Blue Oval Icons: The Boss 302 Brought Trans Am To The Street

Although the Mustang had ostensibly created the pony car segment in 1964, as that decade came to a close the competition was starting to come at Ford from all sides. And while high-performance development had largely focused on the drag strip, road racing had become increasingly popular as the ’60s progressed.

In 1966, the SCCA’s A and B-Production race classes had morphed into the now-legendary Trans-Am road racing series. Like the NHRA and other major racing series, the auto industry mantra of “Win on Sunday, sell on Monday” applied to Trans-Am as well, and the result was significant factory involvement in the series from almost every major domestic automaker, along with many foreign marques.

One of the first things I did on coming to Ford was straighten out the Boss 302. — Larry Shinoda, designer

Ford had made a significant mark on the B-Production series with the GT350R in the mid-1960s, taking no less than three championships with the Shelby-tuned machine. But if they were going to be contenders in Trans-Am they’d need a new production-based car packing even more firepower, as the series rules stipulated that each manufacture had to produce a certain number of road-going versions of the car they’d be campaigning for homologation purposes.

Like the Shelby GT350 before it, the Mustang Boss 302 was developed to homologate the car for SCCA road racing. The rulebook for Trans-Am was a bit less strict than B-Production though, making the Boss 302 a more street-friendly package than the uncompromising Shelby had been. (Photo Credit: Ford Motor Company)

The result was the Mustang Boss 302, a high-winding, corner carving machine that would become one of the most iconic and sought-after models from the muscle car era.

Development

While the Boss 302 was a comprehensive package that included significant chassis upgrades and a unique visual aesthetic, the centerpiece of the Boss 302 was its unique powerplant. After Chevrolet had out-muscled Ford in Trans-Am in 1968, it was clear that they would need more than a hopped-up Windsor small-block to get the job done. At the same time, development was underway at Ford for the Cleveland V8, which featured a new high-flow cylinder head design.

One of the key rules for Trans-Am at the time was the cap of 305 cubic inches of displacement and the use of a road-going version of the race engine in the homologation cars , so Ford developed a unique, high-revving 302-cubic-inch powerplant with stout internals that could handle the rigors of road racing. (Photo Credit: Ford Motor Company)

Seeking to merge the strongest assets of each design, Ford combined the Windsor block and Cleveland heads. Trans-Am homologation guidelines limited displacement to 305 cubic inches, so Ford developed a unique thin-wall, high-nickel-content, 302ci block casting and outfitted it with four-bolt mains, screw-in freeze plugs, and the canted valve design of the Cleveland cylinder heads, along with a unique high-lift camshaft, a forged crankshaft, an aluminum intake manifold, a Holley 780-cfm carb, and other go-fast goodies. The powerplant was given notoriously underrated official figures of 290 horsepower at 5,800 RPM and 290 lb-ft at 4,300 RPM.

Both a wide-ratio and close-ratio four-speed manual gearbox would be on offer, along with a roster of open and Traction-Lok differentials with gear ratios ranging from 3.50:1 to 4.30:1. To bolster the Mustang’s handling prowess, engineers outfit the Boss 302 with stiffer coil springs up front and heavy duty leaf springs in the rear, along with larger sway bars, reinforced shock towers, and upgraded spindles. Front disc brakes were standard.

In an interview with Consumer Guide, Boss 302 design head Larry Shinoda explained that the final product was actually significantly different than Ford’s original concept:

“One of the first things I did on coming to Ford was straighten out the Boss 302,” he explained. “They were going to call it the SR2. They had all this chrome on it. They were going to hang big cladding on the side, big rocker moldings. It was going to be more garish than the Mach 1.They had a big grille across the back, a great big gas cap, fake cast exhaust outlets, big hood pins and a really big side scoop. I took all that off, went to the C-stripe decal and painted out the hood, did the rear spoiler and the window shades and front air dam.”

Larry Shinoda’s revisions to the car helped to distill the Boss 302 down from the over-the-top treatment Ford had originally planned, giving it a stronger focus on track performance rather than eye candy. "I think it saved quite a few dollars when we counted it all up," he noted. "Don Petersen, who was in product planning at the time, got a big kick out of that. He said, "You trying to do our job for us?" I said, "No, just trying to do the job, period." (Photo Credit: Barrett-Jackson)

Larry’s revisions weren’t isolated to the aesthetics, either. “What they were working on was pretty much wrong,” he said. “They had an engine with high horsepower, but enormous ports, so the power was very, very peaky. They needed something with a much flatter torque curve. And they needed better vehicle dynamics. They were saying, “All it has to do is go fast.” I said, “That’s not really where it’s at. The Z-28 gets through corners well because it handles well. And it accelerates well off the corner because it got through the corner faster, so you think it’s got more horsepower than it does.”

Larry said he took some Ford folks in a company plane to fly over GM’s Proving Grounds. “I said, “See that? It’s Black Lake.” “What’s it for?” I said, “You’ll see.” Sure enough, here’s Roger Penske’s Trans-Am Camaro, the Sunoco Camaro, running on a skidpad. I said, “That’s what you need. You play with aerodynamics, suspension, roll stiffness, and tires, and you find out what’s going to get around there the fastest.” He quickly got an appropriation to repave Dearborn’s then-derelict test track.

Ford’s Trans-Am racing program was helmed by Bud Moore. After dialing in the setup during the 1969 season, two factory cars were campaigned for 1970, one of which would take home the championship with Parnelli Jones behind the wheel.

While Ford’s road racing effort had proven successful, both the SCCA and the auto industry on the whole were in a state of flux in the early 1970s, and the Boss 302 package would not return for 1971.

RoadRunner Revival

After a hiatus that lasted more than four decades, Ford revived the Boss 302 moniker for 2012. The package once again focused on enhancing the Mustang’s road course prowess, and like the original cars, the second generation Boss 302 was also motivated by a unique 302ci powerplant.

The second-generation Boss 302's unique sticker and aero package helped it visually stand out from garden-variety GTs. (Photo Credit: Ford Motor Company)

Internally known as the RoadRunner engine, under the hood of the late-model Boss 302 was a warmed-over version of Ford’s Coyote 5.0-liter V8 that featured a forged rotating assembly, revised camshafts, CNC-ported cylinder heads, and unique intake manifold design derived from Ford’s racing program. This combination was good for 444 horsepower and 380 lb-feet of torque. That power plant was mated to a six-speed MT-82 manual gearbox and sent the power to a limited-slip differential with 3.73:1 gears. A Torsen differential was also available.

Like its predecessor, the second-generation Boss 302 was upgraded with stiffer springs, larger sway bars, and enhanced aerodynamics. Along with the upgraded bodywork, the latest Boss 302 boasted a unique appearance package with some nods to its heritage, including C-shaped competition stripes on the sides of the car. And like the original, the S197 Boss 302 was a brief affair. Ford would cease Boss production after 2013.

Although the Boss 302 nameplate has been absent from the Mustang roster for the past few years while the Shelby GT350/GT350R and GT Performance Packages currently fill that niche. However, hope springs eternal that the Boss might reappear again soon.