Yahoo Autos Turbo parts for an LT7 engine show up in GM's parts catalog
We don't remember a vehicle whose development was leaked and tracked almost exclusively by that vehicle's engine, other than the Chevrolet Corvette. First came decades of predictions as to when GM's small block would move, like Malcolm, to the middle. Then came years of chatter about the Z06 engine: In 2019, Bozi Tatarevic outed the 5.5-liter DOHC V8 designed for the C8.R race car as the 2023 Z06's powerplant. The same year, the same Tatarevic parsed internal GM docs that hinted at two hybrid Corvettes, "both a hybrid ZR1 and a hybrid base model." The hybrid is now suspected to be the Zora, above the ZR1, the E-Ray isn't exactly a base model, but you get the point. Two years before that, way back in 2017, a CAD drawing leaked that was reported to be the twin-turbo 5.5-liter LT7 V8 going into the ZR1. And now? Mid-engined Corvette Forum credits "little birdies" for screenshots of the latest GM parts catalog selling turbo components for a turbocharged 5.5-liter LT7 V8.
Among the trove were listings for a baffle bolt duct resonator retainer, an air inlet adapter, and ducting to the turbo inlet. A dialog box on an initial screenshot gave a partial description of the motor as, "LT7 - Engine Gas, 8 CYL, 5.5L, DI, VVT, AFM, SC Turbo, DOHC," before being cut off. The direct injection, variable valve timing, turbocharging, and double overhead cams line up with what we'd expect from a boosted Z06 engine. The "SC" in the turbo description is for supercharging, but a member of the Corvette Forum explained "for whatever reason, in the Parts Catalog and ECM Calibrations GM doesn't distinguish between 'Forced Induction' Turbocharger or Super Charger....they refer simply to SC/Turbo."
The "birdie" at the center of this later clarified that AFM, which is GM's Active Fuel Management cylinder deactivation, was a mistake. The Z06 doesn't use AFM, and lively debates on forums question whether GM would endure the expense and complexity of engineering an AFM solution. The Z06's LT6 uses mechanical lifters, and flat-plane-crank (FPC) engines have vibrational issues that would be exacerbated by shutting down cylinders and the ZR1's buyers won't fret over fuel economy.
