Tuning the 2024 Corvette E-Ray for Exceptional Drivability
Corvette’s top engineer shares unique control, battery, and mechanical details of the new hybrid supercar’s propulsion system.
The challenge with any hybrid-electric vehicle is programming two propulsion sources to provide seamless response in every driving mode—acceleration, braking, cruising, etc. And that includes the first electrified Chevrolet Corvette.
During the 2024 Corvette E-Ray’s recent launch, executive chief engineer Tadge Juechter shared with SAE Media key insights his team realized during the new hybrid’s six-plus years of development.
There are three distinct E-Ray battery-charging strategies:
- Coast regen: With every lift off the throttle, there is light energy regeneration (the electric drive motor acting as a generator to charge the battery). This, according to Juechter, is not like one-pedal driving in a battery-electric vehicle but instead more akin to what results when a non-hybrid vehicle slows due to the engine’s compression braking.
- Brake-apply regen: When the brake pedal is first applied, progressive regen gives expected deceleration in the E-Ray. Like most hybrids and EVs, as the driver requests more decel, the friction brakes engage adding to the regen-provided decel. The C8’s Bosch I-Boost brake booster, which operates using electric power instead of engine vacuum, is instrumental in providing a seamless transition to any desired degree of braking.
- Through-the-road charging: Under certain conditions, the vehicle commands more engine output than the driver is requesting with the throttle pedal. The front-mounted electric motor is then switched to generator and regen mode to provide the driver a net intuitive feel.
Juechter added that a key E-Ray enabler is a relatively small battery, the cell chemistry of which is engineered to rapidly dispense and receive electrical energy. The Charge+ feature combines the high engine output during acceleration with aggressive regen to charge the battery from nearly depleted to fully charged in 2-3 miles (3.2 to 4.8 km) depending on speed. It’s difficult to deplete the battery’s state of charge in most driving situations, he asserted.
As an example, during quarter-mile acceleration tests when the electric motor is a major contributor to performance, returning to the staging area for the next run is sufficient to top off the battery’s charge for the next go.
The one circumstance where the battery is quickly fully drained is drifting. Here, the throttle is aggressively applied to break the rear tires loose while opposite-lock steering maintains a circular arc. Since such activity is largely confined to the test track; ordinary drivers see it only in demonstration videos.
Juechter added that a noteworthy change to the Corvette’s Tremec 8-speed dual-clutch transaxle was necessary for E-Ray. The engine-driven mechanical pump that provides the transmission’s hydraulic operating pressure is supplemented with an electric oil pump. This is necessary to enable declutching the rear wheels and gear staging with the engine shut down during EV driving mode.
Regarding the front-drive equipment, an electronically controlled clutch attached to the traction motor’s output shaft opens at 150 mph (241 km/h). An 8.16:1 reduction gear connects to an open differential which in turn drives the half-shafts. The coil spring-damper units are moved upward to provide room for the half shafts while preserving ride travel. A new cross-car brace maintains structural stiffness, Juechter noted.
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