Indeed, the budget was so tiny, at least by Big Three standards, that it was described to us as a CCP--a credit card project--with most of the time spent in accomplishing it coming after regular business hours, or in the spare time of the can-do crew at Powertrain Research & Advanced Engines. You see, it was these guys who initiated the idea in the first place. They developed it on their own time as a project, researching possible means of providing a displacement increase to the short-deck 4.6 for applications where the taller deck (and subsequent increased width) of the 5.4 or 6.8 won't easily fit.
By adding the 25-percent displacement increase of two extra pots onto a281, you get 351 ci
You won't find much argument around here that the little 281 could use a few more cubes. Because a major bore increase is not possible due to the modular's extremely tight cylinder spacing, it seemed a practical experiment, they reasoned, to gain that extra displacement by cobbling together a V-10, especially since this same compact bore spacing would result in an increase of less than 4 inches (100 mm, to be exact) in overall engine length. And to help, uh, expedite matters, they decided to go ahead and build one and tell their corporate bosses about it afterward.
Unlikely as it sounds, these professional tinkerers got underway by cutting apart some existing 4.6 V-8 sand-casting cores and literally gluing them back together in V-10 form. They repeated this cutting-and-pasting process on Cobra R head cores, poured in some molten aluminum, and--voila--they had their basic castings. In comparison to having all-new tooling made up, this process was incredibly cost-effective. They calculated that 5.4 Cobra R cam specs should be fairly close, so they had new, longer billet bumpsticks made in that grind. And, since they had stuck with the stock 4.6 bore and stroke, they were able to use Terminator Cobra H-beam rods, connected to pistons of about 10:1 compression that they "had lying around from another project."
The Cobra R hood looks cool, but it isn't a requirement for aV-10 Mustang.
The billet crank spun by those slugs is an interesting piece, again bearing no resemblance to the one in the truck 6.8 V-10. We'll let V-10 project lead Kevin Byrd describe it. "The 6.8 truck crank is a split-pin crank, like you'd find in a 60-degree V-6. [For the 5.8 V-10] we went to a common-pin design based off the Cobra crank, only instead of four pins, we have five. The crank is set at a 72-degree pin offset, but when you put that in a 90-degree block, it doesn't line up to a 72-degree firing. It ends up to be a 90/54, so you get that odd-fire sound, but it blends together beautifully."
We agree that the sound is both appealing and distinctive, unlikely to be mistaken for any old V-8, even though in the Boss 351 it's thoroughly muffled with four mufflers, along with two metallic and two ceramic catalytic converters. In one of the more challenging aspects of construction, five-into-three-into-one headers were bent up with no particular emphasis on performance, rather just something that would fit (using a tubular K-member made it all possible and took further weight off the nose).