Latest C8 ZR1 Teaser Appears to Confirm 5.5L Gemini V8!

A twin-turbo 5.5L Gemini V8 will likely power the C8 Corvette ZR1, but does it feature a cross-plane or a flat-plane crankshaft?

Chevrolet started this week off right — with a screaming V8. The company dropped a second teaser video (below) for the forthcoming C8 Corvette Zr1, which is set to debut sometime this summer. The first teaser, launched in April, used computer graphics to hint at the C8 ZR1’s side profile, large wing, and more aggressive front end. Today’s computer-generated teaser focuses mainly on the ZR1’s center-exit quad-tip style exhaust and a glorious V8 soundtrack. But not just any V8 soundtrack. A 5.5L Gemini V8 soundtrack.

Careful viewers will note that, right around the 10-second mark in the teaser, a familiar rocket rises through the swirling mist out of the ZR1’s exhaust plume. A rocket that first debuted as an easter egg on the 5.5L LT6 V8 — codename Gemini — from the C8 Corvette Z06.

This particular rocket logo and the Gemini codename are a callback to the 1960s NASA space program and its long association with the Corvette brand. Thematically speaking, the LT6 V8 is a bit of a moonshot, in that it’s the most powerful naturally aspirated V8 engine of all time at 670 horsepower. And the very first Corvette to feature a flat-plane crankshaft. Today, Chevrolet appears to have confirmed that the ZR1’s engine is going to be the second member of the Gemini engine family.

Center-Exit, Twin Vortices

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But what type of Gemini V8 should we expect? If the rumors are to be believed, the LT7 should be a twin-turbocharged version of the LT6, flat-plane crank and all. Looking at today’s teaser video, the very first moment features a CGI Corvette passing under the camera, highlighting the quad-tip exhaust and leaving behind twin vortices in its wake that certainly look like swirls of turbocharged air.

There’s also the matter of the exhaust layout, which adds more confirmation a 5.5L Gemini V8. How so? Across the C8 generation, Chevrolet has, thus far, used an outboard-style exhaust for its 6.2L LT2 V8 powered models (Stingray and E-Ray) and a center-exit quad-tip exhaust for all 5.5L V8 powered models (the production C8 Z06 as well as Corvette Racing’s C8.R and Corvette Z06 GT3.R). It appears this trend will continue.

Unthinkable Speed

Historically, the ZR1 nameplate represents the ultimate Corvette of a given generation. The C6 Zr1 was the first supercharged Corvette in history, and the C7 Zr1 remains the most powerful Corvette in history, with 755 horsepower. So expectations are quite high. Especially with GM settling on the word UNTHINKABLE to describe its new ultimate Corvette.

But what does Chevrolet mean by “unthinkable speed,” exactly? We’ll find out soon, of course. And there are many details we don’t know like, will the c8 ZR1 be rear-wheel-drive like the Z06 or all-wheel-drive like the E-Ray? But at first glance, here are two possible benchmarks for the Zr1 to obliterate when it debuts. The current C8 Corvette E-Ray is the quickest factory Corvette to 60 mph (2.5 seconds) and in the quarter mile (10.5 seconds). And the C7 Zr1 is currently the fastest Corvette in history, having certified a 212.49 mph top speed, an average calculated after two runs in two different directions to account for wind. (Chevrolet also limited the ZR1 to 215 mph for tire safety.)

Will the C8 ZR1 be the first factory Corvette to run 9s in the quarter mile and see 220 mph?

Flat-Plane vs Cross-Plane Crankshafts

The last bit of debate surrounding the LT7 involves the crankshaft question. As a refresher, outside of the LT6 from the C8 Z06, every other Corvette V8 in history has used a cross-plane crankshaft, which features “four crank pins that are positioned in two planes, offset by 90 degrees.” This produces the sound of the traditional American V8 that has run from the original small-block Chevy to the current C8-generation LT2.

A flat-plane crank features “all of its crank pins in a single, flat plane,” which allows it to rev higher and faster than typical V8s. But keep in mind that most boosted flat-plane-crank engines have relatively low displacement (at or below 4.0L), which reduces the mass of all the rotating parts. The LT6 is not only the most powerful n/a V8 ever, but also the largest, which poses extra challenges for the engineers.

To my ears, listening to the two C8 ZR1 teasers again and again, it’s not a slam dunk either way. The engine note isn’t as high as the Z06’s banshee wail exhaust note. But anyone who has ever heard a turbocharged V8 will tell you that turbos muffle a lot of sound. And, to my ears, the exhaust note lacks the growl you’ll hear with cross-plane crank V8s (stuff like twin-turbo Audis and Porsches).

So my personal wager is that the rumors have long been true. 5.5L twin-turbo flat-plane crank V8. What do YOU think, dear reader? Twin-turbo flat-plane-crank? Cross-plane-crank? Rear-wheel-drive or All-wheel-drive? Let us know HERE in the forums!