The world's most powerful...
The world's most powerful production V-8, coming to a Ford showroom near you this summer. With its world leading power and incredibly wide powerband, the 5.8-liter V-8 promises to propel the '13 Mustang Shelby GT500 into a new level of Ford performance.
If you doubt there's a horsepower race going on, this article ought to clear it up. For all the green hubbub about soybean seat cushions and cars that plug into walls, the age-old truth that high-performance machinery is always in style has never had so much boost behind it.
And, quite literally, never has a Ford production gasoline engine had as much boost as the new 5.8-liter V-8 in the 2013 Mustang Shelby GT500.This new development of the modular engine family is the most powerful production V-8 in the world. That's quite a claim for a mass producer such as Ford, but the perfect accomplishment for its in-house performance arm, the Special Vehicle Team.
While the engineering boss in the corner office at SVT, Jamal Hameedi, notes his team's goal wasn't setting a world horsepower record, they knew they had to go big when upgrading the GT500 Mustang. Not only were the other guys in town working hard on their ZL1, Ford's own Boss 302 was edging toward GT500 performance. So the Shelby GT500, although impressively upgraded for 2011 with an aluminum block and 550 hp, was scheduled for a complete makeover as a 2013 model to go on sale in mid-2012.
This re-engineering of the GT500 is all-encompassing, covering handling, braking, performance, and aerodynamics. In fact, we sense the upcoming GT500 will still be a Mustang, but one galloping so far ahead of the traditional ponycar herd that it'll run more with thoroughbred exotics than everyday quarter horses. It's aiming to be the ultimate Mustang, and we'll eat its 10-rib blower belt without butter if it isn't.
Subtle machining is the only...
Subtle machining is the only difference between the Condor 5.4 and Trinity 5.8 cylinder blocks, which are whittled from the same casting. One change impossible to see is the 5.8's deck height is 255.71 mm versus the 5.4's 256.00 mm. That minor 0.29mm difference accommodates the 5.8's thicker headgasket. Another invisible change is in the water jacket cores. The 5.8's cores were lightly massaged in spots to increase coolant flow while maintaining wall thickness. But major locations of interest to hot rodders, such as bellhousing bolt patterns, head retention, water and oil pump locations, and so on, are identical to 5.4 practice.
The joys of driving the new GT500 are still months away for us, however, and Ford is still teasing us enthusiasts with details. But as part of the tease, SVT graciously agreed to give us the cook's tour through the Shelby's new 5.8-liter V-8; the story you are reading is the result. It's a story impossible to write without SVT's cooperation, and we know you'll add your thanks to ours in being granted all-access to SVT's engine building team.
For the record, the code name Trinity covers the entire 2013 GT500 car, so the new 5.8 engine is formally known as the Trinity Engine or 5.8-liter V-8. That's a little different from Coyote, which designates just the 5.0 TiVCT V-8 in the Mustang GT, or RoadRunner for the Boss 302 engine. Finally, for reference, the previous generation 5.4 GT500 engine is codenamed Condor.
While this story concentrates strictly on the new 5.8 engine, it's important to remember the engine is part of an expansive, whole-car upgrade. SVT's goal was to transform the 2013 GT500 into a no-excuse super-Mustang, something far more complex than stuffing the largest displacement possible under the Mustang hood and heading to the dragstrip. Not only must the new GT500 be world-class fast in a straight line, it also must stand clearly atop an increasingly sophisticated Mustang lineup that includes the already potent Mustang GT and the fabulously well-rounded Boss 302. And haloing a Boss 302 in every category is going to take a lot more than a smaller blower pulley.
As Jamal Hameedi explains, "...this project didn't start out trying to outdo anyone or anything. It was really about keeping the separation in the Mustang line-up. Just like Porsche has the 911 and a GT3, which is track-focused--not the crazy power but a good, agile balanced car, an all-around good track car--and then you've got like a GT-2 which is... the fastest in the lineup on a track, in a straight line, top speed and everything. ...It's the same thing with a [Corvette] Z06 and a ZR1. ...but we did such a good job with the Boss that it was pretty close to the Shelby GT500, and so what we wanted to do was... keep that separation from the Mustang GT to the Boss to the Shelby GT500."
Unsaid but obvious, keeping the GT500 relevant includes not only topping the Mustang line, but also the Camaro offerings. With Chevy finally announcing the long-anticipated ZL1 at only 580 hp, the SVT team no doubt confirmed to themselves that they had made the right choice in going for all they could under the hood.
Brutally strong and amazingly...
Brutally strong and amazingly durable, this is what 650 showroom stock horsepower is made of. This early SVT publicity photo shows a few prototype parts such as the no-logo supercharger. It also displays the clutch, giving us the chance to note the 5.8 has moved from the 5.4's 250mm to a 260mm disc with upgraded materials for high-rpm use. Clamping force is also increased in the pressure plate to hang on to the additional torque.
Isn't this a spider of an...
Isn't this a spider of an oil filter adapter? Here we see the system configured with the oil-to-water “brick” heat exchanger and pressed-in hose nipples as used with standard cooling. With Track Cooling the oil thermostat replaces the “brick,” the hose nipples are deleted, and the spider is machined to accept SAE O-ring-type, threaded, stainless steel hose connectors. SVT says they don’t use AN fittings because they tend to loosen from vibration. The black hex seen under the “brick” is covering the pressure bypass loop (a spring-loaded pressure relief valve) used with Track Cooling. The same oil filter is used on all 5.4 and 5.8 engines.
Standard oil-to-water cooling...
Standard oil-to-water cooling uses the cooling system's thermostat to regulate both oil and water temperatures, but when oil-to-air Track Cooling is fitted, that thermostat is no longer available to the oil. Therefore an oil thermostat replaces the oil-water heat exchanger; it uses the same expanding wax pellet principle as the familiar engine coolant thermostat. This is a prototype of the oil thermostat--it's a billet piece for testing, but will be an aluminum casting in production. The thermostat is mandatory because water dilution (a normal byproduct of combustion) of the oil accumulates at low oil temperatures, plus the oil needs to be 180 degrees or higher for all its chemical additives to work properly.
When SVT sat down to set specific goals, they arrived at engine targets of 650 hp, 600 lb-ft of torque, a nominal redline of 6,250 rpm backed with an ability to momentarily over-rev to 7,000 rpm, and not invoke the Gas Guzzler tax penalty. While we aren't privy to Trinity's financial constraints, the 5.8 is a low-volume engine, so costs had to be tightly controlled. Exotic solutions would have to be paid for by relatively few customers, and we're sure Ford management is dedicated to keeping the GT500's sticker price competitive.
What SVT did to arrive at the 5.8 is start with the 5.4 GT500 engine and adjust it as necessary to support an initial goal of 640 hp. As the program developed, it was soon clear 650 hp would be just as easy to hit given the changes being made, so the target was officially bumped to 650 hp.
Compared to the now familiar Coyote 5.0, which was essentially a clean-sheet-of-paper design that owed next to nothing to the previous 4.6 Three-Valve starting point, it's tempting to say the 5.8 is a stretched 5.4 with the boost turned up. In fact, when described in overview, the 5.8 is indistinguishable from the 5.4 starting point. Like the 5.4, the 5.8 is an all-aluminum V-8 with double overhead camshafts, four valves per cylinder, a belt-driven supercharger, and air-to-water charge cooling. Like the 5.4, the 5.8 does not use variable cam timing, much less twin independent cam timing, nor does it use direct fuel injection. Indeed, the 5.8 does use the same fundamental architecture of the 5.4, meaning basics such as the bore spacing, nominal deck height, pan rail width, cylinder head design, and so on, are identical.
However, scratch just below the surface of the basic architecture and an amazing number of details differ. It's those details that make up this story, and they are there to support four major changes: greater displacement, significantly higher boost, piston oil squirters, and higher rpm.
So the 5.8 is it's own engine. Few components interchange between a 5.8 and a 5.4. However, even if they physically bolt on, the power of the 5.8 is in a different league than the 5.4. As a quick measure of that, the Condor 5.4 runs 9 pounds of supercharger boost; the Trinity 5.8 runs 15 pounds.
An overview of the bottom...
An overview of the bottom of the 5.8 block shows no changes at first glance. The main bearing caps and their six-bolt retention is carryover from the 5.4, as are the three shared PCV breathing and oil drainback passages visible on the inside of the block skirt. Also common are the three round bay-to-bay breathing holes in the bulkheads as modeled by the rear main bulkhead in this view, along with the oil pan rails, bolt patterns, and such. Get close and there are differences, however. SVT notes the 5.8 main bearing caps have an extra chamfer on them to ease assembly, but they remain interchangeable with the 5.4 version.
It's impossible to see a lip...
It's impossible to see a lip or edge between the parent aluminum and the 5.8's cylinder lining. The bore itself, however, looks and feels like iron--because it is. SVT says the Plasma Transfer Wire Arc process, which is finished with diamond hones and deck plates, helps make a dimensionally accurate cylinder. This facilitates the 5.8's tight piston clearance, which helps promote a tight piston ring seal. SVT also notes the 5.8's 93.5mm bore is the largest possible in this block.
Spotting the oil squirter...
Spotting the oil squirter hole in the main bearing bulkhead can take practice. The oil squirter itself is installed in a drilled passage underneath the main bearing insert. With the insert in place as it is here, the oil squirter is not visible, as it's buried in the bulkhead at approximately 8 o'clock to the bearing. The small groove in the bearing insert that feeds oil to the squirter is visible. Looking closely at the edge of the bulkhead, just before it reaches the cylinder bore and a little lower than the breather hole is a small slit. That slit is an angled passage from which the piston squirter shoots.
There's little mystery on how SVT ended up at 5.8 liters. From an engineering side, it's always easiest and least expensive to increase power via increased displacement, so the first move of an engineer with a directive to add 20 percent more power to an already highly stressed engine is make the engine bigger. The larger engine is less stressed at a given power level, and when talking about the most powerful production V-8 in the world, a little less stress is a good thing.
That said, marketing has to have played a large part in the 5.8's displacement. There's plenty of glory surrounding the 351ci displacement in Mustang history, a displacement that translated into 5.8 liters when Detroit went metric. Taking the historic theme a step further, the 5.8 is the perfect upscale displacement from the 5.0 in the Mustang GT, so you know management didn't waste any time landing on 5.8 liters of displacement for the GT500 engine.
How to achieve the extra 400cc displacement over the 5.4 must not have taken long, either. The 5.4 V-8 is already physically constrained in stroke, both inside the crankcase and outside, as a physical package that must fit a Mustang engine compartment. In the crankcase, the careful juggling act of stroke, piston height, rod length, and crankshaft counterweight clearance is already pretty well played out in the 5.4. Lengthening the stroke would quickly crash the pistons and crankshaft counterweights, leaving the other stroke-increasing option of raising the deck height. But raising the deck height on a V engine means making the engine both taller and wider, an impossibility given the Mustang's engine-bay dimensions.
If a longer stroke was out, then a bore increase was not without issues, either. As detailed in our Coyote and RoadRunner articles, Ford's multimillion-dollar investment in V-8 machining centers is not flexible when it comes to changing bore centers, and the modular engine family is thus fixed at 100mm bore centers. So, the SVT engineers couldn't stretch the 5.4's cylinders farther apart. Nor could they move over to the bigger architecture of the 6.2 V-8 as found in the SVT Raptor. That engine is too large for the Mustang engine compartment, plus it would be prohibitively expensive to design a better breathing Four-Valve cylinder head for it, as well.
That left increasing the 5.4's bore, an option open thanks to the recent maturation of spray-bore technology. This is a technique Ford has invested in for years and quietly debuted in the 2011 Shelby's aluminum block.