The Pirelli World Challenge series offers a terrific platform for manufacturers to market their production-based cars. Porsche, Cadillac, Audi, BMW, Volvo, Acura, Mazda, Chevrolet and others have …
Venerable Vet
Photograph by Mark Weber
Despite their reputation as a luxury-car brand, Cadillac is not new to racing. American sportsman Briggs Cunningham ran Cadillacs at Le Mans in the early 1950s. Fifty years later, factory-backed prototypes returned to the famed French track.
A bit closer to home, Cadillac launched a World Challenge program in 2004 using Pratt & Miller-built CTS-V sedans. The program was a success: Cadillac claimed both manufacturer and driver titles, and during this time sales of the street version increased dramatically.
When the market tanked and GM filed for bankruptcy, Cadillac halted their racing efforts for a couple of years. In 2011, they returned to World Challenge with their new CTS-V Coupe. The shape was updated, but the guts could be called evolutions of the previous car’s.
Cadillac Racing campaigns two GT-class entries for GM factory drivers Andy Pilgrim and Johnny O’Connell. The time away from the sport didn’t slow them down: Cadillac took second in last year’s manufacturer point race, while O’Connell finished second in driver points. After this year’s St. Pete opener, Cadillac was leading the manufacturer points race.
Following in the footsteps of Cadillac, Kia is the latest manufacturer to compete in the World Challenge GTS program. Their weapon of choice is their Optima family sedan.
Kia’s racing roots don’t go back nearly as far as Cadillac’s. While Dave Wolin campaigned some Kias back in the ’90s, the brand’s modern era of racing really started in 2009 with a factory-backed Grand-Am Koni Challenge effort. Two years later, Kia had won the drivers championship and team title.
Their Grand-Am program will be joined by a World Challenge effort for 2012. “Kia recently remade their product line and brand,” says Scott McKee, director of public relations for Kia. “The Optima is a fun, sporty, top-of-the-line car, and we can highlight this in motorsports, similar to other brands.”
As McKee explains, the brand looked at the rules packages for different series and determined that World Challenge had the perfect competitors, race format, media package and rules for the Optima. In 2012, Kia will campaign two World Challenge Kia Optima cars in the GTS class, one for five-time World Challenge champ Michael Galati and another for Colin Braun. At 23 years old, Braun has already claimed NASCAR rookie of the year honors and is the youngest driver to stand on the Le Mans podium.
Cadillac Racing: Building the CTS-V Coupe
Photograph by Sahar Hassani
In late July of 2010, Steve Cole, program manager for Pratt & Miller, received the green light to begin building the Cadillac CTS-V Coupe racer for the 2011 World Challenge Series. The renowned race car builder had less than eight months to assemble, develop and test the new vehicle before the season opener, a far cry from 2003 when the factory spent a year developing the CTS-V sedan.
The team was able to save some time, though, as the new World Challenge racer is a progression of the previous one. The basic roll cage and suspension configurations, for example, are both carry-over items.
As per the World Challenge GT-class rules, the OEM-type suspension must be retained, but pickup points can be moved. In the Cadillac’s case, the chassis cradles were raised in order to drop the car itself closer to the ground. The floor remains in the original location, but Pratt & Miller had to redo the inner and outer fenders to accommodate the new ride height. “It’s a lot harder than it sounds,” Cole adds.
Pratt & Miller had the luxury of starting with bare bodies in white. While the race cars retain the basic street car’s tub, they have been reskinned in carbon fiber.
Photograph by Sahar Hassani
“Everything on the body is carbon fiber except the roof,” clarifies Cole. This major modification allows the race car to weigh in at the mandated 3200 pounds, approximately 1000 pounds lighter than its street version.
The tail of the revised body is capped with a wing hanging from what is called a swan neck. Look at the back of Audi’s latest Le Mans racers and you’ll see something similar.
GM Powertrain handled the development of the 6.2-liter, LS3-spec V8 found inside the Cadillac. Katech Motorsports, supplier for such GM factory road racing efforts as the Grand-Am Camaro GT.R and FIA Corvette C6.R GT1, assembled the engine and manages that part of the program.
Unexpectedly, the race engine makes less power than the one found in the street cars: a claimed 500 horsepower for the World Challenge Cadillac vs. the 556-horsepower rating for the supercharged V8 powerplant found in the latest production CTS-V.
Photograph by Sahar Hassani
The transmission is new for Cadillac, though. “The gearbox includes a no-lift shift that allows the driver to shift without lifting off the gas,” Cole adds.
The idea behind the World Challenge formula is to keep the cars evenly matched, although some are stronger than others at certain kinds of tracks. While the Cadillac may be down on speed and horsepower compared to the Porsches and Volvos, for example, the CTS-V excels in high-speed corners.
“We have the longest wheelbase in the GT class,” Cole says. The Cadillac performs best at fast, flowing tracks like Road Atlanta and Mosport, although this year it had a strong showing within the confines of the St. Pete street course.
From the Driver's Seat: Andy Pilgrm
Andy Pilgrim drove for Cadillac Racing during their first foray into the World Challenge series in the mid-2000s. When Cadillac got the band back together, he was asked to rejoin the team.
The CTS-V Coupe is very similar to the first-generation race Cadillac CTS-V race car, Pilgrim explains. The new car has the same weight, the same wheelbase and similar power.
“Driving-wise, the biggest difference is the gearbox,” he says. “We have a sequential, no-lift shift, whereas before we had an H-pattern box. The new one is much faster and in line with all the other cars.”
The new CTS-V coupe race cars debuted last year, and the team made continuous tweaks to match the rest of the field. “We are now comparable on straight-line top speed,” Pilgrim reports, although he adds that the Cadillac’s higher base weight hurts off-the-corner performance. That extra weight and longer wheelbase also hinders transitional performance; Mid-Ohio is not the team’s strongest track, Pilgrim confides.
The long wheelbase isn’t always a detriment, though. “We can use curbs that can upset other cars,” he says. “A longer-wheelbase car will tend to be more stable over bumps in corners.”
One of the biggest changes that occurred during the hiatus is the series’ move from street-based, R-compound Toyo Proxes to Pirelli racing slicks. World Challenge made the sweeping change for the 2011 season, and the purpose-built race tires further distance the Cadillac from its roadgoing brethren.
“We are faster than Grand-Am GT everywhere we go and not far behind the ALMS GT cars,” he says. “As a race car driver, I love the Pirelli race slicks because they make the car so much faster.” The team figures 2 seconds per mile can be credited to the new rubber.
Pilgrim’s favorite thing about Cadillac’s return to the track? “The noise of the big V8,” he smiles. “It doesn’t sound like anything else out there on the track.”
Fledgling Fighter
Photograph by Mark Weber
Kia Motors America doesn’t exactly have a long, established racing heritage. They never ran at Le Mans, and their cars have yet to compete at Sebring.
In fact, their current arrangement with Kinetic Motorsports—their go-to racing partners—dates back to just 2009. The pair campaigned the then-new Kia Forte Koup in the Grand-Am Koni Challenge, an endurance series for mildly modified street cars.
It took only two seasons for the Kia to taste a championship, winning last year’s manufacturer title. That program returns for 2012, but it’s not the automaker’s sole racing effort: They’re also campaigning a pair of Optimas in the Pirelli World Challenge series.
Like the latest Cadillac racer, this one came together quickly. “We received the Optima the third week in October and had only six months to develop the car for the first race in St. Pete in March,” explains Russell Smith, Kinetic’s team manager.
Although the GTS-class Optima is closer to stock than the radical Cadillac GT, it needed plenty of work. GTS is dominated by V8-powered, rear-drive pony cars plus a pair of well-developed Acura TSX sedans.
“The body in white was not available for the Optima, so we began with a fully loaded car that had to be stripped down,” Smith explains. The team quickly gutted the car to remove unneeded parts and sent off the shell to soak in acid for a few days. The acid bath removed the seals and paint and allowed the team to weld and stiffen the shell.
Once the shell returned to the Kinetic shop in Atlanta, the roll cage was installed and the shell seam welded. Besides increasing safety, the goal here was to create a stiff chassis—one that was tested on a kinematics and compliance rig in Charlotte. The system measures force vs. movement distance of the chassis and suspension, and the data shows how the car will react to real-world situations, all before putting a tire on the track.
Photograph by Sahar Hassani
The turbocharged inline-four, 2.0-liter engine is as delivered from the factory—well, kind of. “The Optima’s motor is stock, but we were able to add forged pistons for durability. We also inserted stronger connecting rods and fortified the main bearing caps to better support the crankshaft,” says Ed Senf, engine calibration and data acquisition engineer.
Which parts are stock? The camshafts, fuel injectors, intake manifold, engine block and cylinder head are all factory Kia parts. “I’m impressed with Kia’s stock parts,” Senf adds. “They have proven to be robust for racing.”
Then there’s the turbocharger, a forged Garret GTX3071R unit hooked to a custom intercooler setup; the Optima’s World Challenge tech sheet dictates that it be placed inside the engine bay. World Challenge officials also limit the race Optima to about 20 psi of boost, and the team claims 360 horsepower along with 300 lb.-ft. of torque, a good bit more than the 274 horsepower and 269 lb.-ft. of torque produced by the factory engine.
Preparing the electronics proved to be the team’s greatest challenge and worst nightmare, with the job requiring plenty of work hours. “The factory ECU wants to control emissions, control fuel economy,” Senf explains. “Its goal in life is not to go fast all the time.”
A Bosch Motorsport MS 5.0 engine control unit solved their problems. It’s a powerful, fully programmable ECU designed for top-tier professional motorsports. “It has tons of processing power,” Senf says, “and it doesn’t limit us in the future.”
While the MS 5.0 computer is the brains of the operation, a Bosch Motorsport HPI 5 injector driver does the heavy lifting. The Optima is powered by a direct-injection engine—the fuel squirts directly into the combustion chamber, not the intake tract—and a standard ECU can’t drive the system’s high-pressure pump or fire the injectors against the cylinder pressures.
Direct-injection engines also require very precise injector timing, another reason for the injector driver. The injectors on a standard, port-injected engine usually have 10 to 16 milliseconds to squirt the fuel. On a direct-injection engine, that window of opportunity is cut down to 5 to 6 milliseconds.
Photograph by Sahar Hassani
Since Kia and Acura are the only front-wheel-drive cars in the GTS class, the SCCA allows them to use sequential gearboxes. The Kia has to run an aftermarket box anyway, since the turbo engine isn’t offered by the factory teamed with a manual. The team runs the popular Xtrac, a unit that’s purpose-built for the rigors of road racing.
The GTS cars cannot take advantage of the radical bodywork changes found in the GT class, but the Kia still received some add-ons. Both a rear wing and front splitter provide downforce, while a lightweight, carbon-fiber hood is allowed.
The rest of the car retains the stock steel, although it has shed some unnecessary weight. The doors, for example, have been hollowed out so just the outer skin and a bare frame remain. The race Optima weighs in at 2900 pounds without the driver, about 500 pounds lighter than the street version.
As a result of the tight build schedule, Kia had very little time to test prior to the series’ first race at St. Pete. They had a lot of enthusiasm, however, and both cars ran mid-pack.
Michael Galati finished seventh and 10th during the doubleheader weekend, while teammate Colin Braun took 14th and 16th after rebounding from racing incidents. “There were a lot of banzai moves out there,” he explains. “Street courses typically breed yellows. Little mistakes create a big pileup.”
Despite his disappointing finishes, Braun was impressed with the Optima: “Many manufacturers here have been racing several years; we were competitive right out of the box. It’s a great testament to the team and Kia.”
Perhaps better finishes are around the corner. “We just need to make little refinements to be more competitive,” he adds.
From the Driver's Seat: Michael Galati
“I’ve raced many cars in this series, including the Audi, Mercedes, Mazda and Volvo,” explains Kia Optima pilot Michael Galati. “The guys are very professional and expectations are very high. They finished the car on Tuesday and began racing on Thursday, and nothing broke down this weekend.”
The Optima’s greatest strengths? The car’s handling and braking ability, two factors that improved as the car shed mass. “They did a great job of keeping the weight down,” he adds.
Galati compares the Kia to the Mazda6s that once dominated the old World Challenge Touring Car class—back when the rules allowed Touring Cars to make some 300 horsepower from hypertuned, naturally aspirated, small-bore engines. The Kia, though, pretty well matches that performance with a more manageable package.
While there is some development work left to be done, Galati says he’s thrilled at the prospect of winning a manufacturer title for Kia. “The strength of the Optima is the whole package,” he says. “It includes the car and team. We are running a four-cylinder turbocharged car against some V8s and doing very well.”
He’s also a fan of the street version: “The Optima is a powerful, durable car that offers a 100,000-mile warranty for its street version, and it’s made in the USA. It’s exciting to be here, competing at this level with Kia.”
Kia may be new to motorsports, but they have plenty brewing for 2012. In addition to their World Challenge and Continental Tire efforts, Kinetic is also building B-Spec Rios. This relative upstart hasn’t wasted much time honing in on our world.
What Is World Challenge?
Today’s Pirelli World Challenge series can be called the spiritual successor of the Playboy United States Endurance Cup, a long-distance series for mildly modified production cars that debuted in 1985. The format and marketing partners have changed over the years, and the current setup is big on excitement: standing starts and TV-friendly, 50-minute races.
The series is now composed of four separate classes of competition: Grand Touring (GT), Grand Touring Street (GTS), Touring Car (TC) and, new for 2012, Touring Car B-Spec. Touring Car B-Spec will compete in select races during the season.
Photograph by Mark Weber
The GT category features high-end sport and luxury cars that can make more than 425 horsepower. These cars are allowed some serious modifications, as the Cadillac CTS-Vs and Volvo S60s found in the class are far from stock. Other popular cars in the series include the Chevrolet Corvette, Nissan GT-R and Porsche 911 GT3 Cup.
Photograph by Mark Weber
The GTS class is a recent addition to the World Challenge formula. It encompasses front-wheel-drive cars built to the old, somewhat radical Touring Car specs as well as mildly modified cars that are in the 300-to-425-horsepower range. Think Chevy Camaro, Ford Mustang, Mitsubishi Lancer Evo, Nissan 370Z and Porsche Cayman S.
Photograph by Mark Weber
The realigned Touring Car class features mildly modified, small-bore coupes and hatchbacks that make 180 to 260 horsepower: the Honda Civic Si, Mazdaspeed3 and Volkswagen Jetta GLI.
Photograph courtesy Honda
The new-for-2012 Touring Car B-Spec class includes small, efficient cars, each one required to run a pre-approved suspension package and stock drivetrains. Cars like the Fiat 500, Ford Fiesta, Honda Fit, Kia Rio, Mazda2 and MINI Cooper are allowed to play here.
