- The 2023 Corvette Z06 is finally here, powered by a new 5.5-liter V-8 engine with a flat-plane crankshaft.
- It is equipped with an eight-speed dual-clutch automatic transmission and produces 670 horsepower and 460 pound-feet of torque.
- Production is scheduled to begin in the summer of 2022.
Tadge Juechter, Corvette executive chief engineer, is forthright about the real reason why America's sports car was redesigned with a mid-engine layout: "When we went mid-engine, the justification for it was that it wasn't the standard car." However, while the mid-engine architecture works well for the 10Best-winning Stingray, the larger motivation for a new platform with the engine in the middle is the 2023 Corvette Z06, a winged wide-body supercar that is aimed squarely at the enthusiast's hearts.
As Juechter explains, "the higher-horsepower cars benefit the most from having all of that traction in the back." As for power, its 670 horsepower double overhead cam (DOHC) 5.5-liter V-8 is the most powerful naturally aspirated V-8 ever installed in a production vehicle, surpassing the 622-horsepower 6.2-liter firebreather that powered the 2014 Mercedes-Benz SLS AMG Black Series.
Because it sounds like Recaro suddenly appearing with a saddle when a naturally aspirated engine is introduced in today's turbocharged and electrified world, it's likely that you haven't heard the 9000-rpm call to prayer from the Porsche 911 GT3's 4.0-liter flat-six engine. When Chevrolet introduced the previous Z06, supercharging increased power. However, the company received significant feedback suggesting that the Z06 should return to the purity of the high-revving LS7 from the gen-six Corvette. Going naturally aspirated is for drivers who understand the difference and crave a unique sound experience as well as a direct connection that turbocharged and hybrid vehicles simply cannot provide. There is no manual transmission; Chevrolet did not go that far and instead opted for an eight-speed dual-clutch automatic transmission. While we haven't had a chance to get behind the wheel of the Z06, we have heard its engine. It caused the hair on the back of our necks to stand on end. If it doesn't have the same effect on you, we recommend that you ask for Highlights for Children during your next dental appointment. Tony Quiroga is the author of this piece.
The LT6 is introduced
Chevrolet claims that the new LT6 engine in the Z06 is a completely new design, and for the most part, they are correct. However, there is one specification that remains the same: the 4.4-inch bore center. In all Chevy small-block V-8s, this dimension, which defines the distance between the piston centers within a cylinder bank, is shared by the piston centers. Even the last DOHC engine to power a Corvette, the LT5 from the C4 ZR1, which featured a Lotus-designed head, had 4.4-inch bore center spacing.
It doesn't matter that LT6 is an engine code that was shared with a 4.3-liter V-6 Oldsmobile diesel that was only available for a short time. The new LT6 is a machine that will go down in history. Every engine will be put on a dyno and run through a 20-minute break-in period before being tested to ensure it is operating as advertised before being installed in a new Z06. This will be a first for General Motors.
There is a 670-horsepower rating and a 460-pound-feet of torque rating for the engine, with the horsepower peaking at 8400 rpm, which is right around the 8600-rpm fuel cut. It is no coincidence that Ferrari V-8s produce their maximum power right at the redline. More revs equal more power in the LT6, and the engineering team will squeeze every last rpm out of the engine.
To develop a new engine with a short stroke and a large bore in an industry obsessed with electrification and efficiency is risky, but General Motors is taking a chance. The cylinder's internal dimensions are 104.25 millimeters by 80.0 millimeters, resulting in a displacement of 5.5 liters on paper. In this case, the compression ratio is 12.5:1. The brake mean effective pressure is in excess of 1400 kilopascals, which is great news for the engine geeks.
Despite the fact that the C8 team could have easily installed a pushrod V-8 with a blower on top, a supercharged engine does not have the same character as a flat-plane-crank engine. In the course of development, General Motors swapped out its Ferrari 458 for the turbocharged 488, and the team agreed with our assessment that some of the magic had been lost. As a result, they purchased another 458.
Flat-plane cranks, on the other hand, are not a perfect solution. This is something that Mustang Shelby GT350 owners, who have a high-revving 5.2-liter V-8, will understand. They tremble a great deal. So much so that, during the LT6 development process, an oil filter reversed itself on a test bench. Engineers suspected that a technician had not tightened the bolt, but video evidence revealed that there was no wrongdoing. The solution consisted in switching from a screw-on to a cartridge filter configuration.
Titanium connecting rods and intake valves are used to keep reciprocating mass to a bare minimum in order to keep those forces at bay. Sulfuric acid is used to fill exhaust valves. All 32 valves are equipped with two springs per valve to prevent valve float when the engine is running at high speeds. When assembled, direct-acting finger followers have a diamond-like coating and are shimmed to ensure proper alignment. Jordan Lee, General Motors' global chief engineer for small-block engines, describes himself as "lash for life."
Because of the CNC-machined DOHC heads, the engine is significantly larger than its pushrod counterparts. Height and width were more tightly restricted in the C7 engine because increasing either of them would have resulted in an increase in hood height or footwell width, respectively. Because the engine is located behind the cabin, those dimensions aren't as important. In addition, given that the C8 was built around a specific engine length, we can understand why engineers decided to keep the small-bore block's spacing.
The block is equipped with what General Motors refers to as a "dedicated lower crankcase." Each crank journal is housed in a sealed bay, similar to how Ferrari constructs dry sumps for their engines. There are six oil scavenge pumps on the ship: one in each bay and one in each head of the ship's engine.
A total of two plenums, two 87-mm throttle bodies, three valves that connect the plenums, and eight beautiful trumpets are included in the intake system. Those crossover valves fine-tune the intake to provide optimal performance at both high and low rpm.
Direct fuel injection is the logical choice in this situation. In contrast to the Indy V-6, which has injectors located on the intake side of its heads, near the valley of the vee, the Chevrolet Indy V-6's injectors are located between the exhaust valves, a design borrowed from Chevy's Indy V-6. It helps to promote tumble by spraying fuel into the incoming intake air (the motion and mix of air and fuel). More tumble results in better burn.
V-8s with flat-plane cranks are a visceral experience. The intake sound reminds us of the sounds of our childhood and draws us in like a siren song as we grow into our adult selves. After hearing a Corvette C8 Z06 start for the first time, your entire body will snap around, much like a kid being called into dinner on a hot summer night.
Wheels, wings, and other accessories
No one could possibly describe the standard C8 as being monotone in any way. While talking about "scalpelizing" and "sharpening" the Z06 in order to create the purest-driving Corvette ever, the engineering team makes it sound as if the Stingray were a '70s muscle car.
Their goal is to provide a driving experience that is as urgent as a high-revving engine, but that is also approachable while also possessing an incredible depth of capability that a driver can continue to unlock with dedication and skill over time. More rigid engine mounts transmit greater amounts of the engine's vibration and character to the driver's backside, while also allowing for quicker and crisper shifts from the Tremec eight-speed dual-clutch automatic transmission, which is standard. For the first time, the Corvette's spring rates are so stiff that helper springs are required to maintain proper check load when the car is operating at full jounce. Moreover, control-arm bushings have been significantly stiffened, with upper units that are "nearly as stiff as a spherical bearing," according to Alex MacDonald, vehicle-performance manager.
Interestingly, MacDonald claims that the Z06 deviates from the recent trend of having track tires that perform their best during the first couple of laps of the race. The Corvette team collaborated with Michelin to develop a new version of its Pilot Sport Cup 2 Rs tires specifically for the Z06. It has been reported by MacDonald that development drivers are achieving their best times after ten laps.
Forged aluminum wheels are used on the Z06's 20-inch front and 21-inch rear wheels. Carbon-fiber wheels, such as those manufactured by Carbon Revolution, are available as an option. In addition to lowering unsprung weight, they are significantly stiffer, allowing engineers to fine-tune the steering and magnetorheological dampers to better suit their requirements. That's correct; the calibrations are specific to each wheel, and according to MacDonald, the carbon wheels result in a significant improvement in lap time. In addition to the standard fender flares that accommodate the 275/30ZR-20 front and 345/25ZR-21 rear tires, the Z06 is distinguished by distinctive front and rear fascias.
The primary reason for the Z06's taller wheels is to accommodate the vehicle's significantly larger brakes. Iron rotors are standard, measuring 14.6 inches in front and 15.0 inches out back, which are 2.0 and 1.2 inches larger than the Z51 Stingray's rotors, respectively. Carbon-ceramic rotors measuring 15.7 and 15.4 inches in diameter are included in the Z07 package.
Because the C8's mid-engine body is more aerodynamically efficient than the previous ZR1, the Z07 package's relatively low wing produces significantly more downforce and significantly lower drag than the giant wing on the previous ZR1. A front splitter and canards are used to improve high-speed stability and cornering, but none of the aerodynamic elements are in use at the time of the crash.
The numerous changes to the Z06 have piqued our interest, and we can't wait to get behind the wheel and rip around in it. That opportunity, on the other hand, will not present itself until early next year.
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