Admit it, you already know why someone would put an Aston Martin Vanquish V-12 in an S197 Mustang. The real question is, how?
That was the first query we put to Shannon Wall of Western Motorsports in Calgary, Canada. The answer was simple enough. Several years ago, he and business partner Dave Lockwood stumbled across a couple of 6.0-liter V-12s in Dearborn while talking to a Ford salvage technician. The aluminum wonders were in a dusty pile of unloved test engines at a Ford warehouse, and the company was willing to part with them for a few dollars. Shannon and Dave decided a pair of V-12s would be neat in something someday, so they bought them.
When the new Mustang came out in 2005, Shannon knew someday had arrived, and something was at hand. Taking the long route to individualism, a body-in-white S197 shell was obtained from Ford Racing, a wrecked '05 Mustang was purchased locally for the small parts, and building began inside the Aston V-12.
Although it generally showed limited running time, the Aston had spun rod bearings. It was also stock, meaning it had weak powdered-metal Duratech V-6 connecting rods, so-so pistons, and surprisingly ratty port castings in the heads. Wanting more than stock power and needing a stronger rod, Shannon and Dave opted for undersized rod journals, slightly longer Eagle rods, ARP hardware, and a small bump in displacement to 6.1 liters. JE supplied the forged pistons, which were mated to carefully cleaned-up cylinders. Thanks to the stroke, lack of dish in the new pistons, and 0.005-inch clean-up milling on the cylinder heads, the compression came close to 11:1. The stock cams, springs, and some other things were retained, but in a torpid-inducing grind, the ports were hand-massaged and all 48 valves and seats were treated to a three-angle valve job.
The intake manifold is stock but modified. This V-12 was a prototype with an intake that had been cast as one piece, cut in two sections, then welded back together by Ford when the separate intake plenums didn't help airflow. Western cut out Ford's hack job, carefully rewelded the manifold into one unit, cut and rewelded the twin throttle-body mounts for forward-not sideways-facing throttle bodies. Two Accufab 75mm throttle bodies were fitted and a pair of oval air filters and tubes were fashioned using two of Western's '05 Mustang inlet kits as starting points. Shannon notes that both breathe through the grille and Colecraft hood vents. Colecraft supplied the fender vents as well.
Shannon and Dave hand-fabbed the headers by cutting off all but the first 6-8 inches of the Aston manifolds-the downstream portions looked restrictive anyway-and started fitting various bends, straights, and collectors until they had their headers. That's glossing over a lot of work, as the six primary tubes per side convolute into two pipes, then a single pipe, plus the engine was in and out of the chassis about 10 times in the two weeks it took to finish this part of the project.
Once finalized, the mild-steel headers were coated with ceramic. Magnaflow parts were employed to build a 3-inch X-shape crossover with an off-the-shelf Magnaflow after-cat.
Fueling the V-12 is done with a stock fuel tank and a 255-lph old-school Walbro pump with return line. This can be thought of as part of the engine management system, composed of two SDS speed-density computers firing both injectors and two MSD DIS-4 spark boxes.
Conceptually, the twin computer system is the same as the original Ford/Aston twin-ECU system that ran the V-12 as if it were two in-line six-cylinders sharing a crankcase. The SDS computers are plug-and-play units Western has found easily sourced, installed, and tuned for Mustangs and Ford trucks. The two SDS and two MSD boxes were mounted in the trunk stereo-style, reducing front-end weight and putting something more useful than bass amps in the back. The entire car was custom wired by Shannon and Dave, using wire and terminal ends from their donor Mustang.
An oft-asked question is if their Frankenstein combination of stock and custom electronics has befouled the S197 Mustang's computer network. The latest models employ a bus and junction box to form a local area network, and the common thinking has been that nothing would work-such as the window drop upon the door opening or closing, locks, lights, sound system, and so on-if the stock computer was not in place. Western found that everything works fine, as long as the smart junction box is retained and there are no dead ends in the wiring loom from functions or motors they omitted. Seemingly endless hours of stripping old looms, converting wiring connectors, taping new looms together, installing, and testing went into making this car a reality.
Of course, your question is, does it work? We think so. At this writing, all small functions such as lighting and windows have been sorted out, but the engine is not running, despite the photographic magic lensman Thawley wrought for this article. Nor has the engine been proven on a dyno, so the question of power output is still unknown. Shannon figures the port clean-up was worth 40 to 50 hp alone because the ports were bad as-cast. With the compression, headers, and freer-flowing intake, he's prognosticating an approximately 600 hp rating from the 372ci V-12. That's 1.6 hp per cubic inch, which is doable given good breathing and rpm. It ought to sound righteous, too.
Channeling snappy power is McLeod's standard dual-disc clutch and customized 157-tooth, 5.0 Mustang aluminum flywheel. The smaller flywheel is necessary due to the small-diameter Aston Martin bellhousing. The hydraulic '05 Mustang throwout bearing was retained.