Most Common Performance Fastener FAQs

To help you choose the ideal P1 Manufacturing hardware setup, we’ve gathered and answered the most common frequently asked questions (FAQs) performance engine builders face regarding critical engine fasteners.

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Q: What's the difference between hydrogen embrittlement and stress corrosion cracking, and how do they apply to H260 vs. P270?

A: Both hydrogen embrittlement and stress corrosion cracking can cause a high-strength fastener to crack under load, but they originate from two very different mechanisms. Hydrogen embrittlement is introduced during manufacturing. Tiny hydrogen atoms can enter the metal during processes such as acid cleaning, pickling, electroplating, or other surface treatments. If the hydrogen is not properly removed through baking, it can make hardened steels brittle and susceptible to delayed failure under load. This phenomenon primarily affects high-strength martensitic steels, such as the material used in H260, where hydrogen can be absorbed and migrate through the steel matrix.

The composition and austenitic crystal structure of P270, a nickel-based superalloy, make it highly resistant to hydrogen embrittlement. For all practical purposes, it is essentially immune to this failure mechanism and does not require the special processing precautions associated with plated high-strength steels.

Stress corrosion cracking (SCC) originates from the service environment rather than the manufacturing process. It occurs when a fastener is subjected to sustained tensile stress while simultaneously exposed to a corrosive environment. Over time, the combination of stress and corrosion can initiate and propagate cracks.

In our real-world experience, stress corrosion cracking is actually the most common brittle failure mechanism we encounter - not true hydrogen embrittlement. Because P270 is a nickel-based alloy with exceptional corrosion resistance, it is highly resistant to most forms of corrosion and is therefore essentially immune to stress corrosion cracking in the environments typically encountered in high-performance engine applications.

The good news is that stress corrosion cracking is relatively easy to prevent through proper handling and care of the fasteners. That care doesn't end after installation. Equally important is how the hardware is treated between rebuilds. A fastener sitting on a shelf exposed to moisture and air can still become susceptible to corrosion over time.

We recommend storing fasteners with a light coating of oil. The oil film acts as a barrier, sealing the metal from moisture and other corrosive elements that can contribute to stress corrosion cracking. Proper storage protects the hardware from the time it is manufactured, through storage, and until its next installation.

In summary: At P1, our manufacturing processes do not introduce hydrogen into the fastener, so hydrogen embrittlement is not a concern with the hardware we produce. The primary failure mechanism to guard against is stress corrosion cracking, and it is easily prevented through proper handling, installation, and storage. By following these simple practices, you can expect a long, reliable service life from both H260 and P270 fasteners.

Q: Can I just tighten my factory hardware tighter to get more clamping force?

A: No. Every material has a maximum "yield point." Tightening standard hardware past its designed limit will cause it to permanently deform and fail, losing its clamping force entirely. To safely increase clamping tension without shifting to a physically larger fastener diameter, you must upgrade to a higher material grade - such as moving from an entry-level E190 up to an S220 or P270.

Q: When my engine pushes gaskets, should I step up to a larger fastener diameter or upgrade to a stronger material grade?

A: Upgrade the material grade first to avoid complex, high-risk machining. Modifying a block and cylinder head to accept a larger fastener diameter requires precise drilling and tapping, which risks ruining the block or breaking into water jackets. Upgrading the material grade - such as swapping a 7/16” E190 stud for an ultra-high-strength 7/16” P270 stud - drops directly into the factory holes while instantly delivering a massive jump in clamping force with zero modifications.

Q: How do the math and physics change when I combine both a physical size upgrade and a material grade upgrade?

A: The gains compound exponentially. Clamping capacity relies on the fastener's cross-sectional area, which scales with the radius squared (A = 𝞹r²). Simply increasing size from a 7/16” to a 1/2” diameter yields a 40% increase in clamping force due to geometry alone. However, when you combine a larger size with a premium alloy - like upgrading from a 7/16” E190 stud to a 1/2” S220 stud - the cross-sectional growth and higher material yield strengths multiply to deliver a staggering 53% increase in total clamping capability. Read Our Clamping Force Tech Guide. 

Q: Are P1 high-performance fasteners reusable, or are they one-time-use "Torque-to-Yield" (TTY)?

A: P1 fasteners are 100% reusable because they are engineered to act as ultra-strong mechanical springs within their elastic limit. Unlike factory TTY bolts, which permanently deform and must be discarded after a single use, P1 materials (E190, S220, H260, P270) safely return to their original length when untorqued. However, reusability depends entirely on bolt stretch. If a fastener takes a "permanent set" - meaning it has permanently stretched by 0.001" or more beyond its original baseline length - the metal has entered plastic deformation and must be replaced immediately.

Q: Why does P1 recommend hand-tightening studs into the engine block instead of torquing them?

A: Cylinder head and main studs should be installed by hand only until the stud bottoms or thread run-out occurs. You can use a hex key with light force only during the final seating. Torquing a stud directly into the block using heavy tools loads it unevenly and induces structural shear stress. By keeping the stud hand-snug in the block and applying torque exclusively to the top nut, you ensure that the forces acting on the stud are pure vertical tension, maximizing clamp load accuracy.

Q: Should I install my fasteners using standard engine oil, or do I need a specialized assembly lubricant?

A: You must use TorquePoint Fastener Assembly Lube (Learn More Here). Up to 90% of torque wrench input is consumed just overcoming friction. Engine oil and generic grease lack consistency, leading to "torque scatter" - where some bolts clamp tighter than others. TorquePoint lube stabilizes friction, ensuring that a specific torque setting perfectly translates into the designed preload. 

Crucial Note: Never lubricate P1 washers. Washers must be clean, free of rust-preventative coatings, and completely dry during installation so they do not rotate during the torque procedure. Lube is applied only to the threads and the nut's bottom bearing surface. Carefully review the installation guide for your specific fastener kit Here.

Q: Is it safer to install connecting rod bolts using a torque wrench or a stretch gauge?

A: Whenever physically possible, always use a stretch gauge. A torque wrench is an indirect measurement tool - it guesses the bolt's tension based on how hard it is to turn. If there is a tiny burr on a thread or an uneven patch of lube, your torque wrench will click early, leaving you with insufficient clamping load. A stretch gauge bypasses friction entirely by directly measuring the physical elongation of the bolt shank. Direct stretch is the absolute most accurate indicator of true preload.

Q: Do I need to clean P1 fasteners out of the box, or can I install them as they are shipped?

A: You must perform a specific cleaning procedure before installation. First, remove the washers from their packaging and completely clean off the rust-preventative coating from all faces using a petroleum-based solvent, placing them on a clean rag. For the studs and nuts, place them on a clean shop rag and clean the threads as required, but do not unnecessarily remove the factory rust-preventative coating from the main body of the hardware. Always ensure your engine block holes are thoroughly cleaned of all debris before test-fitting.

Q: Does upgrading to high-strength P1 studs distort my engine's bearing bores or cylinders?

A: Yes, and this is actually proof that the fasteners are doing their job. Because P1 materials like S220 and H260 exert vastly superior clamping loads compared to weak factory hardware, they will structurally pull and slightly distort the engine block's main bearing tunnels or cylinder walls. To prevent bearing failure or poor piston ring sealing, it is recommended to have your machinist hone the cylinders and line-bore the mains with the P1 hardware installed and fully torqued to operational specifications.

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