Design Notes: 4th Generation Corvette
Back to the future
The Aerovette, with its shockingly advanced shape, became the inspiration for the proposed mid-engined C4, not only in mechanical configuration but also form, after all few could argue it didn’t look like a Corvette.
This is a full-sized clay model from December of 1976 that, at first glance, looks just like the Aerovette. But, upon comparison, you’ll see several changes.
That’s because this clay model was the “productionized” version of the Aerovette that accounts for things necessary if it were to be built.
At this time, the mid-engine program was getting the majority of the attention. So much so that a mid-engined mule (built on a Porsche 914 platform!) had been constructed for testing. That’s where the mid-engine program lost its steam. Why?
Two problems were exposed by the mule. First was handling and Chevy recognized that Corvette customers had specific expectations about how their car should feel. The engineers ceded they didn’t feel they could meet those expectations with the new configuration in time for the debut.
The second problem had to do with power. In what seems a colossal oversight, the mid-engine proposal was planned from the start to be powered by the same engine/transmission combo as the upcoming X-cars (Citation/Phoenix/Skylark/Omega). That meant a 2.8-liter V6 pumping out a wheezing 110 HP. Boosting the engine’s output with a turbocharger was naturally considered but excessive costs (due to the unique design) and added component stress (which raised serious durability questions) were mortal blows to the doomed plan.
Full speed ahead
Even though the design work on a mid-engined Corvette continued, it was moved to the concept studio. Engineering for that proposal halted and the majority of the team’s attention was now focused on the front-engine project. After a relatively short period of time, things were taking on a shape we’d consider quite familiar.
Here is the concept sketch for the front-engine design program dated October 1978
To the right is an early clamshell hood sketch. The idea was said to have been introduced into the C4’s design as early as November 1978.
The head of Chevy 3 design group, Mr. Jerry Palmer, had set five requirements for the epic model being redesigned under his watch: more passenger room, increase cargo space, reduce the drag coefficient, reduce the car’s height, and modernize the firewall-to-axle proportion. Some of those requirements would seem to conflict with another.
For example, in considering reducing the car’s overall height, they determined the ride height (the space between the body and the ground) couldn’t be reduced much compared the outgoing model.
To resolve the dilemma, Mr. Palmer and his team devised an interesting approach. By relocating the lowest components in the old design, the exhaust, including the catalytic converter, out from under the occupants’ seats and into a center tunnel, designers could lower the roof–and occupants–without affecting the car’s ride height.
This is the reason the C4 has what some consider to be an awkward ingress/egress design; others, myself included, feel it adds to the exotic appeal.
Further mechanical advances under the hood, including the absence of a carburetor and a steering rack located in front of the motoe, allowed for a lower engine placement and sleeker hood line.