The 1987 Buick Grand National coupe uses a turbocharged 3.8-liter V-6 engine codenamed the LC2 that produces 245 peak horsepower and 355 foot-pounds of torque. A more powerful version of the engine is used in the limited production Grand National GNX that is tuned to produce 300 horsepower and 420 foot-pounds of torque and is powerful enough to accelerate the 3,500-pound Buick from 0 to 60 in 6 seconds.
The standard Buick Grand National LC2 engine is based on the Buick LD5 "Fireball" 231 family of V-6 designs and uses several additional technologies to maximize its forced-induction power gains over its naturally aspirated ancestor. A Garret air intercooler, wasted spark ignition and sequential fuel injection are standard on the 1987 version of the engine. The LC2 became standard on the Grand National in 1984, though the engine only produced 200 horsepower in those models. The upgraded LC2 engine used in the Grand National GNX was a stock LC2 engine tuned by the McLaren British car engineering company known for its racing heritage in Formula One. Modifications to the GNX LC2 included a ceramic turbocharger, improved intercooler, modifications to the engine's management software, and a dual exhaust system to improve airflow to the engine.