For 1989, Pontiac added a couple of engines to the GP
lineup. As a midyear introduction, a stroked 3.1-liter version of the 2.8 V6 was
implemented, but coupled only to an automatic. The larger engine developed 140 hp at 4800
rpm, with 180 lbs.-ft. of torque at 3600.
Also available only with an automatic transmission was
the Grand Prix Turbo, which actually was not just an engine
option, but a limited-production car that could truly be called the first high-performance
Grand Prix since the demise of the 455 SJs. It differed from lesser models in quite a few
The engine was developed by ASC/ McLaren for use
exclusively on this car. While the block and bottom end were the same as the normally
aspirated versions, they were "hardened selected castings" with more rigid quality-control
standards than normal. The turbocharger was the Garrett T25 model. The water-cooled turbo
blew into an air-to-air intercooler on its way to the multi-point fuel-injection system.
The modifications were good for a very respectable 205
hp at 5200 rpm, with 225 lbs.-ft. of torque at 2400. Maximum torque was actually governed
by the computer to avoid overloading the beefed-up automatic transaxle. ABS was standard a
The body received revised front and rear fascia panels,
as well as larger side skirts to accommodate the 245/50ZR-16 Goodyear Eagle Gatorback
radials, which were mounted on gold cross-lace 16x8-inch wheels.
The exterior revisions definitely gave the GP Turbo an
aggressive and distinctive look, which it could back up.
Zero-to-60 times were in the low 7-second range, with quarter-mile times in the mid-15s at
around 90 mph.