Pontiac will be remembered for styling and shtick — Wide-Track, Ram Air, body cladding, screaming chickens. Behind the juvenile antics, though, there once existed a capable group of engineers. Pontiac Motor Division ran its own successful racing efforts, had its own chassis-tuning group, and fielded its own engines, including an overhead-cam in-line six and a V-8 family that was distinct from Chevrolet’s small-block. If that sounds redundant, ask Porsche executives how they’d feel about putting a Volkswagen four-cylinder in a 911. The sun was already setting on Pontiac’s golden age, however, when the engineers turned out their greatest effort: the Firebird Super Duty 455. The SD-455 has been accurately described as Pontiac’s last stand and the last real muscle car. It also prefaced the dawn of the performance era we enjoy today.
The Super Duty designation dates to Pontiac’s successful early 1960s efforts in NASCAR and the NHRA, but it lay dormant for almost a decade. By 1970, the division’s street machines, although wildly popular, had lost their performance edge to the likes of the Hemi-powered Plymouth Road Runner. At the same time, Pontiac had learned a great deal from running the Firebird in SCCA Trans-Am racing, including a novel concept called “handling.” A small engineering team led by Herb Adams, who’d fashioned the functional ground effects and heavy-duty suspension on the 19701/2 Trans Am, started work on a high-compression version of the division’s 400-cubic-inch V-8.
Corporate and geo-politics dampened those ambitions. The Israeli/Arab war of 1973 and the resulting OPEC oil embargo brusquely ended automakers’ horsepower war. A 1972 UAW strike at the Ohio factory that produced the Firebird and the Chevy Camaro crippled production such that General Motors considered discontinuing the pony cars altogether. Meanwhile, the men who’d shaped Pontiac’s performance image–general managers Bunkie Knudsen, Pete Estes, and John De Lorean, along with adman Jim Wangers–had all moved on, leaving the brand in the hands of corporate-minded executives who had no stomach for politically incorrect gas guzzlers.
But the engineering team was determined. They shifted their focus to a larger-displacement, 455-cubic-inch engine that could achieve their goals with a lower compression ratio. To avoid trouble with emissions tests, the engineers passed off their radical creation as a version of Pontiac’s high-volume, emissions-certified, lazy 455 big-block.
The SD-455 debuted quietly in 1973 as an option on the Formula and Trans Am versions of the Firebird. (A few Grand Ams and GTOs with the souped-up powerplant found their way into the hands of automotive journalists.) Its reported, likely made-up 310-hp rating easily embarrassed the 245-hp output of that year’s top Camaro and put the SD in league with the big-block dinosaurs that had ruled a few years before. But it was only the beginning. Adams and his team designed the engine to be an emissions-friendly starter kit, purposely packaging a mild camshaft and relatively restrictive exhaust manifolds with a heavily fortified block. It even had provisions for a dry-sump oil pump. Forged steel connecting rods, forged aluminum pistons, and modified cylinder heads rounded out an engine that begged for extensive modifications.
That was the case with the V-8 in the ’74 Trans Am SD-455 pictured here. Gregg Peterson ordered the car new as a present for himself upon graduating from the GM Institute. He’d played an active role in the development of his new ride — as a student he tuned the Trans Am for radial tires — and stayed on with Pontiac after college. As one might expect of a twenty-five-year-old with a fun job and the best-performing new American production car, Peterson was quite enthusiastic about his T/A.
“I had cops asking me if I wanted to spend a night in jail,” he says with a laugh.
He found safer channels for his passion at work. He wrote a letter to the head of Pontiac product planning urging that the division create a heavily modified test car for Car and Driver magazine. He wanted to revisit the infamous Pontiac versus Ferrari comparisons of the 1960s, only this time the target would be the mighty Daytona and its all-around performance.
“The objective was to create a Firebird capable of matching or beating a Ferrari Daytona: 165-plus-mph top speed, 0 to 60 mph in five seconds flat, 110-mph quarter-mile speed, 0.85 lateral g’s, excellent handling, and improved braking,” he says.
That’s exactly the sort of harebrained project that earned Pontiac street cred in the ’60s, but the climate had changed. The SD-455 squeaked out only a two-year, 1296-car production run before it was canceled. By the time interest in performance cars picked up again in the late ’70s, the Firebird was a 200-hp shell of its former self (although that was enough for Burt Reynolds).
Still, Peterson wanted a super Super Duty, and he was an able Pontiac engineer. The transformation started in 1980 with the suspension. He cut the stock springs, swapped in firmer aftermarket dampers, replaced the car’s rubber subframe bushings with thinner steel ones, and widened the wheels. The finishing touch was a beefy, oversteer-inducing rear antiroll bar that he’d created when developing the car for radial tires. Back then, it had been “a little too aggressive for management.”
Then there’s the 455 itself. Peterson produces a page-long list of “improvements,” including ported heads, a more aggressive camshaft, and a forged-steel crankshaft made for a 1963 NASCAR racing engine (a Smokey Yunick piece for which Peterson traded a 1966 Chevy Corvair Corsa). The upshot is a slightly less voluminous engine (433 cubic inches, due to a shorter stroke) that can rev to 6750 rpm and produce in the neighborhood of 390 hp.
The V-8 starts with a roar and settles into a deep yet raspy idle. The T/A lurches as Peterson shifts the fortified three-speed automatic into gear and drives to–where else?–a gas station. After pumping a few gallons of high-test, Peterson hands over the keys and helpfully advises me to keep the car pointed straight.
Like most heavily modified old cars — even an expertly done, 12,300-mile example — this Trans Am has its quirks. Sitting two inches lower than stock, it barely clears some bumps, nearly dragging the exhaust. I thus resist the urging of my adrenal glands and go for only two-thirds throttle. It’s enough. The engine roars up the tach before the transmission pulls off a head-jerking shift. The stock Trans Am was already one of the best-handling cars in its day; this one, with its well-considered adjustments, responds swiftly to the inputs to its racing-style steering wheel. We didn’t have a Ferrari along for a side-by-side test, but as an all-around performer that also feels raw and American, the truer and still-flattering comparison might be with a new Ford Mustang GT.
GM’s bean counters had the last word at Pontiac, gradually undermining the division’s independence and extinguishing its passion. Peterson left in 1987 — “it was untenable…the politics were awful” — and now works for Lotus. But his SD-455, a modern performance car as Pontiac engineers intended, lives on with its — and their — legacy untainted.
Engine: 7.5L V-8, 290-310 hp, 390-395 lb-ft
Transmissions: 4-speed manual, 3-speed automatic
Suspension, Front: Control arms, coil springs
Suspension, rear: Live axle, leaf springs
Brakes, F/R: Discs/drums
Weight: 3600 lb
Years produced: 1973-1974
Number produced: 1296
Original price: $4289/$4929 (Formula/Trans Am, 1974)
Value today: $30,000-$130,000 (Trans Ams are worth $20,000-$30,000 more than Formulas, even though the latter are much rarer. 1973 models are at least 50 percent more valuable than face-lifted ’74s.)
Why buy? There’s no shortage of second-generation Firebirds on the road, but very few have the pedigree or the performance of the SD-455. It combines the outrageous styling and copious power of earlier muscle cars with respectable handling. A pristine, original SD — verified with an X as the fifth character in the VIN — can sell for well into six figures. A contemporary Firebird with the more pedestrian 455-cubic-inch engine, on the other hand, tops out at about $35,000.