5.0 Mustang & Super FordsNews & Views
2013 Ford Shelby GT500 Trinity 5.8L V8 - Power Of Three
How Ford's Special Vehicle Team stuffed 100 extra non-gas-guzzling, emissions-legal, Warrantied horsepower into the 2013 Shelby GT500 engine
|Bore Spacing:||100mm (3.937-in.)||100mm (3.937-in.)||100mm (3.937-in.)||100mm (3.937-in.)|
|Bore:||90.2 mm (3.544-in)||92.2mm (3.623-in.)||90.2mm (3.544-in)||93.5 mm (3.674-in)|
|Stroke:||90.0mm (3.537-in.)||92.8mm (3.653-in.)||105.8mm (4.165-in.)||105.8mm (4.165-in.)|
|Deck Height:||227mm (8.937-in.)||227mm (8.937-in.)||256mm (10.079-in)||255.71mm (10.049-in)|
|Con Rod Length, C to C:||150.7mm (5.933-in.)||150.7mm (5.933-in.)||169.1m (6.658-in.)||169.1m (6.658-in.)|
The Hidden Team
We never make a trip to Ford Motor Company without being overwhelmed by the scale of the company and the number of bright, hard-working people employed there. It's a feeling impossible to describe or address by listing everyone involved even in just one engine project. Even at SVT, where the total personnel count is just under 50 employees--and almost entirely engineers we might add--it's impossible to know everybody who contributed to the 5.8 engine. That's because the Special Vehicle Team is part of Ford Motor Compay and fully integrated with the greater company's awesome resources. So while we're able to highlight a mere handful of key 5.8 players in this story, there are many others throughout Ford who lent critical expertise. Two of those, both Ph.D.s based in Ford's "mainstream" engineering campus, were cited by the troops at SVT as important to the 5.8--Jagadish Sorab, Bottom End Technical Specialist specializing in short-blocks and rotating components, and Kevin Tallio, Top End Technical Specialist, who handles cylinder heads, gaskets, and valvetrains.
Primary to raising the power of the new 5.8 was increasing supercharger output, and SVT didn’t waste any time moving from 9 pounds in the 5.4 to 15 pounds in the 5.8. The mid-teen boost figure is no surprise for an all-out factory effort; numerous aftermarket builds have shown 15 pounds of boost is near or at the realistic limit for readily available 91-octane premium gasoline and the Four-Valve modular architecture.
SVT's options on how to produce 15 pounds of boost were certainly technically numerous, but practically speaking, the proven, cost-effective, and OEM-certified family of Eaton superchargers was the only logical option. And while SVT could have continued with the Eaton-built M122 Roots blower on the Condor 5.4-liter engine, the 2.3-liter Twin Vortices Series also sourced from Eaton is more efficient at these elevated boost levels.
By more efficient, we mean the 2.3-liter TVS blower requires less horsepower to drive, and at these higher boost levels it heats the charge air less. These are not inconsequential considerations, either, as SVT says it takes right at 100 hp to drive the 2.3 TVS at its maximum output. That's 100 hp the 5.8 engine must produce but is never seen by the rear tires. In other words, if the 5.8 is rated at 650 flywheel horsepower, its internal parts are producing at least 750 hp just when considering the supercharger drive requirements. That also means the engine is consuming 750 hp worth of gasoline, but that's all part of the fun.
Anecdotally, the SVT engineers guesstimate a more accurate power output of the core 5.8 engine is well over 800 hp.
Another yardstick is motor friction--how much torque it takes to rotate the 5.8 engine at high speed without the engine running. The 5.4 GT500 engine required 150 lb-ft to motor, the 5.8 consumes 225 lb-ft, and these figures do not include making boost--that's just the effort required to turn against compression, the valvesprings, oil pump, crankshaft seals, supercharger and other internal drag. The extra force required by the 5.8 is explained by incremental increases in many things such as the higher compression ratio, greater valve lift, and increased oil volume.
SVT could have switched to a screw supercharger in search of a little more efficiency than the TVS, but at great cost. The screw blowers are the last word in positive-displacement superchargers, but thanks to complicated, difficult-to-manufacture rotors, they are more expensive, something SVT would have had to pass along on the window sticker. We'll all get to see how this supercharger showdown plays out when the aftermarket inevitably fits the giant screws it has waiting on the 2013 GT500.
As the mechanical details of the 2.3-liter TVS supercharger are generally well known, we won't dwell on its construction other than to note it uses four-lobe rotors with 160 degrees of twist. By comparison, the M122 blower on the 5.4 uses a less efficient three-lobe, 60-degree-of-twist rotor pack. SVT worked with Eaton to fine-tune details of the 2.3 blower, especially at the inlet, but generally the big Eaton was fully developed when SVT selected it for the GT500.
As is normal with the Eaton superchargers, the SVT 2.3-liter blower uses a pressed on blower pulley, and at 69 mm (2.71 inches) in diameter it's already pretty small. In fact, the blower input shaft had to be machined slightly undersized from normal Eaton practice to fit the small pulley. SVT says typically Eaton would not fit anything smaller than a 72mm pulley to the 2.3, so it would seem SVT has the 2.3 wick turned up already. By comparison, the M122 on the 5.4 carries a 78mm (3.06-inch) blower pulley.
No matter how efficient the supercharger, higher boost means higher supercharger discharge temperatures. In addressing these elevated temperatures SVT not only wanted to add enough charge cooler to keep up with the increased boost, they wanted more additional cooling to ensure lap-after-lap consistency in the air-charge temperatures.
Their solution was a much larger radiator in their existing air-to-water charge cooling system. Described as "a touch wider, much taller, and definitely deeper" than the 5.4 heat exchanger, the new unit is said to be almost twice as large, and SVT literature says the 5.8's air-charge cooling capacity is more than double the 5.4's, so open-track fans should be pleased. SVT also says a new electric pump is used, and, as before, it's thermostatically controlled by the engine-management computer.
Additionally, while it doesn't have much to do with cooling the air-charge temps, the intercooler under the supercharger has been upgraded to be less restrictive to the charge air passing over it.
Also apparently all-new but beyond the scope of this article is the fuel system. At the engine end, the injectors have moved up from 46.7 to 54.8-lb/hr units, but SVT says the entire fuel system feeding those injectors is new, including a plastic fuel tank, new pickups, pumps, and an all new Fuel Pump Driver Module, which they claim every Mustang tuner headed for big numbers will go out and buy. We don't doubt it, as SVT has sold more 5.4 FPDMs to tuners than they have to the assembly plant.
As we go to print, SVT has released no official horsepower or torque curves--no dyno sheets of any kind. Some of this is marketing, but it's also early yet as the official SAE rating tests are just now being run. But SVT shows every confidence of meeting the 650 hp and 600 lb-ft of torque targets, so the wait is going to be worth it.
Or, as Jamal Hameedi said, "It's like a diesel. We're not ready to publish the torque curve, but when you see it, you'll be amazed at just how broad the torque curve is, even more so than the 2012 engine. It absolutely is a stump-puller. And it revs to the moon as well.
"Take the best attribute of every kind of engine you may have ever experienced and throw it into one engine and it makes driveability fantastic. [The] performance is fantastic."
Horse Sense: Trinity was the code name for the United States' first nuclear test and was one of the best kept secrets in history. Ford chose the same code name for the 2013 Mustang Shelby GT500 project because it wanted the same level of secrecy--and probably the same over-achieving gain in power.