The Time GM Almost Offered a 454-Powered C4 Corvette


The Time GM Almost Offered a 454-Powered C4 Corvette

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The experimental V12 Falconer C4 Corvette, known as “Conan,” has been having a bit of a moment lately since being highlighted by YouTube channel, Rockstar Rides. The 686 HP monster’s rekindled celebrity is well-deserved, but in the world of hopped-up C4 prototypes, there is another!

Behind the scenes, at General Motors in the late ’80s and early ’90s, there were several differing opinions about which direction to steer the C4 Corvette program. The King of the Hill was hitting showrooms, and there were teams fully dedicated to bettering the DOHC heart of the beast. Another group was focused on out Viper’ing the Viper with Conan’s twelve cylinders. Then there was Scott Leon, project coordinator at GM’s Arizona Proving Ground, and his dream of seeing big-block power return to America’s sports car.

While the former two groups ended up getting kneecapped by a three-headed monster of dwindling C4 sales (after moving 51,547 ‘Vettes in ’84, nearly 40k in ’85, and over 35,000 in ’86, the C4 only broke into the thirties one more time, just barely in 1987, before falling to 22 and change for ’88 and bottoming out at just over 20k in ’91 and ’92), high expensive bespoke engines, and a parent company in financial disarray; the latter faction, behind the leadership of Leon, could have delivered ZR-1 performance at a fraction of the cost.

Late after work one night, using a 1984 test mule that they had just laying around, Leon and his team set out to see if they could wedge a 454 cubic-inch Rat motor under the C4’s clamshell hood. It took some slight chassis mods along with the addition of a rigged-up tuned-port fuel-injection unit, an aftermarket tunnel-ram manifold, and Buick Grand National fuel injectors but, eventually, they were successful, and the “Big Doggie” was born.

The Time GM Almost Offered a 454-Powered C4 Corvette

Photo Credit: Remarkable Corvettes

Once the makeshift proof of concept was running, Leon presented it to GM brass and got the green light to build a pair of 454-prototypes. One used an automatic transmission 1986 coupe as a foundation and the second was a 1989 Z51 Convertible equipped with a six-speed and a clutch.

The Big Doggies made use of Chevrolet marine 454 short-block with L88 heads. To complete the build, the hood dome was raised slightly, the floorpan and frame rail were slightly modified, the convertible top mechanism was removed, and the hardtop was bolted to the body (a trick that would later be implemented on the C5 FRC and Z06). The completed feasibility studies were given the ZR-2 moniker, a name that had only seen the light of day on twelve individual 1971 Corvettes with the incredibly appropriate, special big-block handling package. The new ZR-2s were never put on a dyno, but engineers said that not only were they making LT5 levels of power, but they could also embarrass the fancy Lotus-designed eight with massive levels of low-end twist.

In the end, another three-pronged attack doomed the ZR-2 project. It was thought that offering similar performance with a desirable big-block powerplant at a much lower price would undermine GM’s sizeable investment in Lotus, the LT5, and the ZR-1. There were also emissions requirements and the same financial problems that initially got the C5 program canceled to consider. Offering the ZR-2’s 454 in the performance parts catalog as an engine swap kit was also briefly considered, but it never came to fruition.

An alternate universe where the fourth rendition of the crossed flags featured a 32-Valve masterpiece, a 12-cylinder supercar fighter, and the return of the big-block V8 is a place all Corvette fans would love to visit but, here in our present; we can take solace in the fact that a classic displacement did fight its way back from the dead in the C6 Z06 and there are some truly unique and magical things on the horizon for an eighth-generation car that likely wouldn’t have happened with any other series of events than the one we got.


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  1. So, what happened to the two “Big Doggies”? Do they still exist? If so, does anyone know where they are and who owns them?

  2. Great question, Doug! Whereabouts didn’t come up in any of my research. If anybody knows where the doggies ended up, please drop a knowledge bomb in this section!

  3. Must have been fun working on projects like this. I worked for Pratt and Whitney in product development. Some projects were exciting to do too. Not like corvettes for sure.

  4. Chevrolet was going to offer the 460 hp 454 (LS7) in the 1970 Corvette. This engine made at least 560 hp, ended up only being sold in crates to people like me, zoom zoom.

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