Corvette chief engineer Tadge Juechter recently acknowledged, "A mid-engine layout is something we consider for every new generation." What he didn't say is that, after six months of intense engineering effort, the mid-engine Chevrolet Corvette is dead. Again.
But not totally. In 2010, General Motors will strive for outright victory at the 24 Hours of Le Mans. GM's racer will be a Corvette conforming with the LMP1 (Le Mans Prototype) Evo rules that will govern the seventy-eighth running of the world's toughest and most prestigious endurance race (see sidebar). This Corvette will be powered by a V-8 engine positioned behind the driver, just ahead of the rear wheels. Selling on Monday what you race on Sunday is the cardinal rule that prompted Juechter's 2007 investigation of a mid-engine production Corvette.
Half a century ago, Corvette patron saint Zora Arkus-Duntov became obsessed with the idea after his experimental SS racer nearly cooked John Fitch at Sebring. Arkus-Duntov explained, "The Corvette SS we raced had a front engine and a magnesium body. If a suspension bushing had not failed, sidelining our effort, the heat from the engine and exhaust would have fried the driver. It was then that I switched my mental gears to mid-engine to get rid of this huge heat generator at the front of the Corvette."
Arkus-Duntov spent the next seventeen years investigating mid-engine cars for racing, for production, and to entertain his insatiable need for speed. Four successive Corvette chief engineers have borne the same cross.
Why all of GM's horses, men, and women can't drag a mid-engine Corvette into production is a sob story for another day. As solace, we offer this early look at the front-engine Corvette you will be able to buy in 2012.
Take our graphic depictions with a few grains of salt. No refunds will be issued in the likely event that these artistic expressions penned by the senior design class at Detroit's College for Creative Studies do not pan out. A dead accurate look at the next Corvette is impossible, because GM designers are still sculpting their curly cues and character traits. We can only hope that these student illustrations inspire the GM pros to greater heights.
Our preview of the C7's mechanical makeup rests on firmer footing. To gather these insights, we conspired with Peter DeLorenzo, founder and publisher of the Autoextremist.com Web site. This influential Detroit-based thorn in the auto industry's side has the tightest net of loose-lipped inside sources money won't buy.
Last December, President Bush signed a corporate average fuel economy (CAFE) standard into law that will eventually require every maker's car fleet to average 35 mpg or more. This doesn't mean we'll soon be driving 35-mpg Corvettes. Nonetheless, it's a long, steep road to 2020, and the next Corvette will have to exceed the 18-19 (combined) mpg offered by C6 models. Heightened efficiency will be achieved by the usual means: less weight, smaller engines, and reduced friction and aerodynamic drag. A hybrid powertrain is a possibility, but probably not before C8 arrives.
Juechter's boss, vehicle line executive Tom Wallace, who's responsible for all of GM's performance cars, has begun hinting that the C7 will be hundreds of pounds lighter. Shedding 200 pounds from a Z06 or 300 pounds from the standard Corvette coupe will move them below the 3000-pound barrier. (Think Porsche Boxster/Cayman.) Some of the weight savings will come from modest length, width, and wheelbase snipping. Use of ultralight materials, a longstanding Corvette pursuit, will trim more mass.
Consider a few examples: Substituting titanium for stainless steel in the 2001 Z06's exhaust system saved nineteen pounds. The shift from steel to aluminum for the 2006 Z06's hydroformed spaceframe dropped 137 pounds. Molding the ZR1's hood, front fenders, and roof skin in carbon fiber trimmed more than thirty pounds. According to Juechter, carbon-fiber doors and rear fenders would save another twenty pounds. The ZR1's carbon-ceramic brake rotors cut rotating, unsprung, and curb weight while also benefiting fade resistance. Significantly narrower tires and wheels also would subtract worthwhile heft.
GM Powertrain engineers have investigated cast magnesium transmission cases - a material already used for the Corvette's front subframe and roof reinforcement - because it's relatively affordable and one-third lighter than aluminum. Cast magnesium wheels were a Corvette option for seven years until comparable weight savings were realized with spun-cast aluminum. While a magnesium cylinder block is an ambitious leap, BMW has converted portions of its 3.0-liter six to this material. It only costs money, and in this business, the more you spend, the more you save.
The beauty of reduced curb weight is that it benefits both mileage and every facet of performance. But don't count on any acceleration gains, because the next Corvette surely will be powered by smaller (4.5- to 5.7-liter) engines. Luckily, the rest of the underhood news is good. There's no chance that the cylinder count will deviate from the current eight-pack, because keepers of the Corvette flame insist that a V-8 is vital and not eligible for sacrifice to the gas-mileage gods.
Three technologies available to uplift the Corvette's venerable pushrod V-8 are variable valve timing (VVT), direct injection (DI), and active fuel management (AFM). Taking those items in order, the Mechadyne/Mahle cam-in-cam VVT arrangement used successfully in the Dodge Viper's V-10 has been spotted being tested in GM V-8s. DI and AFM (GM's code for cylinder shutdown) have been seen fraternizing in the 4.9-liter, 326-hp V-8 that powers the GMC Denali XT hybrid concept vehicle.
We've heard wild rumors of one exotic engine planned for the Corvette. A spin-off of the UV8 - scheduled to replace what was formerly known as Cadillac's Northstar V-8 - would have used four camshafts and 32 valves to feed an ultrasmall displacement. A stratospheric redline and an exhaust shriek capable of rousing the lifeless would have been key character traits. Alas, the entire UV8 program was shelved last December as GM's salute to future mileage obligations.
The third engine penciled onto the C7's bill of materials is equally interesting. Plans are afoot to consider the General's new 4.5-liter Duramax turbo-diesel V-8 for possible use in a special, high-mileage edition of the 2012 Corvette. This engine definitely has the guts for the job: more than 300 hp and 520 lb-ft of torque. It fits the same hole as the current gasoline small-block V-8 and is remarkably smooth and quiet for a diesel. The highest hurdle is weight; while GM has not disclosed how much the Duramax weighs, its robust internal parts and cast-iron block are contrary to the Corvette's quest for anorexia.
To help any engine that makes the cut shine, there's a new dual-clutch automatic transmission under development for the C7. We don't know whether this gearbox will be located ahead of the rear axle (as in today's 105.7-inch-wheelbase Corvettes) or behind it, which would enable the wheelbase to be shortened to save weight and, theoretically, quicken steering response. The cost of a world-class transaxle to replace the Tremec six-speed was a key showstopper for the mid-engine C7.
Chassis details also are unknown, although there's little incentive to deviate far from the aluminum linkages and composite springs optimized during the past four Corvette generations. Transverse fiberglass springs date all the way back to 1981, when a weight savings of more than thirty pounds was realized. One flaw worth fixing is the front spring's location under the engine, an arrangement that elevates the entire driveline. Magnetically adjustable dampers surely will play a major role in the C7.
In summary, we're expecting a 3000-pound Corvette powered by a 300-plus-hp engine delivering at least 30 highway miles per gallon. There will be less raw-speed bang for more bucks. That poses two appropriate courses of action for Corvette enthusiasts: Start saving now for the most technologically advanced car ever fielded by GM. Or place your deposit on a ZR1 before they run out.
The Assignment:Draw the next CorvetteSince no spy pictures of the C7 Corvette exist, we decided to give America's next generation of car designers a chance to weigh in on what they think it should look like. We approached Mark West, a professor at Detroit's College for Creative Studies, who invited his students to participate. Shown here are five of the students' best sketches, evaluated by design editor Robert Cumberford.
[ Nic Stone ] Handsomely drawn, dramatic, and very nice. This is excessively conservative but very, very good.
[ Mykola Kindratyshyn ] The imaginative headlamps and the well-balanced composition are worthy of more development.
[ Mahdi Chowdhury ] Some nice ideas, like the floating lamps under the nose, the racing-car-fuselage power bulge, and the fighter-plane canopy - which would be tough, but not impossible, to realize.
[ Josiah LaColla ] An exciting lower body with nicely crossed hard edges defining ducted radiator outlets and brake scoops. A mid-engine Vette would be nice, but this design could fit the classic format, too.
[ Timothy O'Donnell ] The triangular headlamp covers are interesting and would be highly distinctive on the road.
Mid-engine 200-mph C7R Zora Arkus-Duntov's dream machine.
Le Mans rule makers are expected to scramble the deck for 2010, resulting in a new top category tentatively called LMP1 Evo. In essence, this is the merger of today's LMP1 and GT1 classes, with two goals in mind. The first goal is to reduce speeds to less than the 145-mph lap average exceeded in last year's twenty-four-hour race. The second is to shift appearances from fendered formula cars to racy road cars.
Evo racers will be coupes with wide windshields and side pontoons six inches higher than those fitted to today's LMP1 cars. Minimum cabin width and height are increased by 3.9 inches and 2.4 inches, respectively. Taking advantage of the rules change, Chevy will race a mid-engine Corvette at Le Mans in two years, finally fulfilling Zora Arkus-Duntov's fondest aspiration.