2020 Ford Mustang Shelby GT500: 4 Pearls of Performance Wisdom

Computer Helped Optimize GT500 Lap Times And Design

"The performance team always has less time to do its job, because it can't start until a design is almost fully engineered," Widmann said.

Computers helped his team hit the GT500's launch date. He uses a program that fairly accurately predicts lap times at Virginia International Raceway as the team programs in a vehicle's hard points and tunes for factors such as differential torque bias, tire characteristics, aerodynamics, etc. Early computer twiddling resulted in the team assigning Michelin a fresh set of tire-performance targets (the front tires are especially critical at VIR) and Torsen a new torque bias requirement. And determining the aero requirements far enough in advance of launch gave the design team time enough to integrate the various elements so that nothing looks aftermarket or tacked on. "We are finding that its looks are selling this car—that's not always the case with high-performance variants," he said

Strongest Block Wins

"Engine structural advances are driving the horsepower wars," Widmann said, noting that nobody is investing in all-new scratch-built V-8 engines these days, drastically altering bore-center spacing and so forth. Iron cylinder liners are ditched for microns-thick plasma-spray coatings, as everyone scrabbles for every micron of bore diameter. To withstand the insane in-cylinder pressures that generate 850-plus hp in the GT500's cylinders (which boils down to "just" 760 horses at the crank, after the supercharger, alternator, and other engine parasites leach their shares), Ford's four cylinder-head bolts per cylinder are super long. They reach way to the bottom of the block, and they get "torqued to turn," or "torqued to yield" (rendering them good for one torqueing only). This design is just as effective as the race-shop technique of torquing on a fake cylinder head through which the cylinders can be honed under load. Failure to use either method can result in oval-shaped cylinders in which the rings can't withstand high pressures.

Dual-Clutch Is More Efficient Than The Manual

These days we're doing a lot more dynamometer testing, so we pressed all the Ford powertrain folks on hand at Woodward: What should we use as a driveline efficiency percentage? The doublespeak that ensued made us cross-eared, and everybody dummied up. "You measure at the wheels, and we'll give you the crank number," said Hermann Salenbauch, global director of Ford Performance vehicle programs. That suggests the GT350 you rate at 526 crank hp that we just dyno-tested at 494 hp suffers 11 percent losses through its six-speed manual's 1.00:1 fifth gear. Well, I guess we should expect to see north of 684 hp at the rear wheels when we finally strap a GT500 to the rollers, because the team claims the seven-speed dual-clutch transmission suffers fewer losses than the six-speed manual.

Tall, Wide Ford Engines Must Rev!

"We always demand that our engines make 90 percent of peak power at redline," said Widmann. That's the Ford recipe for a fun-to-drive engine, and oh by the way, the redlines also need to be high, like 7,500 to 8,250 rpm. Said recipe dictates four-valve cylinder heads and dual overhead cams, making Ford engines taller and wider than their pushrod GM counterparts. High revs put lots of stress on engine components, too, so the development engineers have to really do their homework. "You know why Crown Vic powertrains were SO reliable? They weren't FAST!" Widmann quipped.