1984-1987 Buick Grand National or '87 GNX - Hunting for Rare or Unicorn

The 3.8L turbocharged V6 engine that powered the Grand National and GNX was a unique creation in an era still recovering from the muscle car collapse. Unlike most performance cars of the time, it didn’t rely on a big V8. Instead, Buick engineered a torquey, boost-happy V6 that could blow the doors off cars with twice the displacement (1987 GNX #51 produced of 547 built - lead photo).

The Basics:

• Displacement: 3.8L (231 cu in)
• Iron block, iron heads (heavy but durable)
• Sequential fuel injection
• Computer-controlled ignition
• Single Garrett T3 turbocharger
• Optional air-to-air intercooler (added in 1986+)

Above: 1984 Buick Grand National 3.8L V6 turbocharged engine

Evolution Over the Years:

Above: 1984 Buick Grand National interior

What Made It Special:

• Torque monster: Peak torque at just 2,400 rpm made it feel instant.
• Turbo lag? Minimal by mid-'80s standards thanks to tuning and torque curve.
• Overbuilt: Thick block and rotating assembly could handle big boost, which is why so many GNX clones are pushing 500+ hp today with stock internals.
• Underrated output: Buick purposely downplayed horsepower figures so it didn’t overshadow the Corvette. But dynos don’t lie.

Part 2: The GNX & ASC/McLaren Engineering Partnership

Above: 1987 GNX (photo courtesy of Motor Authority)

“Goes Like Hell” — And Handles Too

The GNX (Grand National Experimental) was more than just a faster Grand National. It was a covert skunkworks project between Buick and ASC/McLaren (yes, that McLaren, though a separate U.S. division at the time).

Above: 1987 GNX undercarriage shows the improved suspension geometry for better traction and reduced wheel hop. Also shown is the limited slip differential that's unique to the '87 GNX.

ASC/McLaren’s Role:

• Reinvented the suspension geometry for better traction and reduced wheel hop
• Installed a unique torque arm rear suspension and Panhard bar
• Upgraded to 16” aluminum mesh wheels wrapped in Goodyear Gatorbacks
• Revised Garrett T3 turbocharger with ceramic impeller for faster spool
• Custom low-restriction exhaust system
• Added intercooler with improved airflow
• Tuned the transmission and reprogrammed the ECU for quicker shifts

Above: Garrett T3 turbocharger with ceramic impeller for faster spool up - equals less turbo lag

Fun Engineering Facts:

• Rear suspension eliminated the notorious G-body "hop and squat"
• 1/4-mile testing was done with engineers intentionally sandbagging to avoid embarrassing the Corvette
• The GNX had functional fender vents to reduce under hood temps
• All GNX units were shipped from GM to ASC for conversion, then delivered to dealers

Part 3: Collector’s Guide to the Grand National and GNX

Is It Time to Buy? Well… It Depends.

Prices have gone up big time over the past decade, especially for clean, original examples. Here's what to know if you're looking to get in the game.

What to Look For:

Above: The window sticker for a 1987 GNX with 16 miles showing on the odometer

Paperwork:

• Matching VINs
• Original build sheets or window stickers
• GM documentation (SPID label in trunk is critical)

Above: 1987 GNX SPID label - On a 1987 Buick GNX, the SPID (Service Parts Identification) label, which also contains RPO (Regular Production Options) codes, is usually located on the trunk lid (decklid). Some GN's also have the SPID label inside the glove box or on the driver's side door jamb. 

Visuals:

• Factory paint (GM code “19U” for Grand National black)
• Interior trim codes (often gray with Lear-Siegler buckets)
• Original gauge cluster (GNX has Stewart-Warner analog dials)
• GNX # plate on dash (547 made, individually numbered)

Above: Number 227 of the 547 1987 GNX vehicles built

Mechanical:

• Turbo and intercooler integrity
• Transmission (200-4R) – check for firm shifts, no slipping
• Rear end condition (GNX had special differential)
• Watch for modded-to-death examples—originality = $$$

What They’re Worth (as of 2025):

Note: Modded GNXs with undocumented changes may go for less, but originality is everything to collectors.

Above: 1987 Buick Grand National (some photos courtesy of Mecum Auctions)

Tips Before Buying:

• Join GN forums like TurboBuick.com or V8Buick.com for community insights
• Ask for cold start videos if buying remotely—turbo V6 issues usually show up cold
• Inspect rear frame rails for rust—G-bodies are prone to rot
• Buy the best one you can afford. Restorations are expensive and parts are drying up.

Final Thoughts

The Grand National and GNX weren’t just fast—they were proof that Buick had the engineering chops to beat the best. The turbo V6, ASC/McLaren tuning, and sleeper styling made these cars instant legends. Today, they’re not only fast classics but smart investments—as long as you buy wisely.

Classic Industries - a Great Source for GN and GNX Parts

Above: 1987 GNX engine bay

It doesn't matter whether you're on the hunt for a Buick Grand National or you're on a glorious expedition for the rare Buick GNX, Classic Industries offers an abundance of components for GNX and Grand National gearheads. You can request a Buick Regal Parts and Accessories Catalog for free. You can also search for Grand National or GNX components on the Classic Industries Buick Regal shopping page and the other sub models online: Limited, T-Type, Turbo T, and Sport.

Classic Industries Archives of Buick Regal: Grand National, GNX, Limited, T-Type, Turbo T, and Sport Articles

But wait, there's more - There's a growing library about the Buick Regal and the various sub models: Grand National, Limited, T-Type, Turbo T, Sport, and GNX - for your entertainment, education, inspiration, and information. Have fun in the CI library!

• Buick Regal T-Type & Turbo T: The Grand National's Turbo Siblings
• 1985 Buick Regal - A Tribute to Mom
• 1981 Regal Pace Car - The GN's Precursor
• Roadster Shop's 1,600 Horsepower Buick Grand National
• 1987 Buick Grand National - The Dark Side
• Ringbrothers INVADR: The Ultimate Buick Grand National Resto-Mod?
• An American Legend: Throttle House's Retro Review of the Buick GNX
• Mint '87 Buick GNX Sold for $200,000
• A Story of Style Over Speed - 1973-1987 Buick Regal - at First
• Essential Buick Regal Parts Catalog: 1973-1987 Restoration Guide

Above: 1987 Buick Grand National rear (same vehicle as the side view photo above - backdrop gives you the clue). An '87 Grand National may well be a great compromise to finding and buying the unicorn '87 GNX. Since the Grand National for 1987 is less rare, you could purchase one for less money and not be as afraid to drive it.