The Corvette is finally the supercar it deserves to be
Chevrolet moved the engine behind the driver, where it belongs.
The Corvette was a hell-raising sports car that pioneered leading-edge performance technologies like fuel injection, independent rear suspension, rear disc brakes, unidirectional tires, magnetically adjustable shock absorbers (the same ones Ferrari uses now) and more. There was a reason astronauts drove Corvettes.
In recent decades, however, its reputation has tarnished. The Corvette is seen too often as an anachronism or a sad totem of mid-life crises. The ‘Vette wasn’t supposed to be a relic, trapped in ember in the 1970s and frozen in time to be idolized by drivers who are now in their golden years. We shouldn’t be in the place where the mighty Chevy Corvette—“America’s sports car” and bearer of the Stars and Stripes in international competition against the likes of Porsche and Ferrari in prestigious races like the 24 Hours of Le Mans—would come to be viewed so skeptically.
Yet here we are, with the Corvette commonly held in low regard by enthusiasts, no matter how many times Chevrolet’s bright yellow beasts defeat the Europeans at their own game at Le Mans. That’s eight class wins in 20 races for the current racing program.
It went wrong when Chevrolet failed to execute plans to switch the Corvette from a front-engine design to a mid-engine layout, despite numerous efforts to do just that. Either due to executive disinterest, failure of a planned rotary engine in the 1970s, or corporate bankruptcy in 2009, Chevrolet engineers’ plans to keep the Corvette modern stumbled time and again.
Until now. Finally, the mid-engine 2020 Corvette Stingray is a reality, and one drive demonstrates why the engine needs to sit behind the driver. It should have been there for decades, but it’s there now and it elevates the new ‘Vette to a new level.
Consider that the last front-engine car won in Formula 1 in 1960. The front-engine roadster passed into Indy 500 history after the 1968 race. Iconoclastic entrepreneur Don Panoz famously fielded front-engine LMP-1 sports racers at Le Mans between 1999 and 2002, using bellowing Ford V8 power to stun the Europeans, but alas, never defeat them for the overall victory.
The physics simply demand that the engine goes behind the driver. A car that accelerates forward transfers weight to its rear wheels, increasing the available traction from those tires to accelerate faster, even while cornering. There is no way to overcome this fact, and when the heaviest part of a car— its engine—sits over the front wheels rather than the rears, it is prone to spinning those rear tires under acceleration or sliding the rear tires and spinning while trying to accelerate out of corners.
Not coincidentally, those were the exact criticisms of the outgoing seventh-generation Corvette (C7), especially in its fastest, most powerful Z06 and ZR1 iterations.
Putting the engine at one end of the car and the transmission at the other, as the old Corvette did, also creates a high polar moment of inertia because the mass is concentrated at the ends of the vehicle rather than at its center. This makes it easier to spin the car, or at least, harder to catch once it starts to rotate about its center.
Now, with the C8 2020 mid-engine Corvette, Chevrolet has addressed those shortcomings. Bolting the engine, transaxle, and rear suspension directly together in one assembly that is securely fastened to the chassis produced a foundation that is 40 percent more resistant to twisting forces, reducing the undamped spring action of the frame and leaving that work to the suspension and tires, as designers intended.
That let vehicle dynamics engineer Mike Hurley finally do his job to the best of his ability, unshackled by the inherent shortcomings of the old configuration. At the same time, the tools at his disposal are better than ever, as the Corvette debuts the fourth generation of the Magnaride magnetically adjustable shock absorbers that co-debuted with the Corvette and Cadillac models.
The damper body itself is unchanged from the third generation, explained Hurley, but the electronic controller has improved and it now incorporates an accelerometer to directly measure vehicle motion rather than calculating it from the sensors measuring suspension travel. And Chevy has upgraded those sensors too, changing from simple mechanical position sensors to accelerometers mounted at each corner.
The old mechanical system suffered from a margin of error due to movement and vibration in the linkage that limited the ability to precisely understand the conditions during small movements, Hurley explained. Driving over a lightly textured surface like gravel could lose all of the information within the “noise” of that variability, so the suspension team couldn’t calibrate the system to smooth out the ride in those conditions, he said.
The accelerometers at the wheels and the one within the control unit provide more accurate information on the state of the car, therefore making it easier for engineers to address the situation with adjustments to the magnetic dampers.
The resulting refinement and serenity of the Corvette’s ride during our test drive outside Phoenix is a revelation compared to the old model. Making the frame stiffer means the springs can be softer, and the damping action can be more compliant.
With more weight on the rear of the car, the team, which had no experience with mid-engine designs, learned through trial and error that old remedies for familiar problems no longer worked, Hurley reported. Where an issue might previously have been addressed by firming the response at the front dampers, the new car might require softening the rear to solve the same problem, for example.
Cabin noise is noticeably diminished by the engine’s relocation. You’ve likely seen this before. Remember how noisy that front-engine school bus you used to ride was? But city buses, with their engines out back, are whisper-quiet by comparison, as all the noise goes back toward drivers in cars behind the bus.
In the new Corvette, that engine is a gem. It is the latest version of the famous small block Chevy V8, dating back to 1955, and at 495 horsepower and 470 lb.-ft., it is the most powerful base engine in the Corvette’s history.
This new LT2 engine is similar to the LT1 that powered the 2019 Stingray, with some tweaks related to its new location. The engine sits an inch lower in the car and bolts directly to the Tremec eight-speed, dual-clutch transaxle. Front engine Corvettes since the 1980s had a rigid torque tube connecting the front-mounted engine to the rear-mounted transaxle.
Mounting the engine lower is good for lowering the car’s center of gravity, but it requires some adaptation. The new dry sump oil pan shaves an inch of depth from the bottom (and more than a pound of weight), so it is not too close to the road surface. The pan features oil and coolant passages that increase cooling capacity by 25 percent compared to the LT1 in the C7.
Sitting that low, there’s no space beneath the engine now for the exhaust manifolds to dump the LT2’s spent gases. So new tuned-length tubular headers that replace the previous cast aluminum exhaust manifolds now tip upward and run the exhaust out over the top. This, of course, brings exhaust heat from the fire of combustion to areas that were previously shielded, and so the engineering team relocated the heat-sensitive ignition coil packs from atop the valve covers down to the sides of the engine block.
The space vacated atop the valve covers now serves as a billboard for a badge touting the pride of the workers at GM’s Tonawanda engine plant that builds the LT2 engine. Corvette engines wore such badging in the 1960s, and GM president Mark Reuss personally advocated for their return on the C8’s powerplant.
The LT2’s camshaft has 12 degrees more duration and a millimeter more lift on the exhaust lobes to help evacuate exhaust gas from the combustion chamber to the headers, and there is tiny 4-degree increase in intake duration too. As before, the electronic cam phaser permits 62 degrees of variability to adjust to load and throttle position.
The cam’s aggressive profile previously led to a somewhat uneven idle, which didn’t project an impression of refinement and quality, which is another reason Europhiles were dismissive of America’s sports car. Advancements to the engine management system and the increased precision of a Wide-Range Air-Fuel sensor have made it possible to smooth that idle even with the still more aggressive cam profile in the LT2, and the improvement is unmistakable when the C8 is idling at traffic lights.
On the intake side there are improvements made possible by the extra space available. When the engine was in front, the Corvette’s swoopy, low hoodline forced the top of the engine to be as flat as possible. Now that the engine sits an inch lower and is behind the occupants, there’s plenty of space above.
Chevy used that space to enlarge the intake air plenum from 11.1 liters of volume to 14.1 liters. That provides room for all eight intake runners to measure 210 mm in length. Previously two of the cylinders had shorter intake runners than the other six to make space for the fuel pump. It would have been hard to have identical combustion in all eight cylinders with different-length intake runners, so this change should also contribute to smoothing the idle.
Moving the engine forced changes to the external oil tank used by the dry sump oil system to contain the oil that normally sloshes around in the bottom of wet sump oil pans. This new plastic tank mounts directly to the front of the engine, which is an area whose temperatures aren’t friendly to normal plastic materials. The Corvette’s oil tank is made of heat-tolerant composite resin, from two-pieces that are hot-gas welded together and containing an integrated oil centrifuge and separator system.
Improved efficiency in the tank’s design to separate oil from the frothy foam and in the scavenging system that recovers oil from the dry sump pan let engineers reduce the total oil system capacity by 2.25 quarts compared to the system in the C7 Corvette, while providing a reliable supply of lubricant during sustained 1.25-g cornering.
Transmissions used to be another Corvette component that technophile derided as out of date. The traditional H-pattern shifted manual transmission with a clutch pedal is a favorite of traditionalist do-it-yourselfers, but declared obsolete by others.
The C7 Corvette’s automatic transmission was a classic planetary automatic with a torque converter. These are great transmissions, and the Corvette’s was superb when left to its own devices so the computer controlled the shifting. But for manual shifts triggered by the steering wheel-mounted shift paddles, the automatic’s responses could be slow and clumsy, frustrating drivers attempting to emulate their Formula 1 heroes by clicking those paddles themselves.
The C8 Corvette Stingray has just one transmission, a fashionable eight-speed dual-clutch automated manual transmission. Such gearboxes are effectively a pair of manual transmissions with dual computer-controlled clutches that switch instantly and imperceptibly between the gear selected in one of these transmissions to a different gear in the other one.
While this Tremec TR-9080 arrives simultaneously with the seven-speed Tremec TR-9070 in the Ford Mustang Shelby GT500 as Tremec’s first dual-clutch transmissions, Chevrolet says that the two gearboxes surprisingly share very few parts.
Tremec says the TR-9080 DCT can change gears in less than 100 milliseconds without interrupting torque. “The lightning fast shift time is made possible by the integrated design approach with advanced Tremec-developed software algorithms, our transmission controller, proprietary clutch friction material, and world-famous hydraulic controls” said Antonio Herrera, managing director of Tremec.
In street driving, with a test of the Corvette’s launch control system, we found the DCT delivers on its promises. Early testers complained of some shift irregularities at the track, but it isn’t clear whether that was because of the different requirements of track driving or because their tests took place months ago and the problems they identified in their pre-production prototypes have since been fixed as the ‘Vette progresses toward its spring 2020 delivery to customers.
While the GT500’s launch control system lets drivers select from a range of engine speeds at launch, the Corvette’s launches are fixed at 3,500 rpm. The supercharged GT500 has significantly more torque to manage, making launches trickier. But also, the Corvette’s relocated engine sits over the drive wheels, ensuring better traction for acceleration, which means there is less variation from one run to another, so a fixed launch rpm is appropriate, reports Hurley.
Chevy’s stopwatch records a 2.9-second 0-60 mph acceleration time for the Stingray, but it fails to capture the laughs that the ridiculously easy and quick launches elicit from the driver. The Corvette is also programmed with the all-important dual-paddle pull feature that instantly shifts the car into Neutral, permitting a gratuitous rev of the engine in response to the waves and thumbs-up from other drivers seeing the C8 for the first time.
The car’s three driving modes, Touring, Sport and Track render decidedly different characteristics, even in street driving. As expected, Tour produces a comfortable ride from the Magnaride shocks and sedate behavior from the engine and transmission, making the Corvette a comfortable highway cruiser.
In sport mode, ride motions are tighter and the transmission becomes more involved. I noticed a subtle downshift when I lifted off the gas cresting a rise, which had the effect of using a little engine braking to help stick the front of the car to the ground over the crest.
Track mode yields the firm ride and frenetic transmission operation expected on the track that is not especially suitable for most street driving. We look forward to trying it on the track in final production form.
In the meantime, we’re left with plenty to appreciate from the Corvette’s move from nostalgia machine to contemporary super sports car. It may have been overdue, but it is no less impressive an achievement. It is time for the snobs to update their view of the Corvette and give this excellent sports car its due.