We could forever debate the philosophical implications of the Chevrolet Corvette’s switch to a mid-engine layout, but when it comes to physics, the repercussions are clear: moving the Corvette’s heaviest component behind the driver has a dramatic effect on the car’s ability to accelerate.
The Z51-package C8 and the outgoing Z51 C7 have similar weight-to-power ratios, yet the new car can sprint to 60 mph almost a second sooner. To understand why, you have to remember that a tire’s grip is related to the mass it carries. To maximize a powerful car’s ability to accelerate, you want weight over the driven wheels—but only enough so that the car can put its power to ground. Once you’ve accelerated and upshifted to a speed where traction isn’t a concern, weight is acceleration’s enemy. The trick to making a powerful car quick, then, isn’t to make it heavy. It’s to manage where the weight lies.
The front-engine, rear-drive C7 had a front-to-rear weight distribution of 49/51 percent—roughly 1750 pounds on its rear tires when the car wasn’t moving. The mid-engine, rear-drive C8 carries less of its mass on the nose—there are 2210 pounds on the rear tires when stationary. That’s 460 pounds more, which means considerably more available traction at the rear wheels.
Because weight shifts rearward under acceleration, that figure only improves as the car gains speed. To take advantage of this additional traction, Corvette engineers fulfilled their God-given purpose: they sent more torque to the rear wheels. Compared with the automatic-transmission C7, the C8’s first gear is a massive 21 percent shorter—the new car’s rear wheels experience a torque increase of more than 20 percent from that change alone. When you factor in the 10 lb-ft bump from the new V-8, the LT2, the C8’s rear wheels receive an additional 1350 lb-ft. No wonder the new Corvette wears 305-section rear rubber in place of the C7’s 285s.
Those gearing changes alone would account for almost half of the C8’s amazing 0-to-60 gap over the old car—a 1.0-second advantage. The rest, of course, is a function of the available traction at the rear tires, the LT2’s 35 additional horsepower, and finally, the dual-clutch transmission. Which can both shift without interrupting power delivery and perform a perfectly violent launch-control clutch dump.
And violent it is. The C8’s peak acceleration is just over 1.0 g, occurring almost a second after launch. That figure dwarfs the C7’s 0.7-g peak. And in case you’re wondering, at those respective peaks, the C8’s rear tires are under 2900 pounds of load, and the C7’s carry only 2150. The same dynamic weight distribution affects braking. Additional weight on the rear of a C7 would even out braking performance—under 1.0 g of deceleration, the car’s front wheels carry 66 percent of the car’s total mass, while the C8’s deal with just 57 percent. This means the braking components up front can be made smaller, and indeed they were. Front rotors shrank from 13.6 to 13.3 inches, and the rears grew, from 13.3 inches to 13.8.
Braking distances didn’t really change relative to the C7, but the C8’s switch to a brake-by-wire setup (there is no direct, physical connection between brake pedal and hydraulic system) carries a number of advantages. GM says the change allows for the deletion of the traditional brake booster and vacuum pump, moves that give more front-trunk space and better sightlines.
Those are certainly benefits, but they’re unlikely to be the real reason for the switch. Consider the by-wire system a tacit admission of a forthcoming hybrid Corvette. (Hybrids and most electric vehicles use blended brake systems that can continually shift braking duties between electric regenerative braking and the conventional friction brakes. The drawback is inconsistent and unusual pedal feel. A by-wire pedal eliminates this.)
Once we start thinking about a hybrid Corvette, the mid-engine layout really starts to pay dividends. Namely, the possible installation of electric motors on the front wheels, to provide all-wheel drive. Another traction path that would not have been possible with a front-mounted engine.
Finally, the mid-engine car’s added rear traction will be a huge benefit to the inevitable high-output internal-combustion variants. Like our C8 test car, the base C7 easily put its power to the ground. Only the supercharged Z06 and ZR1 models had trouble—and the next ones will have less. Add in electric all-wheel drive with torque vectoring across the front axle and it’s clear why the Corvette switched to a mid- engine layout.
Hang tight, my little puppy dogs, because this is going to be one hell of a thrill ride.
MISSING THE MANUAL
There’s only one reason to celebrate the death of the manual transmission in the Corvette: the C7’s seven-speed was geared so long that it sapped the punch out of holeshots. Able to achieve more than 50 mph in first (56 mph on C7s without the Z51 package), the front-engine car’s off-the-line acceleration wasn’t nearly as brisk as its mid-engine successor’s. First gear in the C8’s twin-clutch automatic multiplies torque by an extra 50 percent compared with the old manual—in fact, second is almost as long as the manual’s first. Gearing a manual C8 with ratios similar to those of the dual-clutch would slow the 0–60 sprint by the time it takes to make the two shifts between a standstill and 60. The delta would likely be about half a second.
I don’t know about you, but I’d be fine with a manual-transmission C8 capable of 3.2 to 60. On second thought, there’s no reason to celebrate the death of the Corvette’s manual transmission. Now get off my lawn.
