Typical of current Ford engines,...
Typical of current Ford engines, the beautifully cast Coyote front cover is a large, sprawling piece sealing the entire front of the engine. It's heavy and structural so belt tensioners and such can be bolted to it, and that means plenty of ribbing. The ribs make the NVH people happy, but increase cost and weight, and impede oil draining, so even this cover was an engineering battlefield for the Coyote team. Inside, the enclosed area has been kept large to improve engine ventilation and slough oil off the whirring timing chains. This was partially accomplished by keeping the core engine packaged rearward, leaving room for the longer oil pump, ventilation, and so on under this cover at the front. Check out those unused, reinforced bosses on the left branch. They seem poised for the tensioner and idler pulleys in a blower drive to us. The curved edge in the lower right in this photo is for the alternator.
Because a major mandate of the Coyote program was utilizing Ford's existing V-8 mass-production capabilities, and because 5.0 liters was considered the appropriate displacement, the jumping-off point for the Coyote was the closest existing engine, the Three-Valve 4.6 V-8.
There was no requirement to save anything of the 4.6 in the Coyote other than it must be suitable for production on the same machinery. As primary goals were the Coyote be stronger, more compact and powerful than the 4.6, it was a given that almost nothing from the 4.6 would carry over to the Four-Valve 5.0 TiVCT. Essentially nothing did, except the 4.6 bore spacing and its inherent limit on bore diameter.
To achieve the desired accessory-drive...
To achieve the desired accessory-drive belt path, the Coyote's water pump rotation was reversed and the thermostat housing was incorporated onto the pump casting. The O-ringed housing bolts to the round boss on the right of the pump, as seen here. The engineers say the coolant path through the engine is important, but what direction the flow takes is not. You might not think the water pump has much to do with the throttle body, but the reason the drive belt path needed attention was to package the center-mounted throttle body as low as possible.
Bore spacing is critical in the modular engine family-all modulars use 100mm (3.937-inch) bore spacing-because bore spacing and right bank leading are the major non-adjustable features of Ford's block machining line at the engine plant. In fact, bore spacing is likely the defining characteristic of the modular engines. They got the name "modular" because they were conceived in the '80s as a family of engines the assembly plant would sense as nearly identical and thereby allow rapid flexibility in their production. Thus, a modular could be a V or inline four-, six- or eight-cylinder engine, and any one of those engines could be built on Ford's engine lines with just a few hours of change-over time. In some cases similar engines could be built at the same time on the same line in random order, such as is done with 4.6 and 5.4.
Given all that, the new 5.0 was going to have a 100mm bore spacing and claim its place as the newest member of the modular family even though in nearly all other respects it is an all-new engine.
Of course, the Coyote team was as intent on giving its performance engine the maximum possible bore diameter. A large bore allows better breathing because it unshrouds the valves, plus it supports higher rpm operation because more of the displacement is in the bore and not the stroke so piston speed can be conserved.
Coyote water pumps use a phenolic...
Coyote water pumps use a phenolic impeller to eliminate rusting, and thus gradual cooling-system degradation. Coyote uses Ford's new environmentally friendlier organic-acid antifreeze, which is red. That coolant is now fed directly to the water pump from the radiator, rather than passing into the block as with previous modulars. The new path reduces cavitation and greatly lowers the water pump's drive requirements.
Therefore, the Coyote team turned to the pressed-in iron cylinder liners in the Coyote's aluminum block. The critical decision was to get the liner as thin as possible for the largest possible bore, but not so thin it would be weak. In the end, that measurement was 92.2 mm, or 3.263 inches. This is 2.0mm larger than the 4.6 bore, a dimension taken mainly out of the cylinder liner and not the block.
Stroke was driven by the compromises inherent in reaching the desired 5.0 displacement such as keeping the engine physically compact (low and narrow), moderating piston speed, leaving room for ring packaging and so on. The Coyote team elected to retain the 4.6's deck height, and a 92.8mm (3.653-inch) stroke was selected to reach 5.0 liters.
To put the 5.0's short-block architecture in perspective, here it is compared to the familiar 4. 6 and 5.4 modulars:
|Bore Spacing ||100.0 mm||(3.937 inch)||100.0 mm||(3.937 inch)||100.0 mm||(3.937 inch)|
|Bore||90.2 mm||(3.544 inch)||92.2 mm||(3.623 inch)||90.2 mm||(3.544 inch)|
|Stroke||90.0 mm||(3.537 inch)||92.8 mm||(3.653 inch)||105.8 mm||(4.165 inch)|
|Deck Height||227.0 mm||(8.937 inch)||227.0 mm||(8.937 inch)||256.0 mm||(10.079 inch)|
|Con Rod Length c-c||150.7 mm||(5.933 inch)||150.7 mm||(5.933 inch)||169.1 mm||(6.658 inch)|
|Rod-to-Stroke Ratio: ||1.67||1.62||1.60|
Packing the airflow of a NASCAR...
Packing the airflow of a NASCAR racing head in a compact package, the new Coyote cylinder head promises to re-write enthusiasts' Mustang GT expectations.
Note how there is an even 400cc increase in displacement with each engine, but how the 5.4 requires a taller and wider engine (deck height) to accomplish its increase over the 5.0. This is the tradeoff in being married to the 100mm bore spacing.
Keeping the same bore spacing also partially drives dimensions in the crankshaft and main bearings. Lowering friction is another major concern with the Coyote's 7,000-rpm redline, so the impetus was not to increase bearing diameters or widths. Existing 4.6 bearing sizes proved bulletproof and the Coyote crankshaft shares journal sizes with the 4.6 crank. In fact, the aluminum bearing shells are direct carryovers from the 4.6. No fancy tri-metal or copper bearings were required, so that was one less thing to re-invent.
Looking more like funnels...
Looking more like funnels than intake ports, this view hints at why the Coyote intake valves flow 4 percent better than their GT500 brothers. Naturally, all Coyote ports were made as vertical as possible within the production car limitations that rankle every hot rodder. "The exhaust port is a little low, it's at modular height," carped Adam Christian, but it still exceeds Ford's flow goals. Interestingly, the Coyote exhaust port doesn't quite flow as well as a GT500, but only because the Coyote uses a smaller exhaust valve to better package the combustion chamber. And if this intake port looks simple, it is. What you see is what you get: just two symmetrically round ports blended into an oval at the manifold parting flange. There are no asymmetries, swirl-inducing curves, or flow-inhibiting auxiliary throttles.
Adam Christian chose round...
Adam Christian chose round exhaust ports for the Coyote head, saying they are an especially good choice when exiting into header primaries that may curve up or down, as with the Coyote headers. Furthermore, previous oval modular exhaust ports pinch their flow into the tall axis of the port in curves, but were easier to blend into one passage near the valves. The Coyote's round ports require more design care in the blend and outlet, but outflow the Three-Valve's oval ports. The extensive surface cross-hatching facilitates metal flow during casting in the foundry. Head development was so fast and overlapped that the exhaust manifold was not finalized when Todd Brewer had to establish the exhaust port outlets. So he designed them to accept four 10mm exhaust studs at each port so opposing pairs could be chosen later depending on primary pipe layout and manufacturing concerns.
By using five casting cores,...
By using five casting cores, the Coyote team was able to excavate useless aluminum from otherwise inaccessible areas. These include under the oil galleys and camshaft journal bulkheads, plus a host of nooks and recesses. The Coyote ought to offer an improved center of gravity over previous Ford Four-Valves, and anything that helps unload the Mustang's front axle is a great thing.
Like the block's deck, the...
Like the block's deck, the Coyote head exhibits near perfect symmetry in bolt holes, cooling passages, and combustion chambers. The manifold section of the cross flow cooling system is visible as the noticeable step in the upper edge of the head's machined face. A large rectangular hole at the right, or front, of the head transfers the coolant to the crossover in the block. The machined arc below the coolant rectangle is a block-to-head oil passage for upper engine lube and VCT functions. Note how the intake ports aren't even visible in this angled view-they're nearly vertical!
From the looks of it, Ford...
From the looks of it, Ford had to make tough decisions in the Coyote combustion chamber but built a well-balanced design. It's is a little deep and the valves sunk a tad more than expected, but these are to separate the valves and pistons for increased TiVCT action. Ditto the slightly shrouded 37x31mm valve package; despite its crowded looks and compact exhaust valve the head flows like gangbusters, and still makes 11:1 compression with a flat top piston, and has variable cam timing to boot. This chamber is about airflow, with light quench area and no swirl or tumble. The small round pad between the exhaust valves is a locating pad used at the factory.
Because Four-Valve engines...
Because Four-Valve engines use such small valves, even at higher rpm the valvetrain is not particularly loaded. Thus, the Coyote team reached for Ford's "best practices" beehive valvesprings, valves, retainers, keepers and seals for their engine. All are good, proven parts and not exotic in any way. Excellent cylinder head cooling means these parts are lightly stressed.