Flat-plane V8s are neat. But the LT6 is more than just your typical flat-plane V8.
Little by little, GM has been taking us to school on the new Corvette Z06. The brand's YouTube series called Corvette Academy covers some of the more technical aspects of the Z06 via interviews with the team that built it, including chief engineer Josh Holder, system engineer Yoon Lee, and Sports Car Racing Program manager Laura Wontrop Klauser.
This week, Chevy dives deep into what makes the Z06's 670-horsepower flat-plane crank V8 so special. In short, there's a lot, with tons of cool easter eggs baked in. Among those, Chevy also used to provide 'Vettes to astronauts in the space program, which led to a little rocket being stamped on the engine. Chevy nicknamed the engine "Project Gemini," for the astrological twins, which not only relates to the NASA space program but also describes much of the engine. The LT6 has twin intake plenums, twin exhaust and intake valves, two cams, and the list goes on. But there's much more at work here.
The LT6 V8 engine shares no parts with any engine GM has ever built, which already makes it incredibly special. "We wanted to get back to our naturally-aspirated roots," says Holder. "An N/A engine gives the driver feedback in a way that a supercharged engine [like the one in the last car] just doesn't," he continued. Still, the team had to outdo the last car in terms of performance.
They did so by creating an engine that can breathe more. To do that, you need more air, and more revs, which led them to the flat-plane configuration. A flat-plane engine can rev higher because much of it is lighter than a pushrod V8 with a supercharger. Those lighter parts mean those same parts can move faster, leading to higher revs.
"What allows a flat-plane V8 to spin and rev so quickly... is that you have very low inertia in the crankshaft and essentially the entire cranktrain [pistons, connecting rods, crankshaft, flywheel]," says Lee. "You're able to reduce the size of the counterweights compared to a cross-plane." The result is a high-revving engine capable of producing more power because those revs feed in more and more air.
Chevy had been testing this engine layout in the C8.R racer for two years, according to Wontrop Klauser. "We put that in the race car to make sure it would give us everything we needed," she continued. Both years those cars took home both the driver's and a manufacturer's championship.
Among the tons of cool details to be gleaned about the motor, one of them is the specialized induction system. Lee says there are three tuning valves within the LT6's manifold that allow for variable volume in the intake manifold, which allowed the team to extract the most power across the entire rev range and tune the sound of the engine sublimely.
Additionally, the fuel injectors are on the exhaust side of the combustion chamber, likely to improve the air-fuel mixture's efficiency. The high volumetric efficiency of the engine as a whole leads to better power outputs, with a high redline (8,600 rpm) that becomes enjoyable to chase, time after time, straight after straight.
All that said, the new Corvette Z06 is set to be something special. Holder describes the LT6 as "like an F1 car" in its throttle responses, which is certainly high praise from an engineer. We can't wait to see what the results of all this work are.