Special features in the C8 Corvette Z06’s LT6 V8 highlights:
- The LT6 V8’s codename was inspired by NASA rockets
- It’s a small-block V8 with racing-style exotic materials, construction methods, and motorcycle-like mechanical finger followers in its valvetrain
- The C8 Corvette Z06 manages air and oil not just to make power, but also to keep cool and sound great
Even before the rise of electrification, cars—or rather, supercars like the upcoming 2023 C8 Corvette Z06 were rare. And while the C8 Z06 should be a thrilling ride—just ask Jay Leno—we already know that it sounds thrilling. That’s thanks to the incredible piece of engineering sitting just behind the driver: the 5.5-liter flat-plane crank LT6 V8. But though a flat-plane crank is unusual to see in an American V8, it’s just one of several cool features and details that make this engine special.
Chevrolet calls the LT6 V8 ‘Gemini’ because this thing’s a rocket
A cutaway 2023 C8 Corvette Z06 LT6 V8 | Matthew Skwarczek, MotorBiscuit
With 460 lb-ft of torque, the 2023 Corvette Z06 is slightly less torque than the standard C8 Corvette Stingray. But with 670 hp on tap, it’s significantly more powerful. That figure also officially makes the LT6 V8 the most powerful naturally-aspirated production engine ever. And Chevrolet is celebrating that status with a little Easter egg.
In the past, Chevrolet often gave NASA astronauts special lease deals, which started a long association of space flight and Corvettes, MotorTrend explains. So, when it came time to choose a code name for the high-power LT6 V8, the engineers turned to spaceflight for inspiration. They chose ‘Gemini,’ as the LT6 has many twin components, which we’ll discuss shortly. And they commemorated the name by stamping a little space rocket onto the engine.
Or rather, several rockets. The LT6 V8 has 54 tiny rockets scattered throughout its parts, from the block to its pistons. Why 54? It could be a coincidence, but Autoweek reckons it’s a reference to the original Chevy small-block V8’s 1954 debut.
The C8 Corvette Z06 couldn’t rev like a Ferrari with pushrods or hydraulic valves
Nerd out with us as we dive into the nitty-gritty technical details of GM's LT6 flat-plane-crank V8 used in the new Chevy Corvette Z06 https://t.co/Ks8eOPywiC
— Roadshow (@roadshow) February 23, 2022
Yup, you heard right, the LT6 V8 is technically a Chevrolet small-block engine. Admittedly, the differences between small- and big-block engines are mostly academic these days. Nevertheless, like the base C8’s LT2, the LT6 is a small-block V8.
However, the only thing it shares with that engine is its bore spacing. In a significant break from Corvette tradition, the C8 Z06 doesn’t have pushrods to operate its valves. Instead, like the C4 ZR1, it has dual overhead cams. It has five camshafts, though: four for the valvetrain and one to turn the dual fuel pumps.
And speaking of valves, the LT6 doesn’t have the typical hydraulic valve lifters/tappets you see in basically every car. It revs so fast and high that, as with most motorcycle engines, hydraulic lifters couldn’t keep up. They also added weight; and because flat-plane crank engines tend to shake themselves apart, ‘unnecessary weight’ is a big no-no.
However, unlike some past revvy racing-inspired engines, the LT6 V8 doesn’t have the usual mechanical bucket-and-shim tappet arrangement. Instead, it uses something only seen on racing bikes and a handful of high-end sportbikes: finger followers. These steel levers let the camshaft lobes consistently actuate the valves even at the LT6’s 8600-RPM redline. And not only are they lighter than traditional mechanical tappets, but thanks to a diamond-like coating (DLC) and dedicated oil jets, they’re far more durable.
But if you think this mechanical valvetrain setup means valve adjustments are back, think again. GM says the lash (clearance) stays consistent throughout the C8 Corvette Z06’s lifespan. And it’s checked three times during the engine-build process. Also, fun fact, you can request to help with that process at the Corvette factory, Autoweek says.
The LT6 V8 is made with race car materials and techniques—and some talc
2022 C8 Chevrolet Corvette LT2 V8 combustion chamber close-up | Matthew Skwarczek, MotorBiscuit
That DLC on the finger followers isn’t the only exotic material you’ll find in the LT6 V8. And the finger followers themselves aren’t the only racing-inspired pieces of technology, either.
For example, its exhaust valves are hollow steel filled with sodium, while its intake valves are titanium. It has titanium connecting rods, too, as well as forged-aluminum pistons. Those pistons are shaped differently based on which side they’re on, though they all have DLC rings and polymer-coated skirts.
In addition, the LT6 V8’s two-piece block is sand-cast out of aluminum alloy. But because sand casting often leaves rough surfaces, Chevrolet filled in those tiny open spots with talc, MotorTrend explains. This talc trick also helped smooth the LT6’s various oil and air passages.
Sand casting and two-piece blocks are common sights in the racing world. So is deck-plate honing, wherein special plates are attached to the block parts during assembly. These ‘torque plates’ mimic how the cylinder heads minutely warp the bores. A boring machine then re-hones the cylinders, so when the block is fully assembled, all the cylinders are perfectly circular. It’s not unique to the C8 Corvette Z06—Chevrolet does this on the Camaro ZL1—but it’s a very rare procedure for a street engine.
Though considering how much the LT6 V8 shares with its racing incarnation, that’s arguably not that surprising.
This small-block V8 lets air and oil flow fast
2023 Chevrolet Corvette Z06 LT6 V8 piston, crank, and oil scavenging pump close-up | Matthew Skwarczek, MotorBiscuit
You can’t make 670 hp reliably without managing airflow, and not just because combustion requires oxygen. Air also helps manage heat, something C7 Corvette Z06 owners know all too well. Fortunately, the C8 Corvette Z06 manages both well thanks to some nifty features.
Earlier, I mentioned that the LT6 V8’s Gemini code-name stems in part from its multiple ‘twin’ features. For instance, it has dual overhead cams, dual valve springs, and dual fuel pumps. But the LT6 also has dual throttle bodies feeding dual high-flow intake plenums. Those plenums are part of an active intake manifold that also incorporates three tuning valves that continuously vary air volume and resonance. And once the air finishes circulating, it’s sucked into the combustion chambers via eight intake trumpets.
As for the temperature control part, the C8 Corvette Z06 has 50% more cooling capacity than a Z51-equipped C8 Stingray, Autoblog reports. That’s thanks to five radiators with upgraded cooling fans. Plus, for the serious track-day owners, the Z06’s front bumper has a removable panel that increases the grille’s opening by 75% for even better cooling.
Air isn’t the only thing that helps manage heat, though. Oil is vital for reducing friction, keeping things clean, and absorbing excess heat. But maintaining proper oiling in a flat-plane-crank engine isn’t easy. Early LT6 V8 prototypes vibrated so much that their spin-on oil filters spun themselves loose. Hence why the final version has a bolt-on filter.
Besides a different filter, the LT6 V8 also has a completely different oiling system than LT2. Firstly, it doesn’t have a separate oil pan; the lower crankcase acts as one, MT explains. Secondly, the LT6 has a true dry-sump system with a sealed bay, separate oil tank, and six scavenging pumps (which look like bundles of gears). All these features maximize oil circulation and minimize air intrusion, frothing, and power loss. And yes, the C8 Z06 has a dedicated oil cooler.
The C8 Corvette Z06’s LT6 V8 doesn’t make fake noise
2023 C8 Chevrolet Corvette Z06 exhaust tips | Chevrolet
Although it’s not the newest Ferrari, Chevrolet engineers benchmarked the 458 when developing the C8 Corvette Z06. The team found and bought a crashed 458 in Poland just to study its flat-plane-crank design. Also, it felt that the 458’s turbocharged successors, the 488 and F8, didn’t have enough soul.
Much of that soul stems from the noise the LT6 V8 shoots out its exhausts. And GM didn’t want to cheapen the experience by relying on artificial exhaust-note amplification. Instead, the C8 Z06’s exhaust tips have special bezels that reflect sound waves towards the cabin. The volume is turned up, but the noise is all-natural.
Furthermore, the C8 Z06 doesn’t have a conventional two-mode sports exhaust. Rather, it has a continuously-variable exhaust with programming that varies between the three driving modes, MT says. Plus, the muffler weighs 20 pounds less than the stock Stingray one, Autoblog notes.
When will this engine shriek on the road?
What’s even more incredible than this V8’s tech is how (relatively) little it will cost. The 2023 Chevrolet Corvette Z06 should start at roughly $87,000 when it goes on sale. And that day is coming soon: production starts in summer 2022.
A word of warning to future Z06 owners: be prepared for geek-out sessions.
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Keyword: 5 Incredible C8 Corvette Z06 LT6 V8 Details Beyond Its Flat-Plane Crank