The Firebird FireFox and FireFox II

[BadAzzGTA89]

The Firebird FireFox and FireFox II





Factory experimentals. They can be defined as one off engineering exercises designed to push the envelope. Pontiac has been at this for decades and it continued into the twilight years of the third generation platform. In the years preceding the
introduction of the 1989 Turbo Trans Am, Pontiac was busy building excitement. Some of the exercises included a 3.8 liter high output Turbo Trans Am that delivered 360 hp and 412 lbs of torque. The 3.8 liter HO drivetrain consisted of a ZF six speed and a Dana 44 rear with 3.92 gears. Pontiac also examined twin turbo charging with a 5.7 liter red and black Trans Am equipped with a set of Garrett T-3 turbos. This 5.7 liter was fed by 16 fuel injectors, three GNX fuel pumps, two air meters and two GNX intercoolers. The driveline pieces were the same ZF six speed spinning 3.73 gears. The twin turbo put out 605 hp and 700 lbs of torque. It was among these factory super cars from Pontiac that the original Firefox was born. This sinister 5.7 liter black GTA came with the the ZF six speed and heavy duty Dana rear end as well as suspension modifications. It was the ultimate GTA and the impetus for another tire scorching Firefox three years later.

[BadAzzGTA89]

Continued.....................


The Firefox II, based on a 1991 Trans Am was built by Ponitac in conjunction with TDM Technologies. TDM is an automotive engineering support firm based in Livonia, Michigan. This incarnation of the original Firefox differs from the original in several areas. The Firefox was powered by a beefed up Tuned Port Injected 5.7 liter with aluminum heads and a bumped up compression ratio of 10.5:1. The Firefox was also given several tried and true TPI modifications. Airflow into the TPI engine was aided by porting the runners from 1.375 to 1.750 inches in diameter while fuel injector flow rates were increased. Rounding out the engine modifications were roller tip rocker arms and specific valve timing. The restrictive stock exhaust manifolds were removed and a set of Edelbrock headers were installed to remove the spent gases. The Firefox had provisions for a catalytic convertor but this prototype was not so equipped. Horsepower levels were an impressive 328 hp at 4500 rpm and a stump pulling 395 lbs of torque at 3500 rpm. It is needless to say that these levels of performance would decimate stock driveline pieces. As was the case with the original Firefox, the shifting duties were handled by a Corvette ZF six speed tranny with power being channeled to a limited slip rear with 3.91 gears. Residing in the rear of Firefox II is a suspension that F-body owners have wanted for the last 10 years, an independent rear suspension. This all aluminum independent rear suspension required the fuel tank to be removed and replaced with a small fuel cell fitted in the luggage compartment. It also required a compact muffler mounted snuggly behind the IRS assembly. The IRS was apparently considered for the 1989 20th Anniversary Turbo Trans Am and the original Firefox but has never made it on a production F-body due to cost and complexity. The rolling stock was also upgrade to handle the increased performance. The Firefox II rode on sticky 275/40/17 Goodyear Eagle ZR40's and 17 inch BBS 3 piece rims with a honeycomb design similar to the GTA's stock WS6 rims.

The Firefox II's performance times were quite impressive and it could be considered the ultimate third generation Trans Am ever. 0-60 times were 5.2 seconds with the quarter mile time coming in at 13.5 seconds at 103.2 mph. The IRS equipped Firefox delivered skid pad times of .93 g while racing through the slalom at 67.0mph. According to Motor Trend, these times were slightly off the mark of a 1991 ZR-1 at 68.6 mph These times put the the Firefox in LS1 Corvette, SS, Firehawk, and Cobra territory.

[BadAzzGTA89]

In retrospect, the legacy the original Firefox and Firefox II left were that the lessons Pontiac learned from these cars undoubtedly made there way into the fourth generation Formula's and Trans Am's. It also showed that TPI 5.0 and 5.7 liter cars could be modified to deliver awesome levels of performance and power. In the end, these are the purposes of factory experimental cars, to bring innovations to new models and show enthusiasts where the envelope lies so we can get there and even surpass it.

1991 Firebird FireFox II Specifications:

Engine..........................350 (5.7L)
Horsepower..................328@4500
Torque.........................395@4500
Compression.......................10.5:1
Transmission......ZF 6 Speed Man.
Axle Ratio..............................3.91
Weight..................................3477
0-60..........................................5.2
1/4 Mile..............*13.5@103.5mph
Braking...............................135 Ft
Skidpad...................................93g

*Motor Trend 12-91

[BadAzzGTA89]

Here is the car.............

[Al]

Originally posted by BadAzzGTA89
According to Motor Trend, these times were slightly off the mark of a 1991 ZR-1...

Close one, you scared me. (this is obvious by now)