The body sides also take on more of a Pontiac-like appearance. The rear quarter-panels are unique, with a skeg that gives this Poncho more of a Coke-bottle appearance than the Corvair, and that line extends to the tail. Simulated brake-cooling vents, similar to those on the '67-'68 Firebird, are used.
The Pontiac Polaris roofline is different than its Chevy counterpart. The '65-'69 Corvair used a revised version of the '61-'62 full-sized GM bubbletop design, but the Polaris takes a slightly different approach, using a fastback roofline with extended C-pillars that sweep back to the tail. From the side, our vaporware Polaris resembles John Fitch's Corvair conversion, which interestingly, was called the Sprint. The back light is flush with the C-pillars, unlike Fitch's flying-buttress design.
The revised roofline necessitates a raised rear deck. Between the rear glass and the engine-compartment decklid is a louvered black panel that allows additional cooling air to the engine. The tailpanel is slightly tunneled and houses slotted lamps, a Pontiac design icon. Add a set of Rally I wheels, Polaris block lettering, and redline tires, and the look of Pontiac's Z-body is complete.
What about the powertrain? How could such a uniquely Chevy engine design be made into a credible Pontiac powerplant? Simple. The same way that Pontiac engineers, led by the legendary Malcolm R. "Mac" McKellar, took the lowly Chevrolet six and made it the Sprint—an overhead cam (OHC) conversion.
McKellar had long been enamored with OHC engine layouts, and this short-stroke boxer engine would be a natural for it. Chevy built a similar engine for the Chevy Astro I show car as part of an experimental modular-engine program, so the idea was already making the rounds.
In this Pontiac version, we add a McKellar-style belt-driven overhead-cam system with hydraulic-cam followers. The system is topped with signature finned Pontiac cam covers. Like the Pontiac OHC-6 engine that was produced from '66-'69, our take on the Polaris is offered in two versions, both in a 3.2L configuration, up from the Corvair's 2.7L displacement. The extra cubes come from a 3.75-inch bore size to complement the stock 2.94-inch stroke.
Like its Corvair counterpart, our Polaris' base engine uses a one-barrel carburetor on each bank of cylinders, with mild cams and a single exhaust. We estimate 165 horsepower, which makes for a responsive, economical street car.
The Polaris Sprint option is an aggressive, performance-oriented American version of a Porsche 911. The 3.2-liter six features hotter camshafts, 10.75:1 compression, and Pontiac's Tri-Power system, but with a twist. Where Pontiac's 389s and 421s used three two-barrel Rochester 2 GC carbs, this version uses two three-barrel carbs, one carb per bank.
The carbs themselves are similar to Weber downdrafts but use standard Rochester internals in specific three-barrel main bodies. (Carbs of that type were actually developed by GM, but were abandoned when the Corvair was scheduled for cancellation.) Round out the combination with free-flowing manifolds and a dual-exhaust system, and you have a sweet combination.
With its free-revving valvetrain and ample carburetion, the flat-six would put out somewhere north of 200 horsepower, with a rev range that wouldn't be afraid to tip 7,000 rpm. Couple it to a close-ratio four-speed with 3.73 gears, a quick-ratio steering box, and a hefty set of front and rear sway bars, and you have just the ticket for sport-car fans looking for something exciting from this side of the pond.
I wonder if DeLorean ever regretted his decision to back away from the Polaris concept? The second-generation Corvair was a beautiful car, and I think he would have appreciated it. By the time he took over as Chevrolet general manager, however, the Corvair was cancelled.
Had the Polaris gone into production, it is likely the Y-body Tempest would not have happened. The GTO might not have been introduced for the '64 model year, and we might not be celebrating its Golden Anniversary now.
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