Twenty years ago, a small team of enthusiast engineers at Ford had an idea. The company needed a serious engine to compete with the Dodge Vipers and Chevy Corvettes of the world. Ford had a V10, but it was huge at 6.8 liters—and tall, too. That wouldn’t fit in either the Mustang, nor the Ford GT, which was also in secret development at around the same time. So, the perennial teenagers in the performance department got creative.



“There was less oversight then,” said Jim O’Neill, powertrain prototype build leader.

“Could you do something like that today?” I ask.

“Not a chance,” said O’Neill, before he and Greg Coleman, now in 5.2-liter performance engine systems, began laughing in unison.

Those two guys, plus a few more, took the sand castings for the 4.6-liter modular V8s that Ford was using in the Mustang GT and added two more cylinders. That came out to a 5.8-liter (351-cubic-inch) aluminum block, dual overhead cam V10 only slightly bigger than the then-current V8. The engine control computers, which Ford had on hand, think they’re running two I5s since thee V10 computer Ford had only worked with the Triton truck engine. The assembly managed to fit under the hood of a 1999 Mustang Cobra R mule that was stashed in the shop.

Jake Lingeman

The 351 heads were based on the Cobra R heads, and O’Neill and crew attached the engine to a T56 Tremec six-speed manual, a Ford 9-inch rear end and a rear axle with a 3.83 final drive. The suspension and brakes were beefed up, too. Saleen five-spoke wheels and a Cobra hood completed the package, which made this car sort of a sleeper.

A 5.8-liter DOHC V10. Jake Lingeman

It still is. It's 20 years later and I’m piloting this Boss 351 prototype through its home streets of Detroit. It delivers 426 hp at 6,500 rpm and 400 lb-ft at 5,200 rpm. It does the quarter-mile in just under 12 seconds, mega-fast for the time—and better than the supercharged regular Cobra—with a trap speed of 117 mph. But it isn’t the amount of power that’s most impressive, it’s the delivery.

On startup, the V10 rumbles to life with a metallic arcing sound that I could pick out as a Ford a mile away. I could hear it from my dad’s Thunderbird and Taurus, and it sounds similar here. The whole car shimmies with the power, and any sort of throttle application is met with vibrations from the steering wheel, seats and especially the shifter. It’s just one of the ways this old Boss and the new GT350 are similar.

The Ford Mustang Boss 351 rides on Cobra wheels and tires. Jake Lingeman

If you’ve ever driven an old Mustang, especially a Cobra, you’ll remember the clutch pedal takes an NFL linebacker’s legs to push it in. I had to move my seat up a few notches to get the torque from my knee to disengage the thing. Letting out the clutch, more vibrations come through the cabin, but it’s only really tough being precise in first gear. Once rolling, it takes a balloon-popping stab to get it down, but the gears change easily, even through the notchy shifter—another Mustang hallmark. The throw on the stickshift is also about three times as long as a modern car.

Power from the 351 comes on strong even in the lower rev ranges, but when I crest 5,000 rpm it feels like the whole thing is going to shake apart. But with good performance tires, though old, and strong Cobra brakes I’m feeling confident it can handle itself. Like I said, it IS sort of a sleeper. A few people caught wind of it and gave a semi-knowing look that said, “It looks like an old Mustang, but it’s too clean and that hood and those wheels look different.” I told a few of them the story behind it, and most appreciated the knowledge.

Jake Lingeman

The steering is meaty with its old-school hydraulic setup, and with those tires and upgraded suspension, the Boss kept itself in check, even with the solid rear axle. It was mostly comfortable, too, except for a little wheel hop on certain surfaces, but the classic Recaro buckets were perfect. As for tech, there is none, which always makes me a little wistful for my past rides.

Should Ford have built this car in earnest back in the early 2000s? Probably not. The Cobra that year would have set you back almost $40K. Putting this V10 in there would have bumped it well above that. Sure, people will pay $50K or $60K or $70K now for a Mustang, but in the G.W. Bush-era 2000s it would have been a monster payment. On the other hand, it would have dominated the performance market for a half decade, putting the Chevy Camaro and exiting Pontiac Firebird to shame. It still would have a hard time besting the contemporary Corvette, though.

This car garners lots of questions, if you’re in the know. Jake Lingeman

We’re glad the Ford folks stashed the Boss 351 and saved it. It’s a time capsule of a car that was built when there was still a little time and money for a skunkworks project like this. Hopefully in 20 years we’ll hear about another one—maybe a rear-engine Focus RS or a Ford GT-powered ponycar. We’ll happily drive that one, too.

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