Serie de tecnología Chevy, parte 3: dinámica de la conducción
Marchando cómodamente entre la innovación y la locura
It's easy to measure horsepower and it's simple to measure fuel economy. We can gauge interior and cargo space in cubic feet, engine size in cubic centimeters, transmissions by the number of speeds, curb weight in pounds, and length, width and height in inches. But how do you measure a vehicle's driving dynamics? We can offer lap times, skid pad data, braking distances and turning circles, but ultimately, only one calibration counts, and it's measured by the seat of your pants. Is the car fun to drive? There's no argument that safety and stability play enormous roles in how Chevrolet engineers benchmark the driving dynamics of our products. The past decade has seen dramatic advances in suspension development, brake components, tire composition and - arguably most important - electronic aids that enhance multiple aspects of ride and handling under normal, emergency and high-performance conditions.
Short of putting you in the driver seat for a test drive - and that's something any Chevrolet dealer will be happy to do - we've done the next best thing: Brought Conrad Grunewald, a professional drifter who races a Chevrolet Camaro SS, and Tony Roma, program engineering manager for the 580-horsepower Camaro ZL1, to Willow Springs International Raceway in California to demonstrate the capability of some of Chevrolet's latest technology and how it enhances driving dynamics. Individually, technological innovations can be compelling, but when they are properly integrated, they can result in a downright revelation. That's what makes a car like Camaro ZL1 so versatile and driver-friendly - and we work hard to engineer with the driving spirit of our high-performance models in every new vehicle with a Chevrolet badge, be it sports car, sedan, pickup or SUV.
"ZL1 is great at everything, and we're very proud of that," said Roma. On the drag strip, Chevrolet testing has seen quarter-mile times in the upper 11-second bracket. Plus, Roma said, "You can also take it to a road course, where it's balanced, handles well, and does exactly what you want - including lapping Virginia International Raceway's 'Grand Course' in under three minutes. And yet the ZL1 is smooth and sophisticated enough to use as a daily driver."
Quick and consistent quarter-mile times for the manual transmission version of the ZL1 are due in part to electronic launch control, which automatically modulates engine torque for the best possible acceleration without excessive wheel spin. When the driver holds the throttle to the floor, the system determines the proper engine speed, which it selects based on several parameters, until the driver releases the clutch. Besides the ZL1, it's offered on all manual transmission Corvettes and the manual transmission.
Camaro SS. Launch control is one of the technologies managed by the Performance Traction Management (PTM) system on ZL1, also offered on Corvette ZR1 and Z06 - not surprising since Corvette pioneered the system. PTM optimizes traction for greater and more consistent on-track performance, integrating Traction Control, Active Handling and Magnetic Ride Control™ systems to enhance racetrack driving consistency and overall performance. When full throttle is applied upon exiting a corner, PTM automatically manages acceleration dynamics.
StabiliTrak® Electronic Stability Control — one more feature that first appeared in the Chevy lineup on Corvette — is a compelling example of “trickle-down technology,” meaning that as the system is perfected, it becomes more cost effective to produce, and now it’s standard across most of the Chevy lineup for 2012, even on the upcoming 2013 Spark. StabiliTrak uses individual wheel braking and power reduction to help the driver correct understeer and oversteer.
On SUV and pickup models, it senses, and addresses, a potential rollover situation. Also, Tahoe LS and LT get the Premium Smooth Ride Suspension, while the LTZ comes standard with the sophisticated Autoride® Suspension. While you may not associate electric-assisted power steering with driving dynamics, it plays a substantial role. Steering feel and effort can be tuned for each Chevrolet model so equipped - whether it's an Impala, Malibu or Sonic - not to mention the weight savings and reduced parasitic losses on the engine compared to conventional hydraulic power steering.
Driving dynamics must serve multiple masters - safety, comfort, and performance - that are spot on for the vehicle and, like every Chevrolet product, a fun-to-drive factor extends across the model lineup. Want proof? Meet John Buttermore who, on weekends, races his Chevrolet Corvette in the Sports Car Club of America's Touring 1 class - in fact, he was the national champion for 2011. But during the week,
Buttermore works for Chevrolet as the lead development engineer for the Chevrolet Sonic. No one expects Sonic to perform like a racing Corvette, but Buttermore considers it his job to make sure Sonic's driving dynamics are the best he can make them. "Road racing has been a hobby for years, and our team expends a lot of effort tuning our Corvette to get the best performance," Buttermore said. "Working on Sonic is no different."
Magnetic Ride Control
Magnetic Ride Control - also pioneered in the Chevrolet lineup by Corvette engineers almost a decade ago and offered on every Corvette model now - is standard on Corvette 427 Convertible and ZR1, as well as Camaro ZL1, which was the first application of the "Gen 3" or third generation system. It includes driver-selectable Tour and Sport modes, plus Track mode on models with PTM, and uses advanced magnetorheological science that incorporates microscopic particles that react to magnetic inputs to produce shock damping with the highest level of precision, enabling body control optimized for everyday driving as well as on-track performance.
Also a potential trickle-down technology feature is ceramic brakes. Corvette ZR1 has massive horsepower, but it must have massive stopping power too. It does, thanks to its Brembo® carbon ceramic brake rotors that weigh almost 50 % less than equivalent cast-iron units. The system employs 6-piston front and 4-piston rear calipers engaging vented, cross-drilled rotors.
And as confirmation of the "Race on Sunday, be smarter on Monday" concept, Sonic will go racing, either late this season or early in 2013. The Sports Car Club of America, the Pirelli World Challenge, Grand-Am and several other motorsports sanctioning bodies have introduced a new class for road racing that utilizes smaller cars like the Chevrolet Sonic, as well as the Mini Cooper, Fiat 500, Honda Fit, Ford Fiesta and Mazda2 that allows only minor modifications, to keep the cars safe and affordable.
Mark Kent, director of racing at General Motors, is enthusiastic about the series, nicknamed "B-Spec" because, based on size, all the cars competing are within the global automotive "B" size category. "We think the Sonic is a great platform with which to compete in the B-Spec series. Because the B-Spec series should appeal to a younger, more tech-savvy racing demographic, we believe it's an opportunity to demonstrate Sonic's capabilities in front of an audience that we may not be reaching with some of our other racing series," Kent said.
The series is targeted at making road racing accessible and affordable, especially for those new to the sport. The kit is under development and will include performance and safety equipment, which will be marketed by an outside supplier selected by Chevrolet.
Consequently, choosing the best available tires and suspension components, and fine-tuning braking and steering feel are no less important on Sonic than on Chevrolet performance flagships like Corvette and Camaro.
"Our target for Sonic was to deliver a no-compromises car," Buttermore said. An example: "The base tire not only helps offer an EPA-estimated 40 miles per gallon on the highway with the available 1.4-liter turbocharged engine and 6-speed manual transmission, but it has the traction to deliver best-in-class stopping distance based on third-party testing. Finding dual competency out of one product is a way we approached this goal."
Chevrolet models like the gas-sipping Sonic, Buttermore said, "have a lot of selling points on fuel economy and safety. But at the end of the day, you spend a lot of time in your car. We want everyone to enjoy that time. And 'fun' is the best way to describe that feeling."
"What's rewarding about doing this is seeing all the triumphs, all the effort that goes into developing a vehicle and then seeing it all come together. We were very confident that these cars would perform well and they did. But what's more rewarding is seeing it in person. You come with high expectations and then you get to look at what the cars can do, and point and say, 'We did that.' There's nothing like it."