Don't Call The C8 Corvette "Mid-Engined" - The Explanation Behind The Corvette's New Engine Layout

Author: Paul Huizenga | 02/16/2021 < Back to Motor Life Home

First shown to the public on July 18th, 2019, the eighth-generation Chevrolet Corvette marked a radical departure in design from previous generations of production Corvettes, and fulfilled the decades-old promise of a GM performance flagship with the engine mounted behind the passenger compartment, in the manner of so many European exotics. Fans of America’s Sports Car had been teased over the model’s long history with concept vehicles like open-wheel Chevrolet Engineering Research Vehicle (CERV) of 1959, the full-bodied CERV-II introduced in 1964, and the CERV-III/Corvette Indy that was first shown at the Detroit Automobile Show in 1986, all of which placed the occupants ahead of the powerplant.

The 2020 model was hailed by many as the ‘first mid-engine’ Corvette, but like so many popular terms in the automotive world, that moniker was factually incorrect. In truth, every Corvette manufactured since the 1963 model year has been mid-engine, and acknowledging that fact is more than just pedantics. The position of a car’s heaviest single component relative to the wheelbase and to the driver plays an enormous role in vehicle dynamics, chassis tuning, and even interior space and aerodynamics. It’s so important, in fact, that simply calling the C8 “mid-engine” is about as useful in describing it as calling it a “two-seat” Corvette.

Words Mean Things

The argument in favor of calling the C8 “the first mid-engine Corvette” basically boils down to a single point; “Everybody knows what that means!” Unfortunately, much like the misuse of the word “literally” has literally redefined it to mean “figuratively” in common speech, we’re not using perfectly good descriptive terms with well-established engineering definitions, resorting to lazy shorthand instead. That’s a shame, because understanding what “mid-engine,” “front-engine,” and “rear-engine” actually mean from a design perspective can tell us a lot about the engineering tradeoffs and performance goals of a particular car design.

C3 Split View

This body-off image of the C3 shows how far back the engine sits relative to the front axle, but with the transmission directly coupled to it, a front weight bias was inevitable.

First, let’s define terms. In non-colloquial use, a “mid-engine” vehicle has the prime mover’s center of mass somewhere in-between the centerlines of the front and rear axles. This can be ahead of the passenger compartment (“front-mid-engine”), behind the passenger compartment (“rear-mid-engine”), or in some very, very rare cases like the first-generation Toyota Previa minivan, directly beneath the passenger compartment. Vehicles with engines placed outside the wheelbase are simply “front” or “rear” engine designs, but even mid-engine configurations also have the property of being either front- or rear-engine as well.

Why is this important? For performance-oriented vehicles, a mid-engine design is advantageous because it reduces the moment of inertia, which is the amount of torque required to rotate the entire vehicle around its ‘yaw’ axis. If you imagine the effort needed to twist a dangling kettlebell weight versus that which is necessary to spin a dumbbell of the same mass, you get the idea. By placing the most massive components within the wheelbase, a car takes less force to change direction, making it more responsive to steering wheel input and putting less of a load on the tires and suspension, all other factors being equal.

Another important aspect of vehicle dynamics is front-to-rear weight distribution. While this topic gets complicated when you throw in the effects of staggered tire and wheel sizes, in general terms, designers of cars with sporting pretensions try to keep the front and rear as equally loaded as possible. This has benefits in every aspect of acceleration, braking, and cornering performance, but is often hard to achieve when the practicalities of fitting an engine, transmission, humans, and useful storage space into a given design are taken into account.

Real-World Examples

To really understand what “mid-engine” is, it can be helpful to know what it’s definitely not. Two iconic ‘economy’ cars stand as the archetypes for designs that prioritize practicality and packaging far above sports-car handling: The air-cooled Volkswagen family, and the Austin Mini. Both push all the mechanical bits out to the very far ends of the car in the name of freeing up room between the axles for people and payload.

The Mini is the ancestor of pretty much every front-wheel-drive transportation appliance that followed, right up to today - a compact transverse-mounted inline engine ahead of and powering the front wheels, with a strong forward weight bias and the desirable trait (at least for cars driven by casuals) of understeering at the limit of handling. The original Mini was like an automotive TARDIS, with more room on the inside than on the outside thanks to having no mechanical components intruding on the passenger compartment. The fact that it found widespread success in competition is a tribute to its ubiquity, durability, and the willingness of racers to overcome any obstacle, rather than its suitability for the purpose.

While the aircooled VW never found the same level of road racing popularity as the Mini (Herbie the Love Bug movies notwithstanding), its lineal descendants include the Porsche 356 and the iconic 911. The latter is a masters-level course in making the most of a bad situation - while early 911s were quirky but not treacherous when driven at the limit, as more and more powerful versions were developed, even enormous tire-width offsets front to rear couldn’t tame the car’s reputation for being eager to swap ends in response to either too little or too much throttle mid-corner.

Over the years, Porsche managed to breed much of the snap-oversteer out of their performance flagship through subtle changes to chassis and suspension design as well as more aggressive alterations like all-wheel drive. But the fact remains that for the Boxster/Cayman and 918, an engine placed ahead of the rear axle rather than behind was the preferred starting point.

Corvette at the Crossroad

The original 1953 Corvette, while revolutionary for the time, was far from what we’d consider a sports car today. Initially offered with the 150-horsepower “high output” Blue Flame inline-six engine backed by a Powerglide two-speed automatic and a solid rear axle, the C1 eventually received the now-legendary Chevy small-block V8 and an optional 3-speed manual transmission, but these upgrades were really just stop-gaps.

C2 Corvette

The “Mid-Year” C2 marked a significant change for the Corvette, from ‘personal luxury’ to ‘sports car.’

The C2, today known as the “mid-year” Corvette, marked the shift from ‘personal luxury’ to ‘sports car.’ With an independent rear suspension and the engine moved rearward to place its center of mass behind the front axle, the 1963 Corvette was the real first mid-engine model in the genealogy. As the years went on and the generations of Corvette came and went, it retained the front-mid layout in the C3, and through the major re-think for the 1984 C4. Though that generation represented a return to true sports car values instead of the bloated and underpowered ‘secretary’s car’ (as it was described in the media at the time). Chevrolet started from a clean sheet of paper for what was to come in 1997.

The C5 marked a watershed - though certain Corvette hallmarks like composite body panels and transverse leaf spring independent front and rear suspension remained, there were huge changes in store. The 1997 Corvette introduced the world to the LS engine, which retained bore spacing but little else from the previous first- and second- generation Chevy small-block V8 engines, as well as taking the front-mid powertrain layout to the next level by separating the engine and transmission.

In the C5, a torque tube carrying a driveshaft that spins at engine speed connects the engine and transmission, with the latter mounted directly to the rear differential in what’s known as a “transaxle” layout. By moving the heavy gearbox from ahead of the passenger compartment to behind it, the C5 Corvette achieved a front to rear weight distribution of almost exactly 50/50. The basic design was so successful that when the C6 debuted in 2005, it was a near-clone of its predecessor under the skin, and even the 2014 C7, which shared only a handful of minor components with the C6, retained a near-identical mid-front chassis layout.

C5 Skeleton

The C5, C6, and C7 Corvettes all share a very similar front-mid layout, with a torque tube connecting the engine mounted ahead of the passenger compartment to a transaxle just behind the seats. As a result, they all have near-perfect front to rear weight balance.

A New Direction

For the C7’s replacement, General Motors looked at the sports car market, and took aim at enthusiasts beyond the typical Corvette buyers’ demographic. Rather than continuing to dominate a segment where there was dwindling competition (primarily Aston Martin and Jaguar, who continue to produce front-mid two seaters), Chevrolet took aim at European exotics costing hundreds of thousands of dollars more by switching to a mid-rear drivetrain layout that pushed the driver’s seat almost a foot and a half closer to the front axle, reduced interior storage space by two cubic feet (now split between a “frunk” in the nose and a storage compartment behind the engine and transaxle), and resulted in a 40/60 rear weight bias.

The C8 is the only Corvette besides the original model to be offered without a three-pedal option, as a Tremec 8-speed dual clutch gearbox is the only transmission available at the model’s launch. One seemingly minor ‘first’ that will help sales overseas is the fact that the mid-rear layout made offering right-hand-drive models relatively easy. While modern Corvettes have always punched above their weight in terms of performance and value for money, the 2020-up models are positioned to compete in a whole new market, but whether people will actually cross-shop the C8 against other mid-rear sports cars from more exclusive manufacturers remains to be seen.

Undoubtedly, the C8 is a dream fulfilled for many die-hard Corvette enthusiasts, even though in some ways it’s a step backwards in terms of practicality, and will require both Chevrolet and the aftermarket to re-learn many of the lessons that applied to the C5/C6/C7 generations due to the inherently different characteristics of even lower moment of inertia and a significant rear weight bias in the new Stingray. Call it what you want - the “ultimate Corvette,” a “bargain exotic,” or even “America’s Supercar” - just don’t call it “mid-engine,” because that does a grave injustice to all the amazing Corvettes that came before.

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