Mexico's altitude will test engines for NASCAR Cup, Xfinity Series teams this weekend

NBC Sports

3 hours ago

Drivers and teams will have more than each other to contend with when the NASCAR Xfinity and Cup Series race this weekend at Autódromo Hermanos Rodríguez in Mexico City.
They'll also have to contend with the elevation. The road course is about 7,500 feet above sea level — the next highest track in NASCAR is Las Vegas at about 2,000 feet elevation.
The higher elevation means thinner air. Air plays a key role in horsepower and cooling and those will be significant issues for teams.
Doug Yates, president and CEO of Roush Yates Engines, estimates that the thinner air could reduce horsepower as much as 20% for the 670-horsepower Cup engines.
Danny Lawrence, long time engine builder for Richard Childress Racing and its director of the Xfinity Series and vice president of alliance operations, said maximizing horsepower is challenging at such a high altitude.
'You've got to fool the engine to make it think that the conditions are better,' he told NBC Sports.
#NASCAR races this weekend at Autodromo Hermanos Rodriguez in Mexico City. The area is about 7,500 feet above sea level (Charlotte, NC, home to the teams is at 751 feet above sea level). Daniel Suarez talks about the challenges of competing at high elevation. pic.twitter.com/N2YzUAxQyQ
Daniel Suarez said the horsepower reduction will be minimal for drivers.
'I don't think you have to drive different, but the cars are going to have more mechanical grip especially on the exit of the corners because you have less power,' he said. 'We're going to lose like 80 to 100 horsepower. That's a lot. … But at the same time, in the high-speed corners, we're going to lose a lot of downforce. We're going to lose a little bit of everything.'
Racing at such elevation is new for the Cup Series. The Xfinity Series raced in Mexico City from 2005-08. The series averaged nearly seven engine failures per weekend (practice and the race) the first three years. The final year racing at Autódromo Hermanos Rodríguez saw no engine failures during the weekend.
'I would say we're more concerned about the cooling and the components and the other things we have to ensure are properly set up,' Yates told NBC Sports.
NASCAR will allow each manufacturer to have two sets of hood louvers to run during practice Saturday to see which best cools the engine. Each manufacturer will select which hood louver it will use and all of its teams must use the one selected on its cars.
Dustin Long,
'The problem we have with the engine is the caution laps,' Trent Owens, crew chief for AJ Allmendinger, told NBC Sports. 'It gets so hot under the caution laps, more so than the green laps.'
Under green flag conditions, the cars are at higher speeds and can get more air to cool. The slower speeds under caution means less air gets to the engine to cool it. As engines start to overheat, several problems can ensue.
'What happens with the engine management software is it goes into protection (mode) if you don't get it cool enough before the restart,' Owens said. 'So you're trying to prevent that. It doesn't shut the engine off, but it starts feeding it fuel and changing the timing and stuff like that where you lose horsepower.
'So, just having that stuff right is probably our concern that we normally don't have to worry about at any (other) event.'
With NASCAR's rule that engines must run two races, most of the engines that will run in Sunday's Cup race will be that engine's second race.
Yates said a lot of the Ford engines for the 2.42-mile road course in Mexico were run earlier this year at Martinsville, a half-mile short track.
Yates says the two courses share some similarities so that running one engine at both tracks makes sense.
'We shift at Martinsville every straightaway, every lap,' Yates said. 'So the power curve actually shifted up quite a bit from years ago. As the engine group, we have the opportunity to change the intake manifold and the exhaust system today, so we can tune around the base engine and have power lower RPM range or higher RPM range with those two tuning tools.'