The Coyote is fitted with an induction-hardened, fully counterweighted, forged-steel crankshaft that’s virtually indestructible, featuring an eight-hole flange. Team Coyote decided to stay with the 4.6L engine’s main and rod journal dimensions because they have been a proven success in nearly two decades of service in every application imaginable. Moreover, aluminum bearings were borrowed directly from the 4.6L engine instead of opting for tri-metal bearings. Aluminum main and rod bearings work just as well as tri-metal bearings and without the excessive cost and weight involved.
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The Coyote engine shares the same connecting rod dimensions with the 4.6L engine at 5.933 inches center to center, yet it is not the same rod according to Ford. It is a much stronger rod with 12-point bolt heads. The rod ratio is 1.62:1, allowing for generous dwell time at each end of the bore. The Coyote’s powdered-metal cracked rod is a sintered-metal I-beam piece engineered for extreme street and weekend race duty. Although “powdered metal” sounds lackluster compared to the word “forged” it is a high-tech form of alloy metal forging that produces a stronger connecting rod than a traditional forged piece. However, the cracked powdered-metal rod isn’t up to the severe hammering of supercharging and nitrous oxide. If your goal is 600 to 1,000 hp, you need to consider a good aftermarket Manley or Oliver rod.
If you’re planning a supercharger or nitrous induction, Manley or Eagle H-beams or Oliver I-beams are a must rather than using the stock rod. The stock rod takes a lot of punishment and does it to 7,000 rpm. However, it is pushing your luck to go with anything less than a heavy-duty forged-steel I-beam or H-beam connecting rod if you’re going to push it above 600 to 800 hp.
The Coyote is fitted with lightweight hypereutectic pistons with coated skirts for reduced friction and wear. There’s also less piston noise on cold start. Ford engineers weighed the benefits of forged versus hypereutectic and hypereutectic won for its weight and expansion properties. Forged pistons are loose and noisy when they are cold, which generated plenty of complaints with 4.6L and 5.4L engines. In fact, 4.6L/5.4L enthusiasts became extremely concerned about cold-piston noise in Modulars even though it really is nothing to worry about.
“Hypereutectic” piston is just a fancy name for “high-silicon-cast” piston. It takes more abuse than a cast piston and doesn’t have the drawbacks and weight penalty of a forged piston. Hypereutectic pistons run quieter because you can run tighter tolerances without consequence. They tolerate the extremes of street and weekend race duty while offering durability. However, if you intend to supercharge or go nitrous, you’re better off with a forged and coated piston for best results.
Another reason Ford opted for a hypereutectic piston is oil cooling jets that keep the pistons considerably cooler, which improves piston life. This approach also allows for faster warm up because oil is in direct contact with one of the hottest parts of the engine right from the start. Ford engineers have proved that crankshaft journals run roughly 25 degrees F cooler with the oil jets, which enables this engine to operate on 87 octane fuel and survive (though 91 octane is optimum).
Most important to remember is clearance issues. Heavy-duty I-beam and H-beam connecting rods may or may not clear the tight confines of the Coyote block. You must first do a mock-up and rollover to make sure everything clears by at least .060 to .100 inch throughout 360 degrees of crank rotation with all rods and pistons (but without rings) installed. Pay close attention to piston skirt to crank counterweight clearances, which can get very tight and are the reason the Coyote doesn’t accept any more than a 3.649-inch (92.5 mm) stroke.
Room for Improvement?
So what can you do with a Coyote bottom end to make it even more durable than it already is? Ford’s factory steel-forged induction-hardened eight-bolt crankshaft is a masterpiece of engineering. It is virtually indestructible and can take upwards of 1,500 to 2,000 hp. All the Coyote crank really needs is dynamic balancing when you fit it with aftermarket connecting rods and forged pistons. Chamfering oil holes at the journals improves lubrication, and micropolishing journals improves oil control, but you don’t even need that. Ford produces an outstanding piece right out of the box.
You have the option of going to the BOSS 302 crank (M-6303-M50B), rods, and forged pistons (M-6100-M50BR as piston/ rod assembly) if you’re lacking confidence in the factory steel crank. These items are available off the shelf from Ford Performance Racing Parts. Suffice it to say the Eagle, Manley, or Oliver rod coupled with a Manley, Mahle, or Diamond forged piston will get the job done.
Manley’s Platinum Series forged pistons are a good choice thanks to 2618 aluminum alloy, 9310 steel alloy wrist pins, and coated skirts that offer stability and a more user-friendly skirt to cylinder wall relationship. Total Seal piston rings are a Manley exclusive and an industry standard. And when the need warrants, Manley will make you a custom piston. Manley offers at least 16 off-the-shelf pistons in 9.0, 10.0, and 11.0:1 compression ratios. Bore sizes are 3.630, 3.635, 3.640, and 3.700 inches for the 5.933-inch connecting rod and 3.650-inch stroke. Compression height on all is 1.165 inches. Standard and Extreme Duty versions are available.
The most common aftermarket performance connecting rods come from Manley and Eagle Specialties, 5.933 inches center to center. The 4340 steel H-beam rod is available in most kits and the Ford Performance and Roush Aluminator crate engines. These rods are shot-peened, stress relieved, Magnafluxed, heat treated, and weight matched to +/–1.5 grams. And finally, they are fitted with 3/8-inch ARP cap screws. They are rated at more than 700 hp with the standard ARP 8740 cap screws and more than 750 hp with ARP 2000 bolts.
The 4340/330M aircraft-grade steel Pro Series I-beam rod from Manley is machined to yield the lightest-weight rod possible from the forging. When machining is complete, Manley shot-peens these guys, Magnafluxes them, and fits them with 7/16-inch ARP 2000 cap screws. This process makes these rods good to more than 900 hp for road racing and more than 1,200 hp for drag racing.
Oliver Racing Products has two 5.933-inch rods for the Coyote, the Standard Light and the Ultra Light. The Standard Light connecting rod is a heavy-duty rod designed for weekday driving and weekend racing. The Oliver Ultra Light is an extreme high-performance connecting rod for high RPM use in the 8,500-rpm range. This is the rod you go racing with. It is lighter and stronger than the Standard Light.
Make Mine a Flat-Plane
It’s hard to find anyone in the performance industry who isn’t talking about the 5.2L flat-plane crank Voodoo Coyote cousin in the Shelby GT350. The Voodoo is a rapid departure from the conventional V-8 mindset thanks to its flat-plane crank where rod journals are spaced 180 degrees apart instead of the more routine 90 degrees. The flat-plane crank is what gives the 5.2L engine a more buzzy European sound.
The downside to a flat-plane crank is the absence of the counterweight balancing that you see with a 90-degree cross-plane crankshaft; this creates potential vibration issues not seen with a 90-degree. Ford has managed to tune vibration out with a crankshaft-mounted dampener system. The flat-plane crank 5.2L engine nearly didn’t make production due to these vibration issues.
It doesn’t take a long look at the 5.2L crank to see what’s missing: counterweights that add weight and mass to a crankshaft. A lighter crank spins quickly and with more fury because it enables you to get into the power band right away. The upside to counterweights is smoothness; the downside is weight. This is why Ford decided to take a crack at the flat-plane crank. Flat-plane technology puts the 5.2L heads and shoulders above anything else from Detroit. As with the steel Coyote crank, the Voodoo crank doesn’t have an aftermarket replacement because it isn’t necessary. The factory crank is as good as it gets. Ford Performance Racing Parts will have a Voodoo flat-plane crankshaft available by the time this book hits the shelves.
Written by Jim Smart and Posted with Permission of CarTechBooks