When Ford introduced the Mustang Shelby GT350 in 2015, it was the pinnacle of Mustang-ness thanks to its 5.2-L DOHC “Voodoo” V8 that featured a flat-plane crankshaft design to enable sky-high, carefree revs (the GT350’s 8200-rpm redline is one reason Ferrari has long specified flat-plane V8s) and a rollicking 526 hp at 7,500. Then there’s the exotic “rip” unique to flat-plane V8s.
But contemporary musclecar development times seemingly are as quick as their ever-dropping 0-to-60 mph runs—and before Ford released the Shelby GT350, its 526 hp already had been eclipsed by the 707-hp supercharged 6.2-L Hemi V8 in the Dodge Challenger SRT Hellcat and later the 797-hp Hellcat Redeye. Prior to all this, General Motors’ Chevrolet started the hyper-power frenzy by deriving 650 hp from the supercharged 6.2-L OHV V8 launched for the 2012 Camaro ZL1.
So in early summer, Ford confirmed its newest entry in this arms race, another 5.2-L V8—but supercharged and with a conventional crossplane crankshaft—that generates a thumping 760 hp and 625 lb-ft (847 Nm) for the 2020 Mustang Shelby GT500. Adding intrigue, the supercharged V8 is backed by a new, Tremec-built 7-speed dual-clutch automated-manual transmission. In early August, Ford offered the media a look at some of the new driveline’s details.
Hand-built ‘supercar performance’
The new 5.2-L V8 is based on the GT350’s engine, said Patrick Morgan, powertrain manager for Ford Performance, but as well as the more-conventional crankshaft layout, almost every internal component is changed, he added. And like the GT350’s V8, each is hand-built by a pair of technicians at Ford’s plant in Romeo, Mich.
The redline is still an ambitious 7500 rpm thanks to 6-bolt main bearings, all-new forged-steel connecting rods and pistons, uprated valves and valvesprings and even longer cylinder-head bolts. The specially-ported heads “are an evolution of what we’ve done with the GT350,” said Morgan, who added that although the engine remains port fuel-injected, engineers have studied the potential for direct injection and the increasingly population combination of port and direct injection.
Also to enhance durability, the engine’s oil pan is structurally tied to the transmission (the 11-quart oil pan features clever passively-moving baffles that keep oil directed to the center sump during high-g cornering). The aluminium cylinder block’s bores are spray-coated. Compression ratio is a modest 9.5:1 and the Eaton 2.65-L supercharger operates at 12 psi—while its reverse-flow design pulls airflow from below rather than above. To cool it all, the GT500’s frontal intake area is 50% larger than the GT350, the better to feed the six distinct heat exchangers 760 hp demands.
Morgan summed up the GT500 and its claimed 1-100-0 mph time of 10.3s (Ford steadfastly refused to commit to a figure for the car’s 0-to-60 mph acceleration) by saying the GT500the most-powerful street-legal Ford ever offered—is for “the true ponycar enthusiast who wants supercar performance.” He added the car’s validation included more than 5500 laps at racetracks across the U.S.
First Mustang dual-clutch
The Tremec TR-9070 DCT 7-speed dual-clutch transmission was specified largely for its ability to deliver fast and smooth shifts, said Morgan. The design has five friction plates for the odd-gear pack, while gears 2-4-6 have six friction plates. Although it’s a wet-clutch design, Ford said transmission fluid is applied to the clutch surfaces only during “thermal events” to minimize parasitic losses and optimize cooling.
The TR-9070’s electrohydraulic shift mechanism employs low-leak solenoids that can execute shifts in as little as 80 milliseconds if the driver selects sport mode, one of five distinct modes (normal, sport, track, drag, launch) of automatic operation. The transmission of course can be manually shifted via steering-wheel paddles.
The transmission’s final drive is 3.73:1 and power flows through a Torsen limited-slip differential. The 2020 Mustang Shelby GT500 goes on sale later this year starting at $73,995 “all in,” Morgan grinned, although a Carbon Fiber Track Package can be selected to hike the price for those who must.Continue reading »