This Hardtop/Cloth Turbo Trans AM Is One Of The Rarest GMS Ever

Pontiac emblems have adorned many fierce machines in homage to its warrior chief namesake, but few are as rare and fast as the '89 Turbo Trans Am. Owing to its limited production of only 1,555 vehicles and use of a turbo V-6 powertrain, the TTA promised to be a fitting celebration for the 20th Anniversary of the Trans Am, which it has since delivered on at every strip of pavement in the country. The use of Buick's 3.8L turbo V-6 in the body of the GTA managed to combine the best of both worlds for a lightweight, aerodynamic, powerful, and great-handling Pontiac.

Among the limited production of Anniversary T/As, 1,324 had Lexan T-tops and leather interiors. One hundred and eighty seven were ordered with T-tops and a cloth interior, and only 24 hardtops had leather.

But for the ultimate in speed, exclusivity, and light weight, there was an "optionless" model. This TTA featured a hardtop and a cloth interior. Marv Spomer was lucky enough to snatch one up at an auto auction in Minneapolis, back in the spring of 1990. As an owner of a Pontiac/GMC dealership, Marv would frequent the auctions looking for a good deal on something to sell on his lot. "A bunch of TTAs starting coming through--all pace cars--and I bought and sold a couple of them. When I was driving the first one I thought it would be a fun car to own, but I didn't want the hatch roof." When a hardtop TTA came through the auction with only 89 miles on it, he wasted no time in snatching it up. "Later I found out that this was a (GM) central office car that was found at Indianapolis when they opened the garage, and was probably never even used since it didn't have the removable top. The car still had the MSO and had never been titled or retail-sold," Marv said. Having taken it to a few car shows, the TTA has since acquired a few miles, now around 4,100, but given its rarity, Marv prefers to now park it inside the showroom of his new classic-car dealership. While exact figures cannot be verified, most sources maintain that either 13 or 15 base models were manufactured by GM in partnership with Performance Automotive Systems (PAS) in southern California.

Unlike their Canadian Fourth-Gen counterparts, F-bodies were made at that time at GM's Van Nuys, California, assembly plant. During the '89 model year white GTAs were picked at random, and instead of receiving a 350 V-8 and 700-R4 tranny, a 200-4R and turbocharged 3.8L from PAS were installed. PAS assembled the motors down the street at its 40,000-square-foot City of Industry, California plant with the same rigorous standards as the GNX. Except, unlike the turbo Buick motors, the TTA received a cross-drilled crank for better lubrication and a different set of heads as was required for proper clearance of the shock towers in the F-body. Reaching into the GM parts bin, PAS modified a set of transverse FWD 3.8L heads for improved combustion chamber design and exhaust flow. Subsequently a different set of pistons was required to maintain an 8.0:1 compression. To make the TTA especially potent, the larger GNX intercooler was added along with more boost (totaling 16.5psi).

Stainless steel 3-into-1 headers and exhaust along with a Bosch fuel pressure regulator and recalibrated ECM were also used by PAS to squeeze a little more juice out the 231-cube LC2. While these motors were rated at 250 flywheel horsepower to appease the Corvette crowd, in actuality, the TTA motor reportedly made 301 hp on the PAS engine dyno. This seems in line with chassis dyno testing, in which TTAs usually made around 220 ponies to the wheels. Torque was also reportedly 10 to 15 lb-ft higher than the advertised 340.With all that extra power it was decided that the TTA needed a better set of brakes to match. Again dipping into the GM parts bin, PAS pulled out the 1LE brake package originally engineered for Trans Am racecars. The kit included vented 12-inch front and 11.7-inch rear rotors to ensure fade-free performance. Meanwhile, the aluminum dual-piston front and single-piston rear calipers were borrowed from the Corvette.

The rest of the '89 Turbo Trans Am is nearly identical to the GTA in which it was based. Aluminum 16x8 wheels along with a good set of Goodyear rubber were standard equipment. The Australian Borg-Warner 9-bolt with a limited-slip differential and 3.27 gears, as well as the suspension, were also shared equipment with the GTA. However, unlike the portly GTA, the GN powertrain kept the TTA around 3,350 pounds. The superior weight distribution lent itself to increased handling, which in no way detracted from its impressive acceleration. Turbo T/As have been known to run the quarter in as fast as 13.4 seconds bone stock. That's pretty damn quick even today, but for 1989? What a rocket.

(Source : http://www.gmhightechperformance.com/features/0512gm_1989_pontiac_trans_am_turbo_feature/index.html)