26/07/2026
TRACO Engineering used stock pistons. Stock connecting rods. A stock crankshaft. A stock oil pan. A stock camshaft. Stock pushrods. They won the 1968 and 1969 SCCA Trans-Am Championships with Mark Donohue driving Roger Penske's Sunoco Camaro Z/28, and the engines that powered those championship cars used a surprising number of off-the-shelf Chevrolet parts. TRACO, founded by racers Frank Travers and Frank C**n in Culver City, California, didn't win Trans-Am by building exotic hardware. They won by assembling common hardware with uncommon precision. The difference between a 290-HP factory DZ 302 and a 440-HP TRACO 302 wasn't the parts list. It was the hands that assembled them.
TRACO's dynoed output tells the real story. Gordon Chance, TRACO's engine builder, reported that their Trans-Am engines made 400 to 405 HP at 6,800 to 7,000 RPM with a single four-barrel carburetor. With the Cross-Ram dual four-barrel intake manifold, output climbed to approximately 440 HP at 7,200 RPM. Billy Howell, the Chevrolet factory engineer assigned to the Penske Trans-Am program and the carburetor tuner for Donohue's car, confirmed the numbers: a really good single four-barrel engine made about 425 HP. The Cross-Rams made about 450 HP. Those old iron cylinder heads were completely maxed out at those power levels. The connecting rods limited the engines to a maximum of 6,800 to 7,000 RPM, and over-revving was a constant problem for drivers who weren't as disciplined as Donohue.
The Cross-Ram intake manifold was the critical piece. Homologated for SCCA competition in December 1967, the Cross-Ram used equal-length runners that crossed over the top of the engine, feeding each cylinder bank from the opposite side's carburetor. This cross-feeding arrangement equalized intake runner lengths, improving volumetric efficiency at high RPM and providing approximately 25 additional horsepower over the single four-barrel setup. Donohue himself wrote that the Cross-Ram "was so much faster than the single four-barrel that we reckoned it was another Unfair Advantage." The Cross-Ram used dual Holley four-barrels with a cowl-induction plenum that drew cool, high-pressure air from the base of the windshield. On the street, the Cross-Ram was nearly undriveable: no manifold heat crossovers, no chokes, terrible cold-start behavior. On the track, it was the difference between winning and losing.
The TRACO approach to Trans-Am was assembly-line discipline applied to race-engine preparation. Between every race, Penske's team tore the car down to the bare tub. The tub was steam-cleaned and repainted inside and out, including underneath. The engine was shipped back to TRACO in Culver City. The suspension was magnafluxed. The rear axle was swapped for a fresh unit. All spindles, hubs, bearings, and steering knuckles were replaced with new parts. Brake discs and pads were replaced. All fluid systems were flushed. A fresh engine went in. The transmission was replaced every two or three races. This level of preparation was what Donohue meant when he titled his autobiography "The Unfair Advantage." The parts were the same as everyone else's. The preparation was not. TRACO won Trans-Am with stock Chevy parts assembled with a level of care that nobody else was willing to match.
