If you want to totally enrage Corvette fans, here's a fun thing to do: argue that the Corvette should be a four-cylinder. Then watch the capillaries burst in their cheeks as red-hot indignation flows like 93-octane through a Holley double-pumper. The notion of neutering the Corvette down to anything less than full V-8 glory is right up there with pawning the Constitution to China or outlawing hamburgers or declaring soccer the national sport. And yet, when you see a new seventh-generation Corvette lope past on the street, chances are it's powered by a four-cylinder -- 3.1 liters, 126 hp, and 221 lb-ft of torque. Oh, great. Texas just seceded.
Fear not, fellow Americans, for the 2014 Chevrolet Corvette Stingray's four-cylinder antics are strictly temporary, and the new 6.2-liter LT1 small-block can be instructed to keep all eight cylinders ready to spin out 460 hp at a prod of the throttle. But the fact that the Corvette even offers cylinder deactivation is a signifier of how thoroughly reengineered the C7 is compared with its predecessor. This is not a C6 with 25 more horsepower and LED strips draped along the headlights.
I get my crack at the C7 at GM's Milford Proving Ground, where the first order of business is for a security guard to carefully place GM-issued stickers over my iPhone's camera lenses. Then we head out to the Black Lake to drive a . . . C6? The yellow Z06 is stuffed with what looks like Mars Rover lab gear beneath the hatch -- data-gathering equipment for the new active electronic differential, dubbed eLSD. GM developed the eLSD in-house, and this Z06 mule can demonstrate the breadth of its capabilities with the flick of a switch. Essentially, an open diff lets the rear end rotate and point the car into a turn, as evidenced by the tank-slapper that ensues when the steering wheel is cranked 45 degrees at 60 mph. A locked diff helps put the power down but results in a car that wants to go straight, a point proved by the Z06's dogged understeer after the same 60-mph juke to the right. Thus, the challenge was programming the electronic diff to progressively manage those two goals in real time as the car circles a racetrack. If you're going to go through all this trouble, why not go all the way and have a torque-vectoring active diff?
"Well, torque vectoring adds weight and cost," says Heath Holbrook, the guy in charge of developing the eLSD. "And if you've already got a lightweight, well-balanced platform, then you get 90 percent of the benefit without the drawbacks."
"So torque-vectoring is kind of a Band-Aid?" I ask.
"You said it, not me!" Holbrook replies.
The C6, frankly, needed some sort of Band-Aid where its ten-tenths behavior was concerned. Although it was always a world-class speed demon, a C6 at its limits is one of the scariest rides that doesn't involve rodeo clowns. Maybe it has something to do with GM building its own private racetrack ten years ago, but more recent cars like the Cadillac CTS-V and the Chevrolet Camaro ZL1 feel much happier on a road course than the outgoing Corvette does, even if they're not as fast.
To see whether that situation has changed, I fire up a searing red C7 and head onto an autocross course set up on the yawning expanse of blacktop. Chris Barber, vehicle performance engineer, rides shotgun. First impression: this thing sounds like a Vette, with a deep, ragged rumble that smooths out as you release the clutch. Second impression: great seats. Much has been made of the fact that the C7 offers two seating options: all-around touring seats and track-biased competition chairs. I ask Barber if this is the competition seat, and he informs me that this is actually the relaxed-fit base model. Compared with the old car's flabby, lazy-river chaises, even these standard seats are like Le Mans prototype racing shells. "I think the standard seats would be fine for most people, even for track driving," Barber agrees
After a few acclimation laps, I run through the Vette's driver-assistance programs as I get more daring with the throttle. Like the ZL1, the C7 will progressively draw back the curtain on its capabilities according to your comfort level. Track mode is the last stop before "everything off," and the idea is to provide the kind of high-performance traction control that would be outlawed in most actual race cars: flatten the pedal on corner exit and the car will deploy as much power as the tires can handle, just like a Ferrari 458 Italia in race mode.
The Corvette's power management isn't as smooth as Ferrari's -- when your throttle foot overwhelms available traction, the big V-8 makes anguished stuttering noises that let you know it's struggling not to Hulk out and spin you into the bushes. But man, does it work. GM says that a pro driver will turn the fastest laps with everything off, but a driver who's merely really good will be fastest in track mode.
Out here, with nothing but cones to hit, I want to find out if the eLSD has tamed the Vette's appetite for destruction. So I deactivate stability control and go hot into the wide sweeping left at the beginning of the course. Tires howling, rear end crabbing, this would be the point where a C6 would reveal exactly where my skills run out. But the C7 hangs on and swings through the next slalom, the nose darting into the corners on lift throttle and the tail settling with a dose of power. Of course, I test the laws of physics and manage to spin a few times, but on the last set of corners, the rear tires leave a neat pair of stripes scribing an ess out onto the main straight. "I never could've done that with a C6," I say. Barber, gamely abiding these shenanigans from the passenger seat, translates my observation to engineering terms: "The C7 will tolerate more slip angle." Now let's go to the track.
The Milford Road Course is 2.9 miles of climbing, plunging, twisting pavement designed to make cars unhappy. If a lap here is fun, that's an accidental byproduct of the main goal, which is to exorcise chassis demons before production vehicles are sent out into the world. I don't think it's a coincidence that GM's cars have become ever-better road-course weapons since they built this place. "Here, you're pulling 0.9 g on the straightaway," says Corvette chief engineer Tadge Juechter. You know it's a tough track when the straightaway is a corner.
Weight is the enemy of lap times, and that's the one area where the C6 trumps the C7. Despite the C7's aluminum frame, carbon-fiber hood and roof, magnesium-framed seats, and center-tunnel insulation made from Aerogel -- one of the world's lightest solid materials -- the C7 is heavier than its predecessor. GM lists the base Stingray at 3298 pounds, 90 pounds more than last year's model.
In the most basic sense, the new car offers a lot more features than the old one, and additional capabilities generally presage additional weight. For instance, adding cylinder deactivation required a move to a steel torque tube instead of aluminum, because V-4 mode generates low-frequency resonances that only a steel torque tube can smother. "That added eight kilograms [17.6 pounds]," says Juechter. "From a performance perspective, that is trivial. So for the huge gain in fuel economy, you've got to do it." Juechter says that on the street in Eco mode, his best twenty-five-mile drive averaged 37.2 mpg.
That new interior adds weight, too, for the simple reason that padding and nice materials are going to weigh more than naked plastic. I talked with interior design manager Ryan Vaughan, who told me that weight was the single biggest concern. "In a normal program, you fight for every dollar," he said. "Here, everybody knew what we needed to do and there was no resistance to spending what it took. There was more discomfort when there was something that added weight, because they were very sensitive to that."
Whatever it weighs, the new interior is killer. The eight-inch high-res display in front of the driver is particularly entertaining, as it can morph into several different presentations (including my favorite, a Motec-style rpm bar graph). It's flanked by analog gauges, which help hedge the inevitable digital-display datedness that will set in when 2014's high-res looks like an Atari 2600 compared with the new hyper-realistic holoscreens in the 2024 models.
Speaking of the C7's future as a used car, buried in that display is a gauge that will prove useful for comparing secondhand Vettes: in addition to mileage, the C7 logs total engine revolutions. So you should be able to get an idea of whether a given car spent its life loping down the highway in seventh gear or clocking hot laps at the nearest track.
At Milford, GM coned off two areas that might prove deleterious to the health of the C7 and its drivers. A chicane breaks up a particularly brutal high-speed section, and the steeply banked carousel-style corner will not be scraping off any chin spoilers this afternoon. I strap on a helmet and climbbehind the wheel of a Stingray equipped with the $2800 Z51 performance package. There isn't much choice in the matter, as every car here has the Z51 Performance Package. Which makes sense, because you'd be silly to buy a Corvette without it.
Opting for Z51 gives you the all-important eLSD, as well as dry-sump lubrication, differential and transmission coolers, and aero upgrades. Performance-wise, you'll also want the magnetic ride control with performance traction management ($1795) and the dual-mode exhaust ($1195). If Chevy is looking for a slogan for that optional exhaust, I'd like to suggest, "It only adds five horsepower, but it sure does sound like more!"
The cars queued up at the track are all manuals, too. The automatic puts more weight on the rear tires, making it the nominal 0-to-60-mph champ, but out here the stick is what you want. Shift paddles flank the steering wheel with either transmission, but with the manual they control the transmission's electronic rev-matching function, with the prominent center-display gear indicator changing from white to yellow to indicate the system's activation. With that display showing a yellow "1", I go booming away from the pits and out onto the track.
Up to 4700 rpm, the LT1 makes almost as much torque as the old Z06's LS7. Running in track mode, there are corners where I could probably downshift to second, but third still pulls hard enough to invoke some electronic torque management if I unwind the wheel too fast. The C7 isn't as explosive as a C6 Z06, but the lazy low-rpm behavior of the LS3 is definitely banished.
I'll admit that I never turn off the entire electronic safety net on this particular gray-hair-promoting course, but track mode allows enough chassis leeway to reveal that this car is much, much friendlier than the C6. Most gratifying is that this Vette is predictable. Whatever you're trying to do, whether it's trail-braking into a hairpin or powering out of a 100-mph sweeper, somebody has already thought about that situation and tuned the differential lockup, throttle response, suspension stiffness, and about a million other parameters to make the car respond consistently. There's even a system that predicts the tire temperatures and adjusts the chassis controls to raise the thresholds of intervention as the tires warm up. You can turn off traction management and disable rev matching, but there are nonetheless always a lot of computers at work figuring out how to keep you hurtling toward the next apex.
Yet, you're really not aware of any of that when you're driving. Like many a Vette before it, the C7 coughs and bellows and invites you to pop off its targa top and lay down an endless pushrod V-8 burnout like the lout it's always been. Never mind that variable valve timing means that any rough-camshaft idle shake is premeditated. Never mind that the targa top is exotic-car-worthy carbon fiber. And never mind that the parallel stripes of rubber you'll paint on the pavement might be enabled by a hydraulic clutch pack running its own dedicated ECU programmed with in-house algorithms.
The trick with modern performance cars is adding these new layers of digital speed enhancements without ending up with a car that feels like a driving simulator. And that's the real achievement with the Corvette Stingray. In the course of optimizing this torrent of ones and zeros, Chevrolet still remembered to make the C7 loud, brash, low, wide, and menacing. It's smarter and sharper -- and sometimes it's a four-cylinder -- but it's still a Corvette.
Figuring it Out
A while back, a delivery-truck driver loading a Ferrari FF told me to push down on its front end with the ignition off. The car bounced freely. He said that Ferraris loaded tightly on trucks have been getting dented hoods because they bounce up and down so much. I hypothesized that the magnetorheological suspension must go AWOL with the ignition off, so without power they basically lose their dampers.
At Milford, I asked Tadge Juechter about this, and he said that’s exactly what’s happening. Actually he said something like, “Oh, I guess they haven’t figured that out.” He said GM wrestled with the same problem and used to solve it by shipping Corvettes with pucks inserted into the suspension to prevent them from moving much during shipping. Problem was, dealers would sometimes forget to remove the pucks. “One guy complained to me that his Corvette had an awful ride even though it had this high-tech suspension,” he said. “So I reached under it and sure enough, the pucks were still there. I pulled them out and it was like I’d magically fixed his car.” So GM decided that the puck system wasn’t working. Standing there next to a parked C7, I pressed down on the fender and the car barely moved. What was the solution? “We figured it out,” he said.
2014 Chevrolet Corvette Stingray
| Price: | $51,995/$69,775 (base/as tested) |
| Powertrain | |
| Engine: | 16-valve OHV |
| Displacement: | 6.2 liters (376 cu in) |
| Power: | 460 hp @ 6000 rpm |
| Torque: | 465 lb-ft @ 4600 rpm |
| Transmission: | 7-speed manual |
| Drive: | Rear-wheel |
| Chassis / Steering: | Electrically assisted |
| Front Suspension: | Control arms, transverse leaf spring |
| Rear Suspension: | Control arms, transverse leaf spring |
| Brakes: | Vented discs, ABS |
| Tires: | Michelin Pilot Super Sport ZP |
| Tire sizes F, R: | 245/35R-19 (89Y), 285/30R-20 (95Y) |
| Measurements | |
| L x W x H: | 177.0 x 73.9 x 48.6 in |
| Wheelbase: | 106.7 in |
| Track F/R: | 62.8/61.6 in |
| Weight: | 3402 lb |
| Weight dist. F/R: | 50/50% |
| 0-60 mph: | 4.1 sec |
| Top Speed: | 185 mph (est.) |
| EPA mileage: | 17/29 mpg (est.) |
No comments:
Post a Comment