Pontiac's famous X-400 show cars ended their run with the '64 edition, and we resurrected the concept for a one-off, never-built '66 version, as seen in an earlier edition of What If? This time around, we move the idea for an X-400 show car to the '76 model year.
First we will reinterpret the concept of what constitutes a X-400 in order to fit the historical context of the era.
The X-400s were luxurious, supercharged convertibles, but by '76, the convertible market had dropped off significantly and GM was busy marketing the '76 Eldorado as the last convertible. Looking back at the idea from the mindset of today, a convertible is a great idea, but it just doesn't fit with where the market was at the time. Instead, we envision the '76 X-400 starting with a solid-roof Grand Prix. It was a great model year for the Grand Prix, with sales totaling 228,091, setting a record that would be broken the following year, but never again.
Now let's add some performance overtones. Some historians and hobbyists would argue the Grand Am already fit that bill admirably, but it did not return for the '76 model year, and the Can Am did not reach the market for another year. The '76 X-400 closes the gap for a performance-oriented mid-sized car, even if it is only a one-off show car.
Up front, the X-400's performance image is accentuated with a semi-gloss blacked waterfall grille and headlamp bezels. A custom front air dam, housing a pair of Cibie driving lamps, flows into the Trans Am-inspired front wheel foils. A pair of X-400 callouts on the front fenders lets everybody know this is not just any Grand Prix. Trans Am fender extractors give the underhood air pressure an escape hatch and provide a racy touch. The rear wheel wells are treated to Trans Am-style wheel foils, and louvered quarter windows, hooded sport mirrors, and engine callouts mounted in the rocker mouldings add to the show car's performance intentions.
The stock hood sports a functional Shaker scoop and feeds a very special powerplant: a 10-psi, turbocharged Super Duty 455. Using existing '70s technology, the turbo system is a draw-through design that is similar to, but significantly larger than, the systems used on the later 301ci Turbo V-8s. A water-alcohol injection system provides charge cooling. An 800-cfm Rochester Quadrajet is employed.
Measured at the crank, 575 horsepower feeds through a specially modified Turbo 400 with a slightly looser than stock converter, which allows for the engine to build boost while brake standing. The stock rearend sports 3.08 gears and Safe-T-Track, both sourced from Pontiac's parts bin. The front suspension is upgraded with shocks, springs, steering box, front and rear sway bar, and bushings from the LeMans Enforcer police car. This firms up the ride and makes a quantum leap in handling.
This What If? Pontiac's interior modifications are in line with previous X-400 show cars, but with a '70s-style interpretation. The cabin features four bucket seats, finished in a Firethorn Red glove leather with horizontal pleats. The stock dash enjoys an engine-turned applique and a full complement of gauges, including a tachometer and boost monitors. CB radio? Of course, and it would be built into the full-length console, which runs up and between the rear seat backs. The console features the same engine-turned applique for the top surfaces and matching leather for the sides, and houses a Hurst DualGate shifter and a matching handle for the electric-operated dual-exhaust cutouts.
The rest of the '76 X-400's visual package fits in the context of the era, too. The colors reflect the tastes of the '70s, but do not venture into the excessively gaudy territory the decade was known for. Anyone who suffered through the leisure-suit era will understand the concern.
Pontiac designers were very much taken with Firethorn Red, a metallic burgundy more on the reddish side. Proving that less is more, we forego the garish two-tone paint scheme for this bright monochromatic look. Finished off with a set of Honeycomb wheels and fat radial tires, we have the look that fits the era and stays true to what made the X-400s so special.
This car, like many of the others featured in What If?, is something that could be replicated by a Pontiac hobbyist looking to make a unique visual statement with a '76 Grand Prix. We hope this one comes to life, especially with a turbocharged Super Duty 455!
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