The Ford Mustang Boss 10.0L Concept Was SVT's 850hp Porsche-Beating Monster

• April 4, 2021
• Story By
  Benjamin Hunting

Factory-built dragsters are nothing new to the muscle car scene, but the pace at which these straight-line monsters began to hit the market definitely accelerated in the 1990s. With a horsepower renaissance lead by the Ford Mustang with its new modular V8, and the Chevrolet Camaro transitioning from the already-potent LT1 to tire-slaying LS1 engine family, engineering teams suddenly had a new treasure chest of parts to play with.

It was this atmosphere that helped give birth one of the craziest Mustangs of all time. Overseen by SVT director John Coletti, the Ford Mustang Boss 10.0 Liter Concept grabbed components from every corner of the Blue Oval's high performance universe, stuffed them under the hood of the recently redesigned sports car, and then crossed its fingers for traction as it tore down the quarter mile. 

(Almost) 10 Liters Of V8 Fury

That's not a typo: this particular mid-'90s Mustang truly did bring a whopping 9.9 liters, or just over 600 cubic inches of V8 madness to the table. The unit was assembled using an aluminum 429 cubic inch Special Vehicle Operations block that had been bored out by Roush and outfitted with a bespoke intake manifold, 72 lb/hour fuel injectors, and a pair of 70 mm throttle bodies. The heads were replicas of the same Boss racing units Ford had campaigned in NASCAR competition at the end of the 1960s.

Photo courtesy of Kris Walker.

It's no surprise that with that much displacement the Boss was a true torque monster. On a dyno it was good for a scary 850hp and 794 lb-ft of twist. Considering that the top-of-the-line Mustang Cobra squeezed just over 300 horses out of its own aluminum V8 that same decade, the Boss was truly a terror at full throttle.

Porsche Baiting Pony Car

Just how quick was the Mustang Boss 10.0 Liter Concept? At the drag strip the coupe was timed at a ludicrous 1.9 seconds in the sprint to 60 mph, with the quarter mile disappearing in a mere 10.55 seconds. Trap speeds for the Boss checked in at 135 mph on a well-prepped track. This made the Mustang quick enough to humble even the mighty 993 Porsche 911 Turbo of the time in a straight line.

Shuttling all of that output to the rear wheels was the responsibility of a three-speed C6 automatic, a further indication of the Mustang's drag strip persona. The chassis itself had been borrowed from one of Ford's test mules and then modified to help better put down the power with the throttle pinned. A set of Brembos were outfitted to the Boss to give it the required stopping power at the end of each quarter mile run, and the enormous 13-inch discs presaged the big brake packages that would come into vogue in the early 2000s.

Head-To-Head With The Bowtie 

Why was only one example of the Ford Mustang Boss 10.0 Liter Concept ever built? The answer is part business, and part technical.

Photo courtesy of Kris Walker.

The reason Ford got into the massive displacement Mustang game in the first place was because cross-town rivals Chevrolet were doing something similar with the Camaro. John Moss, who headed GM's Special Vehicles group (responsible for models like the Impala SS and the S10 Xtreme pickup of the same era, and later the SSR) had been experimenting with an aluminum-engine muscle machine of his own.

Photo courtesy of Kris Walker.

The 1993 Camaro that received the heart transplant was dubbed the 'ZL-1' in homage to the original classic aluminum-block coupe. The 572 cubic inch beast put out well over 700 horses itself, and was seen as a direct provocation at Ford that lead to the creation of the Boss. A few years later, Car and Driver would later pit the two vehicles against each other on a drag strip, where the cars finished in a dead heat (although there was some question as to what, exactly, the Camaro was running under its hood for that particular test). The thing is, Chevrolet never intended to actually put the ZL-1 into production, and the one meeting of the minds would be the only confrontation between the two big block battlers. Absent this rival, the bean counters at Ford decided to pull back from pursuing its drag program, which wouldn't regain traction until the early 2010s with the rise of the Cobra Jet project.

The dollars not making sense wasn't the only concern Ford had with the 10.0 Liter Concept. Reliability was also something of an issue. Notwithstanding the issues that hobbled the Mustang in its Car and Driver test, other testers of the day had trouble keeping the transmission on this side of functional after being forced to channel the big block's grunt.

There were enough problems with the finicky Boss setup that Ford decided to turn to another proven power-adder—supercharging—rather than pursue displacement when it came time to make the next monster Mustang (the '03 SVT Cobra, aka the 'Terminator). Today, the one and only 10.0 Liter Concept sits dormant in the Roush collection.