How Much Horsepower Does A Pontiac Grand Prix GTP Supercharged 3.8L Engine Have?

The Pontiac Grand Prix ranks as one of the most underappreciated Pontiac muscle cars of all time. Its longevity in the marketplace, posting eight generations spanning over 46 years, and the dominance of its GTO stablemate likely played roles in its lack of popularity. However, like fine wine, many feel the Grand Prix GTP got better with age with some calling the 1996 model, the last of the sixth generation, one of the coolest looking Pontiac models ever made.

One of the surprising facts about the Pontiac Grand Prix that not many people know is it has a long history in NASCAR being piloted by the likes of Dale Earnhardt, Richard Petty, Bobby Labonte, and Tony Stewart. While the seventh generation Pontiac Grand Prix took Labonte and Stewart to NASCAR championships in the early 2000s, it also welcomed General Motors supercharged 3.8-liter V6 as its powerplant.

The eighth and final generation of the Pontiac Grand Prix GTP combined the cool looks of the sixth generation and the seventh's supercharged 3.8-liter V6 and improved upon both. Those improvements make the Gen-VIII Grand Prix GTP an attractive and sporty option for one of the cheapest, most reliable Pontiac models you can still get today. 

[Featured image by IFCAR via Wikimedia Commons | Cropped and scaled | Public Domain]

Although the first installment of the supercharged 3.8-liter V6 in a Pontiac Grand Prix GTP didn't occur until 1997 to kick off the Gen-VII Grand Prix, the engine had been used in the Pontiac Bonneville for several years. An article from the pages of the October 1997 Hot Rod magazine, shared online by MotorTrend, reports the first supercharged 3.8-liter Grand Prix GTP had 240 horsepower at 5,200 rpm and 280 lb-ft of torque at 4,400 rpm. For comparison, the naturally aspirated 3.8-liter in a 1997 Camaro RS made 200 horsepower and 225 lb-ft of torque.

The Grand Prix GTP's Eaton supercharger played a significant role in providing the additional horsepower and torque. A naturally aspirated engine relies on vacuum to pull the mixture of fuel and air into the combustion chamber. However, a supercharger's forced air induction provides positive pressure, 7 psi in the 3.8-liter's case, eliminating the reliance on vacuum.

The Pontiac Grand Prix launched its eighth generation with the 2004 model year. In its review, Car and Driver reported the 2004 Pontiac Grand Prix GTP's supercharged 3.8-liter V6 horsepower increased to 260 and torque to 280 lb-ft. The increased power due to a bump from seven psi to 9.5-psi delivered by the twin-rotor Eaton supercharger.

The magazine recorded the 2004 Grand Prix GTP's zero to 60 mph acceleration at 6.6 seconds. It also posted a 15.0-second quarter mile sprint, crossing the finish line at 93 mph. While those numbers aren't too bad for a V6-powered four-door sedan with an EPA-estimated 27 mpg on the highway, Car and Driver only saw 17 mpg during testing. That's less than the EPA's projected 18 mpg in the city and a full four mpg under the 21-mpg combined estimate. One caveat to Car and Driver's "observed fuel economy" is the admission that its "staffers have heavier feet than most consumers."

[Featured image by IFCAR via Wikimedia Commons | Cropped and scaled | Public Domain]