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Tuesday, April 16, 2024

The Hair-Raising, Record-Setting Race to 331 MPH

When SSC North America boss Jerod Shelby reached race driver Oliver Webb after Webb attempted to set a speed record in the company’s new 1,750-horsepower SSC Tuatara, the 29-year-old Brit was sitting on the ground with his head in his hands. “He looked at me and said, ‘Jared, I’m done. I’m never doing this again,’” says Shelby. “During the drive a blast of wind had knocked him completely over to the side of the road, onto the rumble strips. He was shaking. His first baby is due soon, and he was all emotion.”

Shelby assumed the wind had ruined the October 10 attempt to break the current production-car speed record of 277.9 mph, set by a Koenigsegg Agera RS in 2017 on the same 7-mile stretch of Nevada State Route 160 near Las Vegas. Last year, Bugatti set an unofficial record of 304 mph with an enhanced version of the Chiron, and SSC wanted to beat that too. But at those speeds, a puff of wind that wouldn’t lift a paper umbrella from a piña colada on the Vegas Strip could send any hypercar spinning into the desert scrub, with potentially deadly results.

But the driver looked up at him and cracked a smile: “I saw a big number on the display.”

In fact, it was bigger than Webb thought—and far bigger than what the team itself had expected. The last time Webb had glanced at the speedometer, he was hammering along at 310 mph, and the supremely aerodynamic machine was still accelerating hard. At that point, though, he really had to concentrate. “We were covering one and a half football fields each second, so I needed to keep my eyes on the road,” Webb recalls, wryly. “My vision stayed far in the distance, and the dotted white line became solid, which was the weirdest thing. When I finally decided to lift off and back down to a safe speed, I looked down and was still doing 280 miles per hour.”

Nerves aside, he had pushed through the crosswind and achieved what he was hired to do. After the satellite data from the onboard GPS system had been analyzed—the devices tracked two runs in opposite directions and calculated the average—Webb’s last dash came in at a staggering 331.15 mph. The first run speed was 301.07 mph, making the final verified average 316.11 miles per hour, handily beating both the Koenigsegg and the Bugatti records and cracking the metric milestone of 500 kilometers per hour just for good measure. In addition, the morning’s effort garnered records for the fastest flying mile on a public road (313.12 mph) and the highest speed achieved on a public road (331.15 mph). For Guinness to certify the achievement, the defacto keeper of world records sends two sanctioned witnesses and stipulates a variety of criteria, including production-vehicle specifications, the use of street tires and non-race fuel, and the averaged runs, to account for wind and road-grade factors that might favor a particular direction of travel. The record is likely to stand for a while, but it’s not unbeatable. Both Hennessy Performance Engineering and Koenigsegg are working on new 300-plus mph cars that could punch through yet again—though of course SSC would only need a calmer wind day to boost its time.

Ultimately, Webb says, the limiting factor on the road that morning wasn’t the car—its 5.9-L twin-turbo V8 was still good for at least another 20 mph, SSC engineers estimate—but the conditions. “We didn’t have six lanes on a test track to play with,” says Webb, who competes in multiple race series, including Le Mans and the World Endurance Championship, in addition to being a test and stunt driver. “This is two lanes, and if you get pushed over one lane you only have 6 inches before it’s game over. So it was me deciding to back out of the run. In ideal conditions, we could have gone faster.”

The effort is the culmination of a 10-year development process for the $1.6 million Tuatara, which succeeds the company’s SSC Ultimate Aero. That car had set the record in 2007 for fastest production car, with a speed of 256.18 mph. SSC approached the design of the new car with the record in mind, Shelby says, and the team paid particular attention to the engine—developed in collaboration with Nelson Racing Engines—and aerodynamics, as you’d expect. They had to be more than just good enough to keep the car on a racetrack: The car needed to be slippery enough for high-speed straight-line driving and able to generate enough downforce to stick to the pavement, yet it still had to look great to collectors and the hypercar-admiring public.

That challenge fell to designer Jason Castriota, whose background includes time at Italian automotive design houses Bertone and Pininfarina, where he contributed multiple Ferrari and Maserati production and concept vehicles. He says his chief challenge with a car engineered to exceed 300 mph included managing the airflow both externally and internally, the latter due to the tremendous heat generated by the engine. Too many radiators and extra cooling fluid would increase weight, so Castriota created a network of channels that funnel air into and out of the car. The team adopted an extended wheelbase, an ultracompact engine configuration, and a passenger compartment that resembles a capsule, all in the service of controlling airflow for cooling the engine and brakes, increasing downforce, and minimizing drag. The car has a coefficient of drag of 0.279, which itself is a record for its class—a Jeep Wrangler scores a chunky 0.454 by comparison.

The total downforce at 312 mph—the maximum they simulated—was 770 pounds. Think of downforce as the aerodynamic opposite of the lift generated by an airplane’s wing, and Shelby estimates it would have been well over 800 pounds at 331 mph, Webb’s top speed.

Aerodynamic balance is also essential, in that it determines the “center of pressure” in the car—where the car is pushing down the most. That should be happening directly behind the driver, but in early iterations of the car, computer simulations indicated that at high speed, over 300 mph, most of the downward aerodynamic force was occuring 10 car lengths ahead of the vehicle, as it pushed air forward while moving through it. “We had to claw back our center of pressure to get it where we needed it to be,” Castriota says. “It was a million little adjustments and reshaping of the car to walk it back.”

An automatically adjusting rear spoiler helped as well, contributing to a final aerodynamic balance of 37 percent of the downforce at the front of the car and 63 percent in the rear. On Webb’s drives above 300 mph, the balance of air pressure increased the car’s stability, while its deliberate rearward bias increased its resistance to nosing forward during braking, as happens when the balance shifts instantly from rear to front as soon as the driver lifts off the throttle. Even still, Webb says he backed off gently to manage the deceleration, as doing so too quickly could still destabilize the car. The aerodynamics are so precise, in fact, that Webb decided not to shift into the final gear of the computer-controlled, single-clutch, seven-speed rear-drive transmission. Doing so, he notes, would have shaved a few miles per hour off of his current speed that he would have to reclaim before surpassing again and continuing on, due to the immense frontal air pressure at that speed.

Shelby says that the weeks leading up to the record attempt were spent doing “low-speed” test runs below 250 mph near the company’s headquarters in Washington state, and inspections of all systems from the Michelin-supplied tires to the onboard electronics managing the powertrain.

A potential 11th-hour deal-breaker did emerge in the engine, when engine manufacturer Tom Nelson noted that the exhaust gas was 200 degrees too hot, a condition that would have required them to scrap the record attempt and design a different turbocharger. Engineers discovered it was due to a timing issue with the ignition coil, which was causing the spark plugs to fire a few milliseconds too late. Nelson’s team discovered that tuning resistors in the coil to sync up the ignition timing solved the problem, and the record attempt could proceed.

The team also fretted about the road surface—recently repaved, fortunately, and absent the “crowning” some roads have for runoff, which could cause a low-clearance car like the Tuatara to bottom out at 300 mph—and, prophetically, the crosswind conditions. Oh, and anachronistic livestock management techniques, as well. “We did some testing down in Nevada, and there was actually a shepherd, on a bicycle, running sheep across the road,” Shelby says. “I didn't even know they did that anymore. But there they were.”

No sheep materialized ahead of Webb that Saturday morning, and his runs were affected by nothing but the crosswind. He describes the car at top speeds as possessing a “floaty and light” feeling at 330 mph, signaling harmony between the suspension, aerodynamics, and powertrain. The only other sensations were the bracing acceleration of the roaring engine and the warping of time and space as his attention drifted farther and farther down the road.

Updated 11/2/2020 7:08 ET: After automotive YouTubers Shmee150, Robert Mitchell, and Misha Charoudin, among others, analyzed available footage of the SSC Tuatara's speed record attempt, flagging potential inconsistencies between the footage and the GPS data provided, SSC has decided to redo its record attempt, at a date to be determined.

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