The Stevenson Motorsports Camaro Z/28.R has been an odd success story in the Continental Tire Sports Car Challenge. It’s by far the heaviest car in the series at 3,500 lbs, but it’s won the past three races in a row, too. How do they do it? We picked the brains of the team for a while to find out.
Part of the Stevenson team’s success is the team behind it: they’re backed by Pratt & Miller, the same GM racing squad whose Corvette just won the 24 Hours of Le Mans. “The same tools used to win Le Mans—we’re using on this car,” explained Chevrolet Racing Program Manager Jim Lutz.
The two-hour, thirty minute CTSCC races must seem like a simple task in comparison!
As for Stevenson Motorsports, they started racing Camaros in Grand Am and CTSCC in 2010, after having run Pontiacs for a while. Pontiac was no more, and GM needed someone to campaign the new Camaro. Stevenson gave GM a team that was already intact and competitive, right out of the box. After the merger of Grand Am with the American Le Mans Series that became Tudor United SportsCar, TUSC’s support series CTSCC became the best option for the Camaro. The current Z/28.R won five times in its debut season last year, and is leading the championship this season.
CTSCC keeps everything just a little more stock than its bigger, longer IMSA-sanctioned sister series. One Stevenson team member said that they may see how the rules shake out for TUSC in the future, but for now, CTSCC is the team’s home. GM wanted a real-life test subject in the Camaro racing program, and much of the development work done on the Camaro Z/28.R is used to improve the street car.
The two Stevenson Camaros are surprisingly very stock. The Camaro Z/28.R is plucked right off the Camaro assembly line, then GM Racing has their way with it. It then goes on a diet down from the stock Camaro’s 3,820-lb curb weight.
The cushy interior comes out, and a roll cage, a fuel cell and other safety gear goes in.
The interior of the car should look familiar to anyone who’s peeked inside the Pratt & Miller Corvette, with a steering wheel and a custom seat just like the ones used in the GTLM car.
The engine gets a rebuild after 2,000 miles, but the internals are all left stock. There’s a series-mandated restrictor behind the throttle body that knocked its power down to 470 hp and 475 ft. lbs. of torque from the stock 505 hp/481 ft. lbs. of torque for Watkins Glen. It’s the same 7.0 liter LS7 as the street car, but in the name of “balance of performance,” the Camaro has to be knocked down a peg to be on an equal playing field with the other cars on site. An adjustable amount of ballast weight is also sometimes added to put the Camaro on an even playing field with the Porsche 911, Ford Shelby GT350R-C, and other GS-class competitors.
And oh, does it get balance of performance’d—often. That’s what happens when you win a series that seeks to give different cars the same chance to win.
“It’s like if you won the U.S. Open tennis and you now have to play with a frying pan,” explained team manager Mike Johnson. Adding weight and restricting horsepower on an already heavy car is tough to deal with, especially given that they run the heaviest car in the GS class on the same series-spec tires as everyone else.
Needless to say, the car got a few more balance of performance tweaks mandated after winning again at Laguna Seca. Not that it mattered, though.
As for the rest of the car, there’s a dual-plate racing clutch, but it’s fed into the same six-speed Tremec manual from the production Camaro.
Likewise, the riotous sound you hear coming out of these cars is also mostly stock. They keep the production headers and exhaust, which feed into dual pipes.
Most of the changes from stock are actually in the brakes and suspension, which allows the big beast to be maneuverable on track. Meaty roll bars are added to help the car handle better. Two-way adjustable struts help them fine tune the handling for each course. The front wheels are moved out just a bit to square out the setup, with 10” wide 18” wheels all the way around.
The brakes were actually downgraded to fit within CTSCC’s rules. The race car uses a 4-piston in place of the road car’s 6-piston setup. The caliper and rotor are both cooled through ducts built into the stock fog light location, as the series allows.
The steering is hydraulic as opposed to the power steering from the road car, giving better feedback while not being as grueling in a heavy car as an entirely manual rack.
Even the stock front splitter and rear spoiler stay on in race trim, as they’re actually functional, and help the big boxy car move through the air.
Those of you bemoaning the lack of real-world cars in racing should pay more attention to CTSCC.
Stevenson’s Camaros aren’t just doing well because the car is good. The drivers know they’re in one of the heaviest cars there, and drive accordingly.
“When you add weight to a car, you have to accelerate, brake and turn all that weight,” explained number 6 car driver Robin Liddell. He explained that with the Camaro, he has to find a compromise between hustling a car—where it takes advantage of a little bit of slip angle—and preserving the car’s tires. A car that slides and dances around a bit also wears out its tires faster, and the Camaro already has to haul a lot of extra weight. As there is no special Camaro tire, they have to manage wear on the same Continental tires as everyone else in the race.
Liddell said that it takes confidence and experience to allow the car to move as it wants to and know exactly how much weight transfer from side to side or slip angle is just enough. Drivers coming from prototypes often struggle to handle a car like this that doesn’t always do exactly what they want it to. Once again, more seat time is the answer to everything, especially when you’re getting used to a big street-car-based Camaro.
Naturally, I asked if he had any pointers for folks who bring big, heavy beasts to track days. We love big, overpowered cars on track like E-Class wagons, GT-Rs and, well, the Camaro, but hate seeing them get out of shape and flop into the grass. Tires and brakes, Liddell explained, are the key to keeping a heavy track car happy. Both generate a ton of heat on a big car and can fade quickly if you’re not careful. Be gentle on the tires and limit the amount of sliding you do if you’re going to be tracking a heavy car for a while. More smoothness, less drifting. Of course, you should start out slow and work your way up to the car’s limits.
CTSCC teams rely more on the driver to know what he’s doing and what’s going on around him than many of the other series in existence today. Teams can’t run real-time telemetry, so Stevenson Motorsports uses a MoTeC system to download data after the car runs and analyze various areas for improvement or determine the source of a problem. During the race, it’s up to the guy behind the wheel to figure out what’s going on with the car and keep it ahead of everybody else.
That doesn’t mean that races are completely decided behind the wheel, though. They’re truly a team effort. “A lot of the time, these races are won and lost in the pits,” explained Liddell.
Knowing when to swap drivers, tires and fuel is key. Liddell credits a good strategic call for their win at Laguna Seca, where the team anticipated the pits closing and timed their stop just right.
The last twenty minutes, though, is “where the driver earns his money,” according to Liddell. These may be endurance races, but they’re shorter, and the cars are generally well-prepared and somewhat reliable. The first two hours and ten minutes of a CTSCC race is all about putting yourself in a good position for the end. The final twenty is where the drivers all push on to the win.
Unfortunately for the race at Watkins Glen, the race ended under yellow-flag conditions, preempting that last twenty minutes of go-time. Liddell in the number 6 Camaro claimed first place before the yellow flag parade began, getting past the leading car as they went off-track with thirty minutes to go in the race. Oops! Stevenson’s number 9 entry had an ABS issue at the start of the race, and the yellow flag finish kept them from climbing any farther than fifth place at the end. Either way, there’s still a Camaro out in front, and with tough competition in CTSCC, that’s how Stevenson Motorsports would like things to stay.
Photo credits: Matt Rhoads (top), me (all others)
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