Why the altitude will be a huge factor at the Mexico City Grand Prix

Thinner air poses a big challenge for teams, and drivers, at the Mexico City Grand Prix

Formula 1 is in the middle of its toughest stretch of the season, a triple-header of races taking the grid from Austin, to Mexico City this week, and finally to São Paulo for the Brazilian Grand Prix. While the F1 schedule originally had two different triple-headers on the schedule, the cancellation of the Emilia Romagna Grand Prix due to flooding removed the first.

But now we are living the second.

However, the compressed schedule is not the only tricky factor facing the teams this weekend. The other? Altitude. The Mexico City Grand Prix is run nearly one-and-a-half miles above sea level, making the Autódromo Hermanos Rodríguez the highest circuit the grid faces each season.

Just as teams face challenged when heading to Colorado to play the Denver Broncos for example, F1 teams, cars, and the drivers themselves face some unique challenges this week.

“The circuit in Mexico City is characterised by the altitude; sitting 2200m above sea level means that the air pressure is low,” said Dave Robson, the Head of Vehicle Performance at Williams. “The low pressure means that despite running large rear wings, the drag and downforce of the cars is low. Cooling the PU and the brakes is also difficult, and the turbo needs to work very hard to keep the ICE running correctly.”

Ahead of last year’s Mexico City Grand Prix, Red Bull put together a deep dive into how the altitude impacts every aspect of the car. It starts with air pressure. In the thinner air, air pressure is lower, leading to reduced performance from the cars.

While today’s turbo-charged F1 cars do not see a reduction in power like we saw in earlier versions of F1 cars, which required oxygen for the combustion process, the conditions at Autódromo Hermanos Rodríguez put more stress on the turbo. This leads to cooling issues, and more potential failures during races:

Unlike their normally-aspirated predecessors, air is compressed by the turbo (which is powered electrically, from the Energy Recovery System) and forced into the cylinders under pressure. The engine can burn as much oxygen as it does at sea-level – but at the cost of the turbo having to work much harder than it does elsewhere. Increasing the rpm of the compressor obviously places more strain on the unit and leads to more failures – but it also makes it run hotter and require more cooling, which is another challenge at altitude.

So you have hotter systems requiring more cooling, which might seem simple enough until you remember that F1 cars use air for their cooling systems. At higher altitudes, there is less air, making cooling a challenge. “In terms of running the car, we’ve got to work with less air,” said Red Bull’s Paul Monaghan, Chief Engineer. “All the air-dependent systems, whether it’s brake cooling, engine cooling, gearbox, are going to struggle.”

As a result, teams are forced to open up the cars as much as possible. Bigger brake ducts and air intakes will be spotted all over the track this weekend, in an effort to get as much air into these systems as possible.

There there is the issue of downforce.

When talking with McLaren CEO Zak Brown this week, he reminded me of one of F1’s biggest truisms: Downforce is fast. “Ultimately, you wanna put downforce on the race car without creating drag. Drag is slow, downforce is fast,” explained Brown to me this week.

However, in the thinner air, downforce is harder to come by. “Performance-wise, the amount of downforce you generate is going to be substantially less,” explained Monaghan last season. As a result teams run packages that you see at slower tracks, like Singapore, with big rear wings.

But they are still running at speeds comparable to faster circuits, like Monza. Particularly on the long main straight coming out of the final turn, back to the start/finish line, and into Turn 1. In fact, during the 2016 race Valtteri Bottas, then with Williams, clocked in at 372.5km/h on the main straight (231.48 mph), the fastest speed trap during a race in F1 history.

All of this makes for a difficult balancing act for the teams this week.

Finally, there is the impact on the drivers as well as those in the garage. As we have seen this year driving an F1 car can be a grueling task. At the Qatar Grand Prix, for example, conditions combined to push drivers to the limit, with some like Logan Sargeant retiring due to the conditions, while others like Esteban Ocon admitted to vomiting during the Grand Prix.

At higher altitudes, physical activity is much tougher because again, there is less oxygen available. Pit crews will find it a bit harder to carry out their tasks, and the drivers will face challenges as well.

And while you might see NFL teams, for example, travel to Denver early to try and get acclimated to the conditions, the compressed nature of the F1 schedule makes it hard for the teams to do that well enough in advance of the race. As a result, the teams take steps to make sure drivers and team members are as prepared as they can be.

“The biggest thing we’re trying to avoid is altitude sickness,” said Brad Scanes, Max Verstappen’s physio and a Human Performance Consultant at Red Bull Racing.

“The body uses oxygen as an energy system and, above 1500m, your work capacity is reduced by about three per cent. Too much exertion makes the body try to use oxygen it just doesn’t have available, you can’t handle it, and get sick. The way to avoid that is getting out to the event earlier,” said Scanes last season. “Of course, we’d like to have two or three weeks, but it’s never going to happen. Much like the case with heat training leading into the Singapore Grand Prix, we do what we can in the time available – and even two or three days is enough time to get that adaption process started.”

In all, a whole host of challenges for the teams, and the drivers, to take on this week.