The eighth-generation “C8” Chevrolet Corvette, which first debuted in 2019, is nothing short of America’s supercar. The C8 embodies a seldom-seen rear-mid engine layout, along with a powerful V8, which enabled it to make waves when it first hit the road. It has since consistently delivered incredible performance for its value. Since its original rollout, Chevy has been teasing an even higher-performance variant, and now, the world is getting exactly what it has been waiting for in the form of the Corvette Z06.
At the core of its ruthlessness is a high-revving, naturally-aspirated 5.5-liter V8 engine that produces an astounding 670 horsepower at 8,400 RPM, and 460 pound-feet of torque. In fact, General Motors says that the LT6 engine found in the C8 Z06 is the most powerful naturally-aspirated V8 in a production car, period.
It certainly sounds the part, too. The new Corvette Z06’s rear-mounted V8 spews visceral exhaust notes like one would expect to hear come from the tailpipe of an exotic sports car, such as a McLaren P1, Ferrari F430, or Lotus Esprit. And there’s a reason for that. It starts with a key component found within the Z06’s V8 engine that is also shared with all of those legendary cars.
To better understand what makes the Z06 such a special addition to the Corvette lineup, it helps to head to the back of the car and pop the hatch. Nestled just in front of the rear wheels is the LT6 engine—the real star of this Corvette’s mechanical symphony. While this might just look like any other V8, its flat-plane crankshaft makes all the difference.
Each piston inside of a motor is attached to the engine’s crankshaft via a connecting rod. The piston is responsible for compressing air and fuel to be ignited, and is both balanced and timed by the crankshaft. The connecting rod clamps to a smooth, oiled cylindrical surface on the crankshaft called a crankpin, which enables the piston to be raised and lowered inside of an engine’s cylinder as the crankshaft rotates.
Crankpins are evenly spaced along the length of the crankshaft—one crankpin for each cylinder. On a normal crossplane crankshaft found in a traditional V8 engine, each crankpin (along with a corresponding counterweight mounted opposite of it for balance) is rotated around the crankshaft, positioned approximately 90-degrees from another. Think of this like evenly spacing weights along the equator of the Earth to maintain balance. This spacing creates both a primary and secondary point of balance along the crank’s rotational axis. As a result of all this, an engine with a crossplane crankshaft is better stabilized and has decreased noise, vibration, and harshness.
However, comfort comes with some tradeoffs. A crossplane crankshaft achieves additional balance by placing the aforementioned counterweights on the crankshaft across from each crankpin, meaning that the crankshaft is often larger and the rotational mass of the fastest-moving part in the engine is increased. Heavier rotational mass means a less responsive engine, and a larger crankshaft means less compact engine packaging.
Meanwhile, this Corvette’s flat-plane V8 is essentially two inline four-cylinder engines mashed together with only one primary point of balance on the rotational axis. This configuration (along with aluminum forged pistons and titanium connecting rods) allows for lighter rotational mass with shorter strokes—the distance that a piston travels from top-dead center to the bottom of the cylinder—and as a result, can typically rev significantly higher, significantly quicker than an engine equipped with a crossplane crankshaft.
Source : https://www.popsci.com/technology/chevrolet-corvette-z06-review/
