The consequences of Mexico City’s high altitude for drivers and F1 cars (2286m altitude)

The Mexican Grand Prix takes place this weekend at an altitude of 2286 meters. At high altitude, the air density decreases, which results in several consequences in fluid mechanics and mechanics. If the teams arrive with slightly different single-seater cars, the drivers themselves must also prepare.

Thinner air at 2286 meters high

The density of air varies according to several factors such as temperature, pressure, and altitude. At sea level, the density of air is about 1.225 kg/m³ under standard conditions (temperature of 15 °C and pressure of 1013.25 hPa). As altitude increases, the density of air decreases exponentially. At approximately 3,000 meters of altitude, the density will be around 0.9 kg/m³, and at 9,000 meters, it will decrease to around 0.4 kg/m³. This decrease is primarily due to the decrease in atmospheric pressure and to a lesser extent, the variation in temperature.

As a result, if the proportion of the air mixture (Nitrogen 78%, Oxygen 21%) remains relatively the same, in each liter of inhaled air, there is a smaller quantity of gases. Therefore, there will be less Nitrogen and less Oxygen. It is a bit like if, for one breath, the supply of gases was equivalent to 3/4 of a breath.

Prepared pilots

The drivers are physically prepared to breathe at high altitudes so as not to be affected during this particular Grand Prix. They undergo training prior to the Mexican Grand Prix with slightly reduced air quantity in order to produce more red blood cells, thus transporting more oxygen in their bodies. The heart also needs to beat faster to function more efficiently.

Being efficient in high altitude conditions also allows the body to function better at lower levels. Therefore, elite athletes regularly replicate conditions where oxygen deficiency is felt in order to train throughout the year.

Less powerful engine explosions

With each explosion of the V6 engine, the produced energy is slightly weaker. Indeed, the gas/petrol mixture is less dense for the same space. The cylinder capacity of F1 engines is 1600cc, so when this space is filled with the mixture before the explosion, logically, there is less nitrogen and oxygen. Therefore, this mixture is supposed to explode less. However, the engine developers have a little secret: the turbocharger.

The turbocharger compresses the air in the 1600cc engine, thus allowing for a slightly more efficient combustion.

More stressed turbos

To compress more air into the engine, the turbochargers must therefore work faster. However, the engineers are limited in order to remain within the reliable operating range in terms of turbo speed. The engines can therefore handle more turbo pressure, but not too much. This is a real technical challenge demanded of F1 engineers.

A lower air resistance.

Englisg The engines produce slightly less energy but on the other hand, they are also less hindered. Indeed, the resistance of the air, which is less dense, is lower. Compared to a lower circuit, the F1 therefore has less difficulty penetrating the air, theoretically allowing it to go faster in a straight line.

Less support

As the air is less dense, and provides less resistance to the cars, it also loses the ability to generate downforce. Therefore, the floor is slightly less efficient, as well as the front and rear wings. The entire car is therefore expected to behave differently.

So in Mexico, despite the fact that the circuit is quite fast and would theoretically require little downforce, the wings are as large as in Monaco.

Cooling the engine and brakes is more difficult.

Single-seaters are subject to greater difficulty in using air as cooling. Thus, the engines, which are cooled by radiators in the side pods, are more difficult to cool. This is also the case for the brakes, which are always ventilated, but have more trouble dissipating heat. The brake scoops here in Mexico are therefore larger, and the engine air vents are also much more open. The engine covers are sometimes even fully open at the top.

Comparison of engine covers of F1 cars in Mexico.