The 1987 Buick Regal Grand National remains one of the most talked-about American performance cars of the 1980s, and its factory-built GNX variant pushed the platform even further. Built through a collaboration between General Motors and ASC McLaren, the GNX was designed to extract every last bit of speed from Buick’s turbocharged 3.8-liter V6. Decades later, the question of just how fast these cars were, and how much faster aftermarket forced-induction setups can make them, continues to drive intense interest among collectors and drag-strip regulars alike.
That ongoing fascination is tied to more than just nostalgia. The Grand National and GNX emerged at a time when emissions regulations and fuel-economy concerns had tamped down the wild horsepower figures of the muscle-car era. Against that backdrop, a blacked-out Buick coupe that could out-sprint many contemporary V8s felt like a revelation. Understanding how the factory cars performed, and how far enthusiasts have tried to push them with turbo and supercharger swaps, helps explain why their acceleration numbers are still debated and celebrated today.
What the Stock Grand National Actually Ran
Before measuring the impact of any supercharger or upgraded turbo setup, the baseline matters. Instrumented testing on a 1987 Buick Regal Grand National produced 0–60 and quarter-mile results that were startling for a mid-size Buick coupe of that era. The car’s turbocharged V6 made it competitive with, and in some cases faster than, V8-powered muscle cars and even certain European sports cars that cost two or three times as much. Those published figures, which included trap speed data and documented test conditions, gave the Grand National a reputation that far exceeded what its conservative exterior suggested.
The Grand National’s performance came from a combination of turbo boost, rear-wheel drive, and a relatively light curb weight for a body-on-frame GM G-body. That package meant strong launches off the line and consistent quarter-mile passes when traction was available. Period reviews noted that the car’s acceleration felt deceptively violent given its subdued, all-black styling, and that its mid-range surge was particularly impressive once the turbo was fully spooled. For a vehicle that shared its basic underpinnings with the Buick Regal and Oldsmobile Cutlass, the Grand National’s straight-line speed was an anomaly that General Motors ultimately chose to highlight rather than hide.
The GNX: GM and ASC McLaren’s Factory Hot Rod
The GNX took the Grand National formula and turned it up. General Motors recognized the GNX as an official program vehicle, and the GM heritage listing for the 1987 Buick Regal GNX identifies it as a documented part of the company’s performance history. That corporate acknowledgment separates the GNX from the dozens of aftermarket-modified Grand Nationals that followed. This was not a backyard build or a dealer-installed option package; it was a coordinated effort between GM and an outside engineering firm to create the fastest possible version of the platform before the G-body was discontinued.
ASC McLaren handled the conversion work. Original dealer brochures, order forms, and pricing sheets preserved in the ASC McLaren archive detail what was changed compared to a standard Grand National and how the car was marketed to buyers. The modifications went beyond a simple boost increase. ASC McLaren’s program addressed the turbocharger hardware, intercooler layout, exhaust flow, and suspension tuning, creating a car that was meaningfully different from the base Grand National in both straight-line speed and overall driving character. The limited production run, combined with the factory-backed engineering and documentation, is what separates the GNX from the broader Grand National lineup in the eyes of collectors and performance historians.
Supercharged Versus Turbocharged: A Common Misconception
The headline question, how fast is a supercharged Buick Grand National, contains a wrinkle that most casual enthusiasts miss. The factory Grand National and GNX were turbocharged, not supercharged. A turbocharger uses exhaust gases to spin a compressor that forces more air into the engine, while a supercharger is belt-driven off the crankshaft. Both are forms of forced induction, but they deliver power differently in terms of response and power curve. The turbo setup on the Buick 3.8-liter V6 was central to the car’s identity, and most period testing, including the instrumented results recorded for the 1987 Grand National, reflected the factory turbo configuration rather than any belt-driven blower conversion.
That said, aftermarket supercharger conversions for the Grand National platform do exist in the enthusiast community. Builders have experimented with centrifugal and positive-displacement superchargers as alternatives to the original turbo, often as part of complete engine builds that change compression ratio, fueling, and engine management. The appeal is instant throttle response without the lag that turbochargers can produce at low RPM, along with the visual novelty of a blower under the hood of a car traditionally associated with turbo power. However, verified instrumented data from supercharged Grand National builds is scarce. Most acceleration claims for these conversions come from enthusiast forums, personal websites, and informal dragstrip reports rather than from standardized track tests with disclosed conditions.
This gap in verified data is worth acknowledging directly. The aftermarket world moves fast, and individual builds can vary wildly in power output depending on supporting modifications like fuel system upgrades, intercooler design, transmission work, rear-axle gearing, and tire choice. Claiming a specific 0–60 or quarter-mile time for “a supercharged Grand National” without specifying the exact build, test conditions, and measurement method would be misleading. The factory turbo numbers, by contrast, were recorded under controlled conditions and remain the most reliable benchmark for the platform’s performance ceiling in stock or near-stock form. When enthusiasts quote times for heavily modified or supercharged cars, those figures are best understood as snapshots of individual projects rather than definitive standards for the entire Grand National community.
Why the Numbers Still Matter Decades Later
The Grand National and GNX occupy a unique position in American car culture because their performance numbers were so far ahead of what buyers expected from a Buick in the late 1980s. At a time when many domestic performance cars were struggling to produce adequate horsepower under tightening emissions regulations, the turbocharged V6 in the Grand National delivered acceleration that embarrassed cars with twice the displacement. The GNX, with its ASC McLaren upgrades and factory endorsement, pushed the envelope even further and became the send-off for the G-body platform. The contrast between the cars’ anonymous, boxy styling and their real-world speed helped cement their legend.
Collector interest has followed accordingly. The GNX in particular commands strong prices at auction, driven in part by its limited production and its status as a GM-authenticated performance vehicle. The original program paperwork preserved by ASC McLaren, including dealer brochures and order forms, has become collectible in its own right because it documents exactly how the cars were specified and sold. For many buyers, having proof that a car retains its factory turbo configuration, or that it is an authentic GNX rather than a clone, is more important than any claimed modification or dyno number. In that sense, the verified acceleration figures from period testing and corporate archives do more than settle bench-racing arguments, they help define what these cars are and why they matter.
Framing the “How Fast” Question Today
When someone asks how fast a supercharged Buick Grand National is, the most accurate answer starts with a clarification: in factory form, these cars were turbocharged, and their performance is best understood through documented tests of stock or lightly modified examples. The GNX adds another layer, standing as the ultimate factory-backed expression of the platform. Any supercharged variant is, by definition, an aftermarket reinterpretation that can range from mild to extreme. Without standardized, repeatable testing, it is impossible to assign a single, authoritative acceleration figure to such a broad and loosely defined category of builds.
What can be said with confidence is that the foundation provided by the 3.8-liter V6, rear-wheel-drive layout, and relatively low curb weight gives tuners plenty of room to explore both turbo and supercharger setups. Some owners prioritize period-correct restorations that preserve the original turbo hardware and factory feel; others chase ever-quicker elapsed times with modern forced-induction technology. In both cases, the legend of the Grand National and GNX is anchored in the same core reality: these cars shocked the industry with their speed when new, and the debate over just how fast they can be made—whether turbocharged or supercharged—continues to fuel their appeal decades later.
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*This article was researched with the help of AI, with human editors creating the final content.
