There is exactly one Ford Mustang V10 in existence. It lives in Ford’s Heritage Fleet in Dearborn, Michigan. It was built in secret, nearly crushed twice, and hid in the back of various garages for years — maintained on zero budget by the engineers who refused to let it die. It is one of the most interesting Mustangs ever built, and almost nobody knows it exists.
The Skunkworks Project Nobody Sanctioned
In 2002, a team of eight engineers inside Ford’s Powertrain Research and Advanced Engine Development group had a problem. Dodge had the Viper’s naturally aspirated V10. Ford had nothing to match it. So, without official budget or management approval, they built one.
The team started with the sand castings from Ford’s 4.6-litre Modular V8 and added an extra cylinder into the middle of each bank — not bolted to the ends, but engineered into entirely new castings from Ford’s Windsor, Ontario facility. The result was a 5.8-litre (351 cubic inch) DOHC V10 — a deliberate nod to the legendary Boss 351 of 1971 — fitted with quad cams from the Cobra R, a custom billet crankshaft machined for the build, and Cobra R five-chamber heads. The project had very little funding but a whole lot of passion behind it, as engineer Jim O’Neill later recalled: “No bosses, just a bunch of engineers building a car we all thought could go somewhere.”
The only available test mule was a 1999 Mustang GT already earmarked for the crusher after serving as a Cobra R development car. The V10 dropped in with new engine mounts and minimal chassis surgery. A Tremec T-56 six-speed manual and a Ford 9-inch rear axle completed the drivetrain.
What It Could Do
Numbers matter here. The V10 produced 426 horsepower and 400 lb-ft of torque, running an 11-second quarter-mile — naturally aspirated, no supercharger, no nitrous. At the time, the standard 4.6-litre Mustang GT was rated at 260bhp. The V10 was also around 60 pounds lighter than the aluminium-block 5.4 Cobra R, despite having two extra cylinders, thanks to its shorter-stroke, shorter-deck architecture. And the sound — engineers who drove it described an odd-fire growl that no V8 could replicate, closer to a Viper than anything wearing a pony badge.
Ford’s senior management were impressed enough to commission a larger-displacement version. A 600-horsepower 6.4-litre variant using spray-bore cylinder liners was sketched as a potential candidate for the second-generation Ford GT. But the global financial crisis arrived, programmes were slashed, and the V10 Mustang was quietly shelved. The prototype survived only because the team hid it for years in the back of different garages, maintaining it with no money and doing the work themselves.
Today, it sits in the Ford Heritage Fleet as one of 50 milestone vehicles on display at Dearborn — the only V10 Mustang Ford ever built.
The Triton V10 Swap Community
The Boss 351 concept inspired a devoted subculture of builders. Ford’s 6.8-litre Triton V10 — the truck engine that originally wouldn’t fit the Mustang — has since been successfully transplanted into SN95 and New Edge Mustangs by determined enthusiasts. Because the Triton shares the Modular engine family’s bolt patterns and mounts, the swap is achievable without cutting the shell — though it requires the oil pan from an E-Series van and some creative brake booster solutions. The result is a torque-heavy, deeply characterful Mustang that sits in a category entirely its own.
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