Chevrolet Gemini small-block engine

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Gemini small-block engine
2023 Chevrolet LT6 engine, NYIAS 2022.jpg
Overview
Manufacturer General Motors (Chevrolet)
Production2022–present
Layout
Configuration 90° V8
Displacement 5,463 cc (333.4 cu in)
Cylinder bore 104.25 mm (4.104 in)
Piston stroke 80 mm (3.1 in)
Cylinder block materialSand-cast A319 Aluminum
Cylinder head material Aluminum
Valvetrain DOHC 4 valves
Compression ratio
  • 12.5:1 (LT6)
  • 9.8:1 (LT7)
RPM range
Max. engine speed 8,600 RPM (soft), 9,000 RPM (hard)
Combustion
Turbocharger Twin-turbo (LT7)
Fuel system
Management GM E68 (32-bit)
Fuel type Gasoline
Oil system Dry sump
Cooling system Water-cooled

The Chevrolet Gemini small-block engine is a dual-overhead cam (DOHC) V8 engine designed by General Motors. While technically a small-block engine because of its bore spacing of 4.4 inches, [1] [2] General Motors engineers do not consider it to be a part of the traditional Chevrolet small block lineage because of the substantial reworking, specialized development, and unique technical features distinguishing its design. [3] [4] [5]

Contents

The LT6 is a clean-sheet design, mechanically unrelated to both the LS-based engines and the Cadillac Blackwing V8. Its most notable traits include a flat-plane crankshaft and dual-overhead camshafts, which represents a departure from the traditional pushrod valves and crossplane crankshafts found in all previous generations of Chevrolet small-block engines. As of May 2024, the Gemini engine has only one variant, dubbed LT6. Hagerty , an American insurance company, reported in 2020 that a higher horsepower variant, the LT7, is expected to arrive in the 2024 model year. [6]

LT6

The LT6 is a 5.5-liter, naturally-aspirated V8 engine. It debuted in the eighth-generation Corvette Z06, and was unveiled on October 26, 2021. [1]

While the LT6 features a redline of 8,600 RPM, it generates a maximum of 670 hp (500 kW; 679 PS) at 8,400 RPM and 460 lb⋅ft (624 N⋅m) of torque at 6,300 RPM. These figures make it the most powerful naturally-aspirated production V8 engine of all time; the engine to previously hold this title, the Mercedes-Benz SLS AMG Black Series M159 6.2-liter V8, made 622 hp (464 kW; 631 PS) at 7,400 RPM. [7] [8] [1]

The LT6 is also the largest flat-plane V8 used in a production car by displacement, dethroning the Ford Voodoo. This is notable due to the additional vibrations inherent to this architecture compared to a crossplane V8, which tend to scale up with displacement. [9]

A modified version of the LT6 has powered the Chevrolet Corvette C8.R since 2019, and many features in the racing engine carry over to the road engine. [2] Other notable features include a cast aluminum block, dual coil valve springs supporting titanium intake & sodium filled exhaust valves, forged aluminum pistons, forged titanium connecting rods, active split intake manifold with twin 87mm throttle bodies, four-into-two-into-one stainless steel exhaust headers, and a factory six-stage 10-quart dry sump oiling system with individual crank bay scavenging. [1]

Applications:

Year(s)ModelPowerTorqueDyno Chart
2023–present Chevrolet Corvette Z06 670 hp (500 kW) @ 8400 rpm460 lb⋅ft (624 N⋅m) @ 6300 rpm link

LT7

The LT7 is a twin-turbocharged variant of the LT6 which debuted in the eighth-generation Corvette ZR1 and was unveiled on July 25, 2024. The LT7 has a redline of 8,000 RPM, generating 1,064 hp (793 kW; 1,079 PS) at 7,000 RPM and 828 lb⋅ft (1,123 N⋅m) of torque at 6,000 RPM.

The LT7 has stronger pistons and connecting rods, lowering the compression ratio from 12.5:1 to 9.8:1. Unlike the LT6, the LT7 uses both direct fuel injection and port injection, with a total of 16 injectors. The turbochargers produce up to 20 psi (1.4 bar) in normal operating conditions and a maximum of 24 psi (1.7 bar) under high temperatures. Other features specific to the LT7 include turbo-integrated exhaust manifolds, water-to-air intercoolers, and an electrically actuated wastegate. [10] [11]

Applications:

Year(s)ModelPowerTorque
2025–present Chevrolet Corvette ZR1 1,064 hp (793 kW) @ 7000 rpm828 lb⋅ft (1,123 N⋅m) @ 6000 rpm

See also

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References

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