Corvette C8.R: Racecar first, road car second

The revelation of the Corvette C8 as a mid-engined platform upset the apple-cart for many of the brand’s hardcore enthusiasts. Corvettes – tradition states – are front-engine and rear wheel driven. That’s the American Muscle car way, apparently.

One must be mindful that ever since the C5.R took to the roads of Le Mans way back in 1999 as a GT racecar – Corvette had begun a transition as sportscar brand. Over the last 20 years; many of its Pratt and Miller-built cars raced against similar front-engined, rear driven cars with large displacement engines: The Viper GTS-R, Ferrari 550/575 GT1 and Aston Martin DB9 come to mind. All was right with the world.

Also thrown into that mix was Saleen’s S7-R. A rear driven beauty of an American Muscle car that had its engine behind the driver. Long before that, the original Ford GT40 – the most iconic of American Muscle cars also had mid-rear configuration.

But both those cars were built for one defining purpose: Racing.

The Saleen for example, was built around a honey-comb aluminium tub designed by Ray Mallock Limited, a British race engineering firm. The GT40 was even more extreme – originally built as a prototype racer with no intention of ever being on the public road.

So, after building its modern brand and identity around competing at Le Mans, Daytona, Sebring and Road America for more than 20 years – Corvette made the natural transition to becoming a race car first, and road car second.

You could argue strongly that Ford forced GM’s Corvette down this road. Vette’s famous American rival’s decision to build the latest Ford GT as a thinly veiled high-technology race car that practically played the ACO rulebook to perfection – a win-at-all-costs to celebrate 50 years since the GT40 won Le Mans – really escalated the GTE/GTLM arms race.

And while Balance of Performance (BoP) tried to even the field out, the Fords often had a dynamic advantage. The GT’s aerodynamics were previously unseen of in GTE/GTLM – the car appeared shrink-wrapped around its critical components with barely an element of excess to speak of. The car was designed and built by race car specialists Multimatic, contracted by Ford. The game had moved forward.

This was highlighted when Porsche – a longtime stalwart of racing its road-technology in its true configuration – changed its 991 RSR racer to a mid-engine configuration to remain competitive. Further evidence was BMW who chose to return to top-flight GT racing with the M8 GTE in the traditional front-rear configuration. While the platform had some success in IMSA; BMW withdrew from international competition after just one season.

With a long line of Corvette road cars being front engine, and with a loyal fan and customer base that identified with that element of the Corvette identity; why would GM eschew this and depart to a mid-rear platform? Well, to compete against the Ford GTs and Ferrari 488s of the world.

There are many performance advantages to gain from the mid-rear configuration. One of the more notable ones is the weight distribution. By pinning the engine behind the driver, the bulk of the car’s mass sits rearward and (typically) puts more downward force on the rear wheels – which equates to more grip and traction in a dynamic sense. This essentially is what a race car’s aerodynamics does as well, so having actual mass added increases the total force available.

Ideally, a GT race car has 50/50 weight balance over the front and rear wheels. In a front-engine, rear drive configuration – even with a drastic shift in the engine location lower down and hard against the firewall – 50/50 distribution is very difficult to achieve, with weight bias often being slightly forward. This adds extra loading to the front tyres – which (obviously) are used to steer the car. As there are few options a team can do in a homologated GT car to shift aerodynamic grip levels (many items such as the front splitter and dive planes are fixed) save for ride height adjustments and blanking of ducts to affect airflow speeds, finding ways to reduce load and conserve front tyres over a stint can become difficult to achieve.

For the Corvette C8.R, the front aerodynamics feature a less prominent front splitter than the C7.R. It also has a raised tunnel in the middle of the splitter ‘lip’ – much like the Ferrari 488 GTE and Lamborghini Huracán GT3 – to help push and focus more air under the flat front to increase vacuum and downforce. The lack of mechanical running equipment under the front hood of the C8.R (except for cooling coils) leaves more space for underfloor aerodynamic trickery to increase front grip levels.

There are two pairs of small dive planes rounding off the front of the C8.R, above the endurance light clusters. The radiator tunnels do no vent out through significant bonnet ducts, as seen on other GT racers (Porsche 991 RSR, for example).

The enlarged front race wheels sit in widened wheel arches, which feature cut-aways and ducting on the rear sides to allow for turbulent air to pass out to the flanks of the car at speed.

The top side of the car around the driver cabin is fairly plain, with no notable furnishings. According to Pratt and Miller, 80-percent of the C8 road car chassis makes it into the GTLM car – a much higher amount than previously.

Towards the rear; large, triangular ducts behind the cabin doors draw in air to the engine bay where the all-new naturally aspirated 5.5-litre V8 with a flat-plane crank lives, snuggled in with an XTrac 6-speed sequential gearbox.

It is interesting to note that for most GT race cars; front-engine configuration doesn’t necessarily lead to more space for rear diffusers, as most run a transaxle gear box that limits the start of the exhaust tunnels along the flat floor. As a mid-rear car also has the gearbox above the rear axle, diffusers can (for the most part) be the same size. The C8.R sports a large rear diffuser between the rear tires, which supplements a large rear wing that hangs off the back of the car and is connected from the underside of the wing chord via an ‘S’ bend mounting arrangement.

At the rear of the car, a single intake at the bottom of the roof line (under the wing) picks up airflow to likely feed a cooling device such as a transaxle cooler or even the driver Air Conditioning.

Hot air from the engine bay is expelled via two large rearward facing ducts above the rear wheels, as well as a void above the diffuser.

On the surface, Pratt and Miller appear to have not deviated too substantially from the C8 road car form to create the new GTLM contender, which helps justify the intention of moving to a mid-engine configuration in the first place.

And while the C8.R is yet to turn a wheel in anger, it has a big 2020 planned. Without doubt race fans can expect to see the car evolve over the year through Pratt and Millers expertise.

Photos by Christian Rodriguez.