When did Chevrolet build the first supercharged Corvettes? I would have answered C6 ZR1 in 2009. Or maybe recalled some of the engineering prototypes with turbochargers in the 70s and 80s. Or some of the specialty shop builds, like Callaway, Hennessy, or Lingenfelter, and occasionally available as Regular Production Options, and there was a McCulloch-supercharged ’53.
But, I wouldn’t have answered 1957, with a factory-engineered, GMC-supercharged, Rochester fuel-injected small block Chevy for Corvettes.
Apparently, in 1957 Chevrolet adapted a GMC 4-51 supercharger to install on top of a modified ’57 fuel injection manifold, with production-based ’57 GM Rochester F.I. components: air meter/throttle valve, fuel pump, fuel meter, and injectors.
GMC (General Motors Corporation) made Roots-type superchargers for use with their two-stroke Detroit Diesel engines that were popular in trucks, buses, and locomotives for decades. Yes, a two-stroke diesel, and they sounded like they were revving like crazy because they had a power stroke for every crank revolution. But unlike small two-stroke engines for chain saws, etc. the Detroit Diesels had a conventional crankshaft with plain bearings in an oil sump crankcase, like a four-stroke engine’s crankcase. Instead of using the crankcase to pump air in and out of the engine like a chain-saw two-stroke, GMC used a Roots blower to pump volumes of air that essentially matched the engine’s air consumption needs. And these GMC diesels used conventional poppet valves instead of ports in the cylinder. Why a two-stroke Diesel? Because you get a power stroke every rev instead of every other rev like a four-stroke engine. So, potentially, they obtained more power from a given engine size compared to a four-stroke Diesel.
GMC/Detroit Diesel made these two-stroke diesels in many size and cylinder configurations. You probably remember the big GMC 6-71 blower, long a favorite among top fuel dragster racers. The 6-71 came from a six-cylinder Detroit Diesel with each cylinder displacing 71 cubic inches. The lesser-known 4-51 blower that was adapted to these experimental ’57 small-block Chevies were originally designed for a four-cylinder Detroit Diesel with 51 cubic inches per cylinder – a size I was not familiar with. These GMC blowers were rugged, built for a million miles of tough commercial trucking and railroad duty.
Apparently, the Chevrolet engineers had a small number of castings made to adapt this blower onto the 283 and one of them might have been used by Zora Arkus-Duntov for a Pike’s Peak record attempt – where the blower would help overcome the power loss caused by thin air at Pike’s Peak’s elevations of up to 14,000 ft.
I cannot recall ever seeing any info on this factory supercharging effort, but apparently there was a February, 1980 article in Super Chevy magazine that told the story and published some of the Chevrolet engineering reports and dyno charts.
There are at least two C1 Corvettes running with this supercharged engine configuration. You can see these cars, and under their hoods (BTW one of them has a C6 ZR1 window installed in the ’59 C1 hood) here:
Zora’s Supercharged C1 Corvette Prototype Engines Are Still Alive and Kicking – CorvetteForum
And here is a link to an additional video of this system installed in a ’62 Corvette with driving ‘footage’:
Rare Supercharged 1962 Corvette: Pure American Muscle Unleashed
Looks pretty torquey to me! Torquey enough to damage the stock trans and rear axle.
Makes me wonder how the Corvette story might have changed if this supercharged, fuel injected combination had made it into production. Maybe much-needed disc brakes would have been adapted well before 1965. Maybe there would’ve been more motivation to provide better tires, sooner. Maybe the big-block wouldn’t have made it into the Corvette. Or maybe the big-block wouldn’t even have been needed in any Chevy car.
