The 1987 was the last of the Buick Grand Nationals. Only 547 were produced making then quite rare and very collectible The GNX was built as a limited edition by both Buick and ASC/McLaren. Buick delivered fully optioned Grand Nationals over to ASC/McLaren. Specialty Products to be modified extensively.
Modifications started with the engine which received special components, including more efficient Garrett air-to-air intercooler. The pipe that make the intercooler to the engine is specially coated with a CERMATEL (ceramic/aluminum) coating for increased heat rejection and dissipation which is the key to increased turbocharged engine performance! For additional heat dissipation, front fender vents were installed to pull the heat away from the engine while driving.
The engine also received a special Garrett "hybrid" T-s turbocharger that uses a very lightweight ceramic impeller (as opposed to metal for the GN). The decreased weight allows the turbocharger to spin up much faster, thereby decreasing the turbo-lag time inherent in turbocharged engines. For additional efficiency the turbocharger incorporates special low drag, dynamic turbine shat seals, and a built in contamination trap. The system uses an electronic wastegate, and maximum boost is set at 15 psi.
The net result of these modifications was an engine that produced well over 275 horsepower and a fantastic (by today's production car standards) 360 ft. lbs. of torque. No other production V-6 engine that Buick has produced to date, including the new Series II Supercharged engine can touch this powerplant in brute power in original factory configuration.
To handle this extra power, the transmission was beefed up with firmer shifts and the rear axle received a longitudinal torque ladder bar with a panhard rod to help wheel hop and torque twist. Likewise, it received a special rear axle housing cover (aluminum, with GNX embossed on it) that serves as an additional strengthening element and point for the torque bar. For even more strengthening, the car body received special structural reinforcements in the form of "behind-the-back-seat bracing" and special chassis (steel cross member between the chassis rails) bracing.
The GNX was the only Regal to ever receive 16 in. wheels. The front and rear wheels were not interchangeable as they were smaller in front, thus receiving smaller front tires (P245/50VR16 front and P255/50VR16 rear).
Special (welded-in) fender flair's were added to the wheel openings to make more room for the oversized wheels and tires. The wheels themselves are a lightweight alloy, which together with special aluminum bumpers and brackets and other weight saving measures, make the GNX the quiet nimble and very responsive.
The engine is monitored by a special Steward Warner analog gauge package that includes a 16o m.p.h. speedometer, 8000 r.p.m. tachometer, oil pressure gauge, water temperature gauge, fuel gauge, and turbo boost gauge with a 15 p.s.i. limit.
All GNX's were black in color and received only minor exterior identification in the form of "GNX" badges placed on the front radiator grille and rear deck lid. Additionally, a special turbocharger heat shield had "GNX" stamped-out on large letters. Plus, the aluminum rear axle cover was embossed with the same "GNX" lettering. Each GNX recited a special numbered plaque mounted on the passenger side dash which identified the number of that particular car (1-547). Also the Fischer Body Plate has the name "GNX" stamped on it! Special decals that include the "GNX" lettering were use on the intercooler and other locations. All GNX's have hidden I.D. stampings to prevent fakes. To order a (GNX exclusive) part you must supply the V.I.N. number, the turbocharger number and other I.D. numbers. This is to stop people from ordering parts simply to horde them and perhaps more importantly, to stop fakes from being produced using factory original parts.
Info from the Buick Regal Super Facts and Figures Book
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