Summary

Powered by a turbocharged V6 engine mated to a 4-speed automatic transmission; #78 out of 547 built. Shows only 4,620 miles on the odometer (with 4,589 miles indicated as actual miles on the title).

Details

This GNX is #78 out of 547 built and shows only 4,620 miles on the odometer (with 4,589 miles indicated as actual miles on the title). This GNX was delivered to Tarzy Buick, Inc., in East Brunswick, NJ, on June 10, 1987. This exceptional GNX has been in a private collection since 2010. A total of 547 Grand Nationals were sent to ASC/McLaren for extensive modifications inside and out. These included performance upgrades to amplify the potency of the engine even further, as well as several suspension, interior and exterior upgrades. The GNX was officially advertised at 276hp and 360 ft/lbs of torque, but these numbers were soon found to be understated. Third-party testing revealed that the GNX's turbo V6 actually produced more than 300hp and 400 ft/lbs of torque at 3,900 rpm. This allowed the GNX to outrun contemporary models from Ferrari and Porsche and made it one of the fastest production cars at the time. This car features a new Garrett Hybrid turbo with a super-lightweight ceramic impeller. The maximum boost is set to 15 psi; there are special dynamic turbine shaft seals to reduce drag on the impeller shaft. The redesigned turbine housing included a contamination trap to keep solid particles from damaging the turbo internals. There's also a more efficient Garrett air-to-air intercooler with higher fin count for additional cooling capacity, as well as a specially coated intercooler-to-engine pipe for a cooler and denser charge of air. The car also has a beefed-up TH2004R transmission, special front-mounted auxiliary oil cooler, special turbocharger heat shield with exclusive 'GNX' stamped design and recalibrated Engine Control Module (ECM) specifically for the GNX. There is a better-flowing dual exhaust with low-restriction mufflers, also designed to clear the new suspension components. Handling the added power is a GNX-embossed, beefed-up housing that not only provides additional rear axle rigidity, but a solid mount for the longitudinal torque ladder bar that reaches forward and mounts to specially reinforced bracing just behind the rear seat. The result is a component that is very effective in planting the rear tires and applying full power to the ground during a launch. Also included is a Panhard rod and track rod to keep the axle located in place when cornering. The standard Buick slide-rule speedometer and warning lights were replaced with a full complement of Stewart Warner gauges that includes a 160-mph speedometer, 8,000-rpm tachometer, turbo-boost gauge, oil pressure gauge, fuel level gauge and water temperature gauges. The seats were standard-issue Grand National type, but the interior was accented with special GNX emblems and finished off with a special numbered plaque mounted on the passenger side of the dash.