“My job is horsepower,” said Adam Christian, engine performance technical expert at Ford. And one glance at the numbers – 102 ponies per liter in particular – and it’s clear he and his team deserve a raise.
Christian is one of many proud parents that helped deliver the new 5.2-liter V8 that will be found under the hoods of Shelby GT350 Mustangs. This exciting powerplant delivers a breathtaking 526 hp, 429 lb-ft of torque and a redline north of eight grand; if you’re wondering, fuel cutoff is 8,250 RPM. “It’s absolutely a high-water mark for us,” he said, and the work it took to deliver these torrid figures is as extensive as it is impressive.
Flat Out: Inside the Shelby GT350 Mustang’s Engine
On the outside it may look like your garden variety 5.0-liter Coyote V8 found in the engine bay of a Mustang GT or F-150, but appearances can be deceiving. “This is a new engine top to bottom,” said Eric Ladner, engine program supervisor at Ford. The list of changes and enhancements compared to the standard five-oh are exhaustive.
And as you’ve no doubt heard, the most important update of all is the crankshaft. Engineers eschewed a traditional cross-plane arrangement for one that’s flat. Rather than having the throws arranged at 90-degree intervals the Shelby GT350’s are set 180-degrees apart. Flat-plane cranks are common in supercars like Ferraris where maximum performance is a top concern but this is the first time Ford’s ever offered one and they’ve been mass-producing V8s for more than eight decades, ever since old Henry’s first flathead rolled out of the Rouge foundry in 1932.
Ladner said, “Flat-plane cranks are inherently lighter than their cross-plane counterparts.” This is because bulky counterweights are not required to balance them. But he also cautioned that crankshafts account for less than 15 percent of an engine’s rotating mass, so this is hardly their only benefit.
SEE ALSO: Listen to the Shelby GT350R at Full Tilt
Beyond all of this, they “[allow] all the cylinders breathe the same,” said Christian, which makes tuning the engine much easier so they can run it closer to the ragged edge and get more power. Additionally, the Shelby GT350’s crank is made from forged steel for extra strength and it’s been “gun-drilled,” meaning holes have been punched through each of its throws to further cut mass. These openings also allow the adjacent bays inside the block to breathe together, further reducing parasitic drag.
Bored and Stoked
Another major change compared to lesser Coyote V8s is this powerplant’s internal dimensions. Giving it that extra 0.2-liters of lung capacity is a larger bore and longer stroke. The 5.2’s digits clock in at 94 millimeters by 93 millimeters, respectively. If you’re curious, a regular 5.0-liter measures 92.2 by 92.7.
Instead of traditional cylinder liners that are either pressed or cast into place the Shelby’s engine uses a plasma transferred wire-arc technology, which saves a significant amount of mass. Additionally its block is unique to this application but the bore spacing and deck height are identical to a five-oh so the same machine tools can be used. The GT350’s engines will be assembled on Ford’s niche line in Romeo, Michigan; standard Coyotes are built in Windsor, Ontario.
As for the bores themselves, they receive special treatment. Unlike more pedestrian engines, the new 5.2 is deck-plate honed, meaning special jigs are torqued to the block before the cylinders are bored to size. This is an old racing trick that ensures the bores are as round as possible when the head bolts are tightened down. “What that allows us to do is drop the ring tension,” said Christian, which significantly lowers friction, resulting in more power.
Filling those eight holes in the block are lightweight, forged-aluminum pistons. They have ultra short skirts and appear to be treated with some sort of oxide finish. The connecting rods are manufactured in a similar manner and feature fracture-split big ends.
These rotating components squeeze incoming air and fuel with a frighteningly high 12-to-1 compression ratio and apparently that’s ok. Thanks to exhaustive computer modeling the engine runs just fine on 93 octane pump gas and it doesn’t even have direct injection. According to Ladner this feature “wasn’t necessary to meet our performance targets,” plus DI systems are heavier and add cost.
Moving into the basement, this engine features a composite oil pan that saves more weight, about 20 percent in fact. But it’s hardly just a sump; it also contains an integrated pickup and windage tray, all in one unit. A higher-capacity oil pump ensures there’s plenty of lubrication at all times.
Taking an elevator ride topside, the Shelby engine breathes through an 87-millimeter throttle-body, the largest Ford’s ever fitted, as well as an open-element air filter. Beyond this there’s an all-new intake manifold. Its runners are both longer and larger in diameter than the ones found in the dearly departed Boss 302. This configuration bolsters torque production across the rev range and all told, 90 percent of peak twist is available at just 3,450 RPM.
The cylinder heads are where all the magic happens in modern engines and the 5.2-liter V8’s have received special attention. For starters they’ve been strategically lightened and weigh about 6 percent less than the ones that cap off a standard Coyote block. Beyond this, the engine’s enlarged bores allowed for even bigger valves to help get copious amounts of fuel and air into the cylinders and speedily evacuate spent exhaust gasses once the mixture’s gone off.
“We have large valves, we lift them very high,” said Christian. They pop open up to 14 millimeters. Ford’s twin-independent variable camshaft timing permits each bumpstick to be adjusted individually, which allows the engine to pull like a mule at low speeds and scream like banshee at high RPM. An active exhaust system ensure the GT350 can rip when required yet not drive you insane with droning noises when you’re commuting to work on a Tuesday.
Overall this engine is lighter than the 5.0-liter V8 on which it’s based and it puts out A LOT more power. And despite spinning beyond 8,000 RPM it has to meet the same durability requirements as any other Ford product. Accordingly it will be backed by the same warranty, so don’t be afraid to tickle that redline.
Priced to Move
With 526 high-winding horses and 429 lb-ft of torque the 2016 Shelby GT350 Mustang should be an easy sell to enthusiasts, especially if it drives as half an nicely as it looks. Perhaps best of all it delivers these figures the old fashioned way, by breathing the same atmosphere we do; there’s cheating here, no forced induction power adders to deal with.
And if there’s not enough to love about the new Shelby Mustang it’s also priced to sell. This car should be available for $49,995 including destination fees; naturally the GT350 R will cost a fair bit more. Still, Ford is bringing supercar performance to a broad spectrum of enthusiasts and they’re planning on building as many as they can sell so there should be no shortage of Shelbys.
Correction: A previous version of this story had one of the engineer’s names spelled incorrectly.
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