AR8720 – Nissan SR20DE(T) ARP Main Studs

For the engineer, the tuner, and the purist building a Nissan SR20DE, SR20DET, or SR20VE to withstand the relentless demands of forced induction and high-RPM operation, the factory main bearing cap fasteners represent a critical point of failure. The ARP 8720 (202-5402) Main Stud Kit is not merely an upgrade; it is a foundational re-engineering of the engine’s core structure. Designed to supplant the marginal tensile strength of original equipment bolts, this kit delivers an exponential increase in clamping force, ensuring the crankshaft remains perfectly aligned and the main bearing caps remain immovable under extreme cylinder pressures. This is the definitive insurance policy for your SR20’s bottom end, transforming it from a potential weakness into an undeniable strength.

Engineering Superiority: The ARP 8720 Design Philosophy

The factory main bolts on the Nissan SR20 engine are adequate for stock power levels but become a liability in performance applications. Under high boost and torque, these bolts can stretch, allowing minute but destructive movement of the main bearing caps. This movement accelerates bearing wear, can lead to crankshaft walk, and is a primary contributor to catastrophic engine failure. The ARP 8720 kit addresses this with a material and design solution rooted in aerospace-grade engineering.

Material and Manufacturing Precision

Each stud in the ARP 8720 kit is machined from ARP 8740 Chrome Moly steel, a material selected for its exceptional strength-to-weight ratio and phenomenal fatigue resistance. This alloy is heat-treated using ARP’s proprietary process to achieve a 190,000 psi tensile strength, far surpassing the capability of any OEM bolt. The studs are then roll-threaded, a cold-forming process that compresses the grain structure of the metal along the thread roots. This creates threads that are stronger, smoother, and more resistant to stress concentrations than cut threads, providing a consistent and reliable clamping load cycle after cycle.

Tangible Performance Benefits for the SR20 Platform

• Unmatched Clamping Force: The stud-and-nut configuration, coupled with the ultra-high tensile material, applies a vastly more uniform and powerful clamping load across the main bearing cap and engine block. This eliminates cap fretting and maintains perfect bearing crush.
• Eliminates Bolt Stretch & Torque Loss: Unlike tapered OEM bolts that can yield and stretch permanently, ARP studs behave elastically. They return to their original length after tensioning, ensuring the installed torque (and thus clamping force) remains constant.
• Enhanced Crankshaft Stability: By securing the main caps with absolute rigidity, crankshaft deflection is minimized. This promotes optimal oil clearance control, reduces bearing fatigue, and contributes to overall engine longevity and power delivery.
• Simplified, Precision Assembly: Studs guide the main caps into perfect alignment during engine assembly, making the process easier and more accurate. The use of separate nuts also allows for the use of a torque wrench in more accessible positions.
• Foundation for Extreme Power: This kit is considered mandatory for any SR20DET build targeting over 400whp or sustained high-RPM track use. It is the bedrock upon which reliable, big-power builds are constructed.

Vehicle Fitment & Application Details

The ARP 8720 Main Stud Kit is engineered as a direct, no-modification replacement for the factory main bearing cap fasteners in a specific range of legendary Nissan engines. Correct application is critical for fit and function.

Primary Application: This kit is designed for the Nissan SR20DE(T) 2.0L 4-cylinder engine with a 5-main-bearing crankshaft. This covers the vast majority of SR20 variants found in popular performance vehicles.

Specific Vehicle Fitment Includes:

• Nissan Silvia S13, S14, S15 (with SR20DET)
• Nissan 180SX / 200SX (with SR20DET)
• Nissan Bluebird (U12) SSS Attesa (with SR20DET)
• Nissan Pulsar GTI-R (SR20DET)
• Nissan X-Trail (T30) (with SR20DE)
• Various Nissan Serena and Vanette models equipped with the SR20 engine

Important Note: This kit is specifically for the 5-main-cap SR20. It does not fit the earlier CA18DET engine or other non-SR20 Nissan engines. Always verify your engine’s main cap configuration before purchase.

Technical Specifications & Kit Contents

The ARP 8720 kit is complete, providing every component needed for a professional installation. Understanding the specifications is key to appreciating the quality on offer.

The Final Word on SR20 Bottom-End Integrity

Investing in forged internals, a performance turbo, and expert tuning is an exercise in futility if the engine block itself cannot contain the forces generated. The ARP 8720 Main Stud Kit fortifies the very foundation of the Nissan SR20 engine. It is a precision-machined component that offers no performance gain on a dyno sheet but provides immeasurable gains in reliability, durability, and confidence. For a deeper technical understanding of why studs are fundamentally superior to bolts in high-stress applications, consider the principles discussed in this analysis of engine fastener technology. When building an SR20 for performance, the choice is binary: accept the OEM’s design limitations or engineer beyond them. The ARP 8720 represents the latter—the unequivocal standard for a locked-down, unyielding bottom end.