Читать книгу Ford Coyote Engines - Jim Smart - Страница 8
ОглавлениеThe Coyote is fitted with an induction-hardened, fully counter-weighted, 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.
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’s induction-hardened forged steel eight-bolt crankshaft is fully counter-weighted and up to the task from 400 to 1,500 hp. It has the same dimensions as the 4.6L with 2.652-inch main journals and 2.086-inch rod journals. Ford stayed with this crank because it is time and race proven. It just doesn’t break.
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.
Although a lot of different markings have shown up on Coyote cranks, such as this DW, there appears to be little or no difference in these eight-bolt flange crankshafts. All are eight-bolt flange in forged steel with the same nuances. Even the BOSS crank isn’t much different from the standard crank. If you’re going to thrust horsepower above the 800 mark, consider the BOSS crank. Closely inspect any crank and have it tested by a trusted machine shop.
Here’s the M-6303-M50B 2012–2013 BOSS 302 crankshaft. This is a BOSS 302–specific forged steel crankshaft, which is a cut above the Coyote’s steel crank. What makes this racing specific is race-ready machining and balancing with chamfered oil holes and polished journals.
This is a stock 5.0L Coyote short-block with hypereutectic 11.0:1 pistons and powdered-metal rods. It is remarkable how well this engine endures in stock form under extreme abuse in the 400- to 600-hp range.
The Coyote’s steel crank is a class act with highly polished journals and chamfered oil holes. It is a remarkable piece, considering it is a production part and not a high-end racing part. There’s very little you have to do to this crank whether you’re building a stocker, weekend racer, or all-out full-time racer. Dimensions must be examined and documented along with a mock-up before the final build. Dynamic balancing is a must.
All Coyote cranks have this eight-hole flange, which is on a par with the 4.6L truck crank. This crank can withstand 400 to 1,500 hp. Some racers have pushed it close to 2,000 hp without failure.
This is the high-compression 11.0:1 flattop hypereutectic piston for naturally aspirated Coyotes. With this much compression, you are limited in terms of boost and nitrous. You want to be careful about how much boost and nitrous you apply to prevent engine damage.
“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.
Although the Coyote’s powdered-metal stock rod shares the 4.6L’s rod dimensions, it is not the same rod and cannot be interchanged. Although enthusiasts are spooked by the “powdered metal” nomenclature, in truth “powdered metal” is a high-tech forging process that’s actually stronger than classic I-beam connecting rods used in older pushrod engines.
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).
Do You Have Oil Cooling Jets?
It gets confusing because Ford eliminated oil cooling jets in production for a short time, and then brought them back into production for 2015–2016. Not all Coyote blocks have the oil cooling jet provision. And if you’re going to stuff H-beam rods into your Coyote, keep oil cooling jet clearances in mind. Not all rods and pistons clear. It is unknown why Ford dropped the oil cooling jets in production, aside from perhaps cost. As Ford stepped up the power for 2015, it became apparent that oil cooling jets needed to return, especially with high-boost turbo and supercharged applications.
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.
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.
