Here’s why NASCAR had to tweak Daytona road course for stock cars

At Indianapolis, drivers are qualifying for next Sunday’s 500. The WEC saw action at a very wet Spa this morning. Formula 1 is running at Catalunya in Spain, its favorite test track. And now NASCAR’s Cup series is trying something new.

NASCAR will race at Daytona for the second time this year. And for this visit, stock cars are going to use a layout more familiar to fans of the annual Rolex 24 endurance race for sports cars instead of the 2.5-mile (4km) tri-oval.

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Well, almost. The 750hp (560kW) stock cars used in NASCAR’s cup series are a lot more powerful and a lot lower drag than the 180mph (290km/h) prototypes and the GT cars that race in the Rolex 24. Which would mean approaching turn 1 up to 30mph (48k/h) quicker than those sports cars. And at 3,450lbs (1,564kg), they have considerably more mass that has to be controlled.

“As they started their entry into turn 1, they would be going 210mph [338km/h] and having to slow down to 50 to make the corner, and quickly, we got to the realization that that just probably wasn’t going to happen for 65 laps here,” explained John Probst, senior vice president of racing innovation at NASCAR.

“We tried to tune it so that the cars would enter at roughly 180mph [290km/h],” Probst told me. “And then we wanted to keep the car somewhere near 70mph [113km/h] in the middle of it. So, we configured the geometry of the chicane to get the midcorner speed to about 70.”