Enlarge /. This photo was actually taken during the February Daytona 500, which uses the Daytona International Speedway's 2.5-mile tri-oval. But there aren't any photos of production cars doing the 3.6-mile street course yet, and that's what the cars would still look like as they cross the start-finish line and prepare for the sharp left turn into the brake infield.
This is one hell of a weekend for racing. In Indianapolis the drivers qualify for the 500 next Sunday. The WEC saw action in a very wet spa this morning. Formula 1 drives in Catalonia in Spain, the most popular test track. And the NASCAR Cup series is trying something new.
It was supposed to be spending this weekend in Watkins Glen, New York. But 2020 made it, and so the scenic route in the Finger Lakes, once home to Formula 1 in the USA, is outside the borders. NASCAR will be racing at Daytona for the second time this year. And for this visit, Stock Cars will use a layout better known to fans of the annual Rolex 24 Endurance Race for Sports Cars as the 4km Tri-Oval.
Almost. The 750 hp (560 kW) production cars used in NASCAR's Cup series are much more powerful and have much lower aerodynamic drag than the prototypes at 290 km / h and the GT vehicles that drive in the Rolex 24 at 48 km / h faster than this sports car. And at 1,564 kg (3,450 lbs), they have significantly more mass that needs to be controlled.
"When they pulled into Turn 1, they would have to go 338 km / h and slow down to 50 to get around the corner and we quickly realized that that probably wasn't going to happen for 65 laps here," explained John Probst, Sr. Vice President for Race Innovation at NASCAR.
As a result, just before the start-finish line, drivers will find an additional pair of corners in the form of a chicane, which slightly expands the layout to 5.81 km (3.61 miles). Creating a speed loss chicane isn't as easy as sliding a few cones onto what is normally on the speedway's skid pad. Probst's team turned to simulators to make sure the profile for today's Rounds 13 and 14 was working properly.
"We tried to set it up so that the cars enter at a speed of 290 km / h," said Probst. "And then we wanted to keep the car somewhere near 113 km / h in the middle. So we configured the geometry of the chicane so that the speed increases to about 70 in the middle of the corner."
However, this new chicane means that one lap of the Daytona street course now includes three major braking events – Turn 1, the bus stop chicane (turns 9 and 10), and now this new final chicane. So expect brake management to be the order of the day in Sunday's 378km race. For road courses, Cup series production vehicles use 12.7-inch cast iron rotors with six-piston brake calipers at the front. You might expect the big challenge to be keeping the brakes from getting too hot, but in fact, teams may have the opposite problem.
"One of the unique features here is that we're going to get really high speeds," Probst explained. "That means a lot of airflow to the brakes. The brute force approach of" more air is better to cool brakes "would probably work if it were all twists and turns and brakes." There are three long high-speed stretches between the 14 corners of the street course.
Don't let the rotors get too cold
"We will have three very important braking events that will obviously bring a lot of temperature to the brakes," explained Probst. “But then you come out of Turn 6 – that's the return to oval Turn 1 – and you go all the way to the bus stop. If we look at the speeds here, we'd really expect them to be in the 190s with the package now with high downforce, and that means they'll cool off a ton when they go down the bus stop. They don't get cold in the sense of freezing cold, but cold in the sense of brake discs compared to where they are on the bend and they'll do that a couple of times per lap, which will crack the rotors. "
That probably doesn't mean the brake discs will break. "When you've got bugs, it's uncommon for the cracks to be so high that something actually falls apart," Probst said, but repeated hot-cold cycles could create driver handling problems. “But what's bad is when they glow red and then glow really cool and then glowing hot and then really cool – after all, they reach the point where the geometry changes in the rotor itself, typically in the areas where it is the coils would be attached and things like that, "he said. And in contrast to a long-distance car in a 24-hour race, no fast braking work is provided for a production car.
The advantage for the fans is that longer braking zones offer more opportunities for overtaking. For how much longer? For braking at the bus stop, Probst told me that NASCAR, which is wrong on the conservative side, put up four additional distance markings this weekend.