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Roush P-51A Mustang Build - Taking WingWatching The P-51A, Roush's Most Powerful Mustang Ever, Take Flight From Its Hangar From the August, 2008 issue of 5.0 Mustang & Super Fords By Dale Amy Photography by Dale Amy
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Derek Riopelle, Larry Lindenmuth,... Derek Riopelle, Larry Lindenmuth, and Andy Reichenbach (from left) stand proudly beside one of their babies-a ready-for-shipment Roush P-51A. Five such teams of three technicians are responsible for building P-51As out of stock '08 Vapor Metallic Mustang GTs. They're assisted in this formidable task by an interior trim department that rebuilds and reskins the GT seats, as well as a joint-venture engine division that upgrades stock Three-Valve rotating and reciprocating hardware and adds the intercooled Roushchargers. Horse Sense: If you're like us, you can't help but take note of the "A" suffix. If you missed your chance to acquire one of the squadron of P-51As, we wouldn't be surprised to see a P-51B model take flight some time down the road. Lately, the public relations crew at Roush Performance has been exhausting the office supply of coffee and midnight oil, with press releases of new products and models popping up seemingly every time we open our e-mail. The latest and greatest special edition from the house that Jack built is the Roush P-51A. It's an almost inevitable model for the company, given the Cat in the Hat's personal affection for what's recognized as the greatest and arguably most beautiful long-range fighter aircraft of WWII: the P-51 Mustang. It's no secret that the indefatigable Jack Roush owns and flies a skillfully restored D model of the P-51, and he's in the long, pricey process of returning the tired hulk of an earlier and even more rare P-51B to flying condition-but maybe we should talk about the car. At 510 hp and an equal amount of torque, the P-51A is the most powerful Roush Mustang to date, and it's the first to include a fortified short-block as part of the deal. Similar to its airborne counterpart, it uses forced induction-in the form of an intercooled Roushcharger, naturally-to squeeze out as much as is safely possible from each power stroke. The P-51A benefits from a larger blower and higher boost than Roush's Stage 3, 427R, or 428R, thus explaining the rationale behind the muscled-up bottom end. Only 151 examples of the P-51A will be built, and apparently all of them are already spoken for. Construction began at Roush's Livonia, Michigan, production facility-known as the Plymouth Road Technical Center, or simply Roush building No. 50-in late February. Knowing what an inquisitive group our readers are, we thought you might be interested in what it takes to transform a stock S197 GT into Roush's ground-superiority fighter.  Building a P-51A is anything...  Building a P-51A is anything but a haphazard process, as the conversion is guided in exquisite detail by this reference manual. This type of repeatability and attention to detail is necessary in a vehicle that brings with it 510 hp and a three-year/36,000-mile warranty.  The starting point for each...  The starting point for each P-51A is an '08 GT Deluxe coupe, with cloth seats and relatively few factory dress-up options. By the time it morphs into a P-51A, it will be dressed up in Roush style, outside, inside, and underhood. Speaking of hoods, the stock ones are removed, the distinctive olive green stripe is painted on, and they're reclearcoated and reinstalled before the GTs even reach the conversion hoists.  Each Roush three-man build...  Each Roush three-man build team works simultaneously on two cars that are on a pair of assigned hoists. Why two hoists? So the teams don't have to wait around for the seats to be reskinned and the engines to be rebuilt and supercharged. By the time they get the powertrain and stock buckets out of the car on one hoist, the beefed-up powerplant and P-51A-specific seats are likely already back for the car on the second hoist.  On that note, one of the first...  On that note, one of the first disassembly steps is to remove the stock, cloth buckets and rear seats. These go to a dedicated trim department for reconstruction, as we'll see in upcoming photos.  As each car begins its conversion,...  As each car begins its conversion, generally one crewmember prepares the stock drivetrain for removal, another goes about the interior dress-up that's part of the P-51A package, while a third attends to the exterior makeover. Showing the true production nature of the process, note the template being used here to drill for mounting the wrap-around Roush rear wing.  To provide subtle contrast...  To provide subtle contrast to the P-51A's Vapor Clearcoat Metallic hue, the new rear wing and hoodscoop are finished in Ford's Satin Silver Clearcoat Metallic. This is reminiscent of the slight variation in panel coloration often seen on an aluminum-skinned WWII aircraft.  Meanwhile, the engine is prepared...  Meanwhile, the engine is prepared for removal, and all the components that won't be reused are unbolted and set aside for resale, including the air inlet and intake, fuel rails and injectors, coolant crossover tube, throttle body, and serpentine-belt tensioner. The engine/transmission will soon be removed from beneath by dropping the K-member.  Inside, the P-51A cockpit...  Inside, the P-51A cockpit is receiving a Roush electroluminescent gauge cluster, aluminum pedal trim, doorsill plates, carbon-fiber dash trim, and "P-51A"-embroidered floor mats. There's a lot of room to work in while the seats are out.  Up front, the factory fascia...  Up front, the factory fascia goes away in preparation for the P-51A's much more aggressive replacement. Notice that in preparation for lowering the K-member/engine assembly, the struts and front brakes have been removed. Both will be replaced with Roush upgrades.  Roush Industries built these...  Roush Industries built these hydraulic cradles specifically to ease removal and reinstallation of the S197 engine and tranny while still attached to the K-member. The removal operation is a team effort, with one man slowly raising the hoist while the other two simultaneously watch for issues and gently lower the cradle.  After some further component...  After some further component stripping, including unbolting the tranny, clutch, and factory six-bolt flywheel, the long-block is separated from the K-member and sent to the engine crew at Performance Assembly Solutions (see sidebar) for teardown and rebuild.  With the K-member still firmly...  With the K-member still firmly pegged to the cradle, the P-51A's 14-inch rotors and four-piston calipers are bolted in place, along with their braided flex lines.  Out back, the fuel tank is...  Out back, the fuel tank is removed while on the workbench, the GT fuel pump is replaced with a GT 500-style twin-pump assembly. This also requires the addition of a second pump-driver module and running some additional power wiring the length of the car. Note also that the P-51A's Stage 3-spec rear suspension components are mostly installed here. Only the rear brakes remain to be upgraded. Roush Stage 3 suspension hardware (except for the springs) is red; Stage 2 counterparts are blue.  Behind the P-51A's assertive...  Behind the P-51A's assertive fascia, the area behind the new grille has been sprayed satin black so it blends in; the intercooler heat exchanger and pump have been installed and plumbed.  The GT engine harness receives...  The GT engine harness receives some needed modifications on the work bench, including relocating the air-charge temp function from the mass air meter to a separate sensor that detects blower discharge temperature. The throttle-position-sensor harness is repositioned to account for the new throttle body location.  Meanwhile, in the interior...  Meanwhile, in the interior trim department, the front and rear seats are disassembled and deskinned of their cloth upholstery. On the buckets, the bottom cushion foam is retained and the seatbacks receive a new, more supportive foam structure.  Here, Matt Rogers removes...  Here, Matt Rogers removes the old foam from the passenger-side seatback. The rectangular black box on the frame is the side airbag.  The P-51A seatback foam in...  The P-51A seatback foam in the foreground is more aggressively bolstered than the factory GT foam. It also has a different profile in the shoulder area.  During the reupholstery phase,...  During the reupholstery phase, a steam wand is used frequently to soften the new leather/suede covers and work out any wrinkles. The rear seats get matching upholstery, minus the "P-51A" embroidery. All the crew in the trim department seem genuinely obsessed with the quality of their work, to the point of being competitive with one another. By the way, the set of seats that originally came out of the car are what go back in.  In true OEM-quality fashion,...  In true OEM-quality fashion, Roush doesn't mess around. The passenger bucket has a load sensor to determine passenger weight. In the event of an accident, if there is less than 54 pounds on the seat, the passenger-side airbag will not fire. This is a safety measure for small children, who can be injured by airbag deployment. Before going into the P-51A, the reworked passenger seat is put on this computerized test rig to be sure the load-sensor calibration hasn't been affected by the seat modifications.  Once the engine comes back...  Once the engine comes back down the hall from Performance Assembly Solutions, it gets dressed for reinsertion into the waiting P-51A. Notice that the tranny, tranny mount, H-pipe, and new Roush/Hurst shifter are already in place before the elevator goes up into the engine bay. With the powertrain back where it belongs, a cold-air induction system is added. Notice the relocated alternator on a Roush-cast bracket. Almost all that's left to do at this point is to reflash the processor with the P-51A-specific calibration. We've skipped about a million steps, but now you have an idea of what it takes to essentially assemble the highest-powered Roush special edition to date. After observing the whole process, we'd love to tuck a P-51A in our hangar. Though located within the same Plymouth Road Technical Center, engine teardown and assembly for the P-51A is the responsibility of Performance Assembly Solutions, a joint-venture established by Roush Industries as an assembly supplier of niche and specialty powertrain modules. Yet another example of Roush business diversity, PAS is in the business of building engines for a variety of corporate clients, some of which might surprise you. For the P-51A, the same engine that comes out of any factory GT goes back in, only with a much stouter bottom end and a Twin Vortices Series Roushcharger on top.  Disassembly comes first, with...  Disassembly comes first, with the new GT Three-Valve modulars stripped down to their bare blocks. Their pistons, rods, six-bolt cranks, and crank dampers become orphans.  Forged Mahle pistons-made...  Forged Mahle pistons-made to Roush specs with a 16cc dish for about 8.6:1 compression-replace the factory 9.8:1 hypereutectic slugs. Phosphate-coated and with Mahle's Grafal skirt coatings, these are of standard-bore diameter; there's no need to bore or even hone the factory-fresh aluminum blocks.  The P-51A's steel H-beam rods,...  The P-51A's steel H-beam rods, sourced from Manley, are basically clones of those used on the '03-'04 Terminator Cobra, and we know how tough those are. ARP 8740 rod bolts are used, along with Speed-Pro main bearings.  Likewise, the forged-steel...  Likewise, the forged-steel Kellogg cranks are the same eight-bolt units as were installed in the Terminators. There's no sense reinventing the wheel-when you have a crank as proven as this one, use it.  Once the long-block is fastidiously...  Once the long-block is fastidiously reassembled, the icing goes on in the form of a 2.3-liter Eaton TVS Roushcharger. It sits atop a Roush-cast lower intake, which houses the air-to-water 'cooler elements. The setup also gets an application-specific fuel rail and 52-lb/hr injectors, and it breathes through a GT 500's dual-60mm throttle body.  The P-51A's new eight-bolt...  The P-51A's new eight-bolt aluminum flywheel is an SFI-approved McLeod piece. An upgraded clutch disc is also part of the deal, though the stock pressure plate remains.  For use under boost, plugs...  For use under boost, plugs are gapped down from 0.041 to 0.032 inch. By the way, a welcome running change (that occurred sometime around January) in factory Three-Valve engines is the swap from the hard-to-gap and hard-to-find 14mm closed-electrode plugs (top) to a 12mm plug with a more traditional electrode arrangement.  Every P-51A engine assembly...  Every P-51A engine assembly is cold-tested to check for leaks and correct oil pressure. Each cylinder is also compression tested.
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