Richard Holdener
October 12, 2012

As production powerplants go, the new 5.8L Shelby engine is one serious piece of hardware. Some may put it down to the simple application of displacement and boost, but that is, at best, only a portion of an extremely complex equation. Ford engineers applied a tremendous amount of technology to ensure that the increased displacement, boost, and power level measured up to rigorous production standards. The benefit to us mortals is 662 hp and 631 lb-ft of torque, and a foundation capable of supporting a whole lot more. We are literally salivating at the thought of a combination that started out with an extra 160 hp over the last Shelby!

Before getting to the inevitable Kenne Bell blower upgrade for the new GT500, we should take a quick look at what separates this Trinity version (also the top secret code name assigned to the first U.S. nuclear test) from the previous 5.4L Condor combination. Here at MM&FF, we have stressed time and time again that the best route to a powerful supercharged engine is to start with a healthy normally aspirated model. Then, any changes made to boost will be that much more effective. Ford threw pretty much all the bells and whistles at the new 5.8L, but it is the execution that sets the combination apart.

The first step was to increase displacement, taking the 5.4L to a full 5.8 liters, or 351 ci for those yet to embrace the metric system. Like the 5.0L 302, the 5.8L 351 displacement offered historical Blue Oval significance, especially for Cleveland, Midland, and Windsor Ford fanatics. The bore and stroke of the modern modular engine differs from those originals, but the shared displacement at least provides a link to the past. The extra displacement was achieved by increasing the bore of the 5.4L from 90.2 mm (3.55 inches) to 93.5 mm (3.68 inches). The already lengthy 105.8mm (4.165-inch) stroke remained unchanged. Given the restrictive bore center of the modular engine, the increase in bore size was only possible thanks to a new spray-bore process Ford calls Plasma Transfer Wire Arc, that replaced the iron cylinder liners with a ultra-thin (0.006-inch) cylinder coating.

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Inside the aluminum GT500 block, Ford modified the internals for the intended output. The increase in displacement was accompanied by an increase in the static compression ratio, too. The revised power output and attending cylinder pressure required a new (stronger) piston design. Mahle was given the nod to design forged slugs with the strength to withstand the elevated cylinder pressures and temperatures. The (just under) 3cc decrease in dish volume was combined with the (just over) 3mm increase in bore size to bump up the static compression ratio from 8.4:1 to 9.0:1. This should improve off-boost performance and efficiency. Minor revisions were made to the small end of the connecting rod and bearing material, as well as the overall balance of the forged-steel crankshaft (required from the change in piston weight).

To increase heat dissipation and piston life, the 5.8L is equipped with piston oil squirters. A great deal of research and development went into the design, placement, and flow of the squirters to ensure adequate and not excessive oil flow under all conditions. The 5.8L retained the Four-Valve cylinder heads with only minor revisions. The heads were treated to new Nimonic alloy exhaust valves equipped with Stellite rings on the seating surfaces. To better withstand the added pressure and heat generated by the 5.8L, the exhaust valve facing was also changed. To further enhance longevity, the 5.4L heads were also treated to an additional machining operation to improve coolant flow between the exhaust valves. The 5.8L aluminum block received a similar operation to route the coolant through the passage in the cylinder heads.

Unlike the 5.0L Coyote engine, the 5.8L does not require variable cam timing, and relies on the high-lift cams from the 5.4L Ford GT supercar. The Ford GT cams increase lift by 1.1 mm on the intake, and 1.4 mm on the exhaust over the GT500 cams. The GT heads and cams are combined with a blower upgrade from the M122 used on the previous GT500 to the 2.3L Eaton TVS.

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