the technical parts of the circuit.
“So it’s one of those races where the fitness is important and it’s one of those I’ve worked towards. But it’s OK because there are long straights also to relax – so it’s not the toughest race of the year,” said championship leader Nico Rosberg.
Home hero Sergio Perez agrees the physical aspect is important in Mexico, but there are more demanding tracks on the calendar.
"Whatever you do, not only racing, running, whatever activity you do, you feel it a lot more. The circuit probably helps us with the layout. It has one of the longest straights in the calendar so physically it’s not one of the toughest: we’ve been through those already: Singapore, Malaysia – but it’s quite demanding as well, the race here,” said Perez.