Boosted: New Blower Adds 20 hp to GTPThe 3800 Series II V6 in the 2004 Grand Prix is wholly unchanged, but the supercharged version in the GTP model jumps from 240 to 260 horsepower. This is due, largely, to a new-generation blower.
It's still an Eaton-supplied Roots-type compressor, but this fifth-generation supercharger for the '04 GTP is significantly more efficient. (The blower in the '97-03 cars was a third-generation design.) The new supercharger's biggest advantages include a larger, less-restrictive outlet port and easier-to-spin rotors.
The larger outlet permits more air to flow into the cylinder heads, while the freer-spinning rotors require 13 percent less power to turn-this means horsepower otherwise used to turn the rotors is freed up to get to the drive wheels.
Part of the rotors' decrease in friction comes from a new powdercoating, which replaces a previous epoxy coating on the Third-Gen. rotors.
Finally, the supercharged 3800 engine is now tuned to run on regular, 87-octane fuel.
| 2003 Grand Prix GTP vs. 2004 Grand Prix GTP |
| | 2003 GTP | 2004 GTP |
| EXTERIOR DIMENSIONS |
| Wheelbase | 110.5 in. | 110.5 in. |
| Overall length | 197.5 in. | 198.2 in. |
| Overall width | 72.7 in. | 71.6 in. |
| Overall height | 54.7 in. | 55.9 in. |
| INTERIOR DIMENSIONS |
| Head room (front) | 38.3 in | 38.8 in. |
| Leg room (front) | 42.4 in. | 42.2 in. |
| Shoulder room (front) | 58.5 in. | 58.9 in. |
| EPA interior volume | 115 cu. ft. | 114 cu. ft. |
| Cargo capacity | 16 cu. ft. | 16 cu. ft. |
| POWERTRAIN |
| Engine | 3.8-liter V6 | 3.8-liter V6 |
| Fuel delivery | Sequential fuel inj. | Sequential fuel inj. |
| Power adder | Supercharger | Supercharger |
| Horsepower | 240 @ 5,200 rpm | 260 @ 5,200 rpm |
| Torque (lbs.-ft.) | 280 @ 3,600 rpm | 280 @ 3,600 rpm |
| Transmission | 4-speed auto. | 4-speed auto. |
| | | TAPshift manual control* |
| SUSPENSION & CHASSIS |
| Front | MacPherson strut | MacPherson strut |
| | with coil springs, | with coil springs, |
| | 20mm hollow | 20mm solid |
| | stabilizer bar | stabilizer bar |
| Rear | Independent, tri-link | Independent tri-link |
| | with coil-over strut, | with coil-over strut, |
| | 18mm stabilizer bar | 17.2 mm stabilizer bar |
| | | (19.4 mm stabilizer bar)* |
| Steering ratio | 15:1 | 13.2:1 |
| Brakes (front) | 10.95-in. vented disc | 11.7-in. vented disc |
| Brakes (rear) | 10.6-in disc | 10.5 disc |
| ABS | Standard | Standard |
| WHEELS & TIRES |
| Wheels | 16-in. cast aluminum | 17-in. cast aluminum |
| Tires | P225/60R16 | P225/55R17 (H rating) |
| | | P225/55R17 (V rating)* |
| * Included with Competition Group. |