It has been ten years since Ford introduced the Coyote engine, which is the evolutionary successor to the 4.6 and 5.4 liter "modular" engines. Undoubtedly, Coyote's sturdy architecture and impressive performance have enhanced Mustang's popularity, and the powerful 5.0L mill has become a popular alternative to classic trucks, hot rods and kit cars.
An important step in preparing Coyote to handle the increased power is to replace the OEM factory head bolts-yielding to the design torque.
In the form of inventory, the engine has proven to be very reliable. However, given the preference of performance enthusiasts for increased power, in many cases, factory fasteners are simply not up to the task. All modern engines are assembled using torque yield (TTY) bolts. They are technically produced by design and are not intended to deal with significant increases in combustion pressure and load. More importantly, when they are produced, they should not be reused.
ARP head bolts are designed to provide greater clamping load, have additional safety margins, and can be reused (unlike TTY head bolts).
The ARP engineering team literally "dissected" Coyote and rigorously tested every key fastener used to assemble the engine. It should be pointed out that ARP's huge internal laboratory contains a large number of equipment, which can evaluate the strength, load capacity and fatigue life of any fastener, and perform computer-controlled cyclic testing. Subsequently, ARP developed improved fasteners for all important tasks and listed them all in the handy Coyote product guide.
4 Valve DOHC Coyote cylinder head is very complex and can benefit from stronger fasteners in many areas.
As you suspect, increasing the combustion pressure through a power adder or higher compression piston requires replacing stock TTY (torque yield) head bolts with high-strength studs to ensure proper sealing and prevent head gasket failure. ARP's Coyote replacement head studs are made of proprietary ARP2000® material and have a nominal tensile strength of 220,000 psi. They can be used in M11 and M12 applications.
It should be noted that this is not only because ARP uses high-quality materials, but also special manufacturing operations, such as internal heat treatment of studs in a special frame to achieve balanced penetration and heat-treated rolled threads, which helps To improve durability-for example, fatigue life increased by 10 times.
By using ARP heat-treated 8740 chromium-molybdenum main bolts, the bottom end of Coyote can be easily strengthened. Its nominal pressure rating is 190,000 psi, which is much better than factory TTY bolts. The main cap kit includes four studs per cap and two side bolts to provide rock-solid support. Also includes parallel ground flat washers and 12-point nuts.
One fastener that is often overlooked is the key bolt that secures the harmonic damper. ARP has developed a special heat-treated 8740 chromium-molybdenum alloy bolt with a large 12-point bolt head, which can be easily rotated by hand to set the timing without having to worry about rounding the bolt head like OEM hex bolts. It is equipped with a ¼ inch thick large area washer to better distribute the clamping force.
One of Coyote's strengths is its DOHC configuration, and ARP engineers have paid special attention to developing excellent alternatives to factory cam phasers, cam sprockets and cam tower bolts that help maintain accurate cam timing.
ARP does not list a separate exhaust kit for Coyote in its catalog. no problem. Use an accessory stud kit (P/N 400-8036) containing 16 polished stainless steel M10 studs (1.25/1.25 pitch), 12-point nuts and M10 washers. They have a length of 1.900 inches and are suitable for most header flanges, but other lengths of stud (and metric bolt) kits are also available. It is worth noting that ARP uses a proprietary alloy with a nominal tensile strength of 180,000 psi, which is a full 20% stronger than Grade 8 hardware.
These polished stainless steel and similarly graded black anodized 8740 chrome-molybdenum alloy fasteners are available in a variety of sizes and lengths (SAE fine and coarse threads, from #10-32 x ½ inches to ½ inches x 6 inches) plus Metric M6 to M12, 12-point or hexagonal head can be selected. They come in handy 5 piece packs. Add a series of "bulk" studs of various sizes, and you can secure most things in the engine compartment.
ARP's main stud kit helps increase clamping force to help prevent crankshaft bending and cover "walking".
When you increase the power of Coyote, it makes sense to ensure that your drivetrain benefits from the extra safety of ARP's special 8740 chrome molybdenum flywheel bolts. They have a large diameter (3/4 inch wrench) 12-point head, distribute clamping loads better than ordinary bolts, and have a larger shank diameter than stock to increase strength and improve flywheel alignment.
The Coyote exterior has important fastener upgrades, such as improved flywheel (middle) and damper bolts (right). Specially designed flywheel bolts provide improved positioning and better load distribution, while ARP’s unique damper bolt has an extended 12-point head for easy turning of the engine by hand.
Most importantly, the use of high-quality ARP fasteners to manufacture engines can provide you with greater clamping force than OEM hardware, additional safety margins, and the ability to reuse them (unlike factory TTY bolts). This is clearly a long-term investment in reliability.
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