Spool RB25 - 2.8L Extreme Stroker Kit with Custom CP Pistons

Spool Nissan RB25 / RB26 Extreme 2.8L Stroker Kit

The Spool Extreme 2.8 Litre stroker kit for Nissan RB25 and RB26 engines is engineered for serious high-power applications where strength, durability, and torque delivery are critical.

At the core of this kit is the Spool EN40B billet RB28 stroker crankshaft, combined with Drag Pro forged connecting rods and CP-Carrillo custom pistons, creating an uncompromising bottom-end solution for extreme boost and high RPM use.

Kit Includes

• Spool EN40B Billet RB28 Stroker Crankshaft
  77.7 mm stroke
  True billet construction, CNC-machined from EN40B core stock
  Precision nitrided, final ground, and fully balanced

• Spool Drag Pro I-Beam Forged Connecting Rods
  Supplied with ARP L19 bolts as standard
  Downgrade option available: ARP 2000 bolts or H-Beam Conrods with different bolt options.

• CP-Carrillo Custom Pistons
  Custom manufactured to suit RB25 and RB26 applications
  Available in multiple bore sizes and compression ratios
  Supplied complete with rings, pins, and locks
  Lead time: approximately 5–8 weeks

• 300M Tool Steel Gudgeon Pins
  0.250" diameter supplied as standard
  Downgrade options available for lower power applications

Performance Benefits

Increasing stroke to 77.7 mm raises displacement to approximately 2.8 litres, delivering significant gains across the usable RPM range:

• Major improvements in low and mid-range torque

• Earlier turbo spool and improved throttle response

• Increased peak power capability

• Designed to handle extreme cylinder pressure and RPM

This combination is ideally suited to large-frame turbochargers, drag racing, roll racing, and high-end street builds where reliability at extreme power levels is non-negotiable.

Designed for Extreme RB Builds

Every component in the Extreme 2.8L stroker kit has been selected to support:

• High boost pressure

• Aggressive tuning strategies

• Sustained high RPM operation

• Long-term durability under extreme load

This is a no-compromise RB bottom-end package, built for customers who want maximum strength with flexibility to tailor components based on power goals.

Important Fitment Note

Note: Depending on block casting and assembly tolerances, minor conrod-to-block clearancing may be required during installation.

EN40B vs 4340 – Crankshaft Material Comparison

Summary:
4340 billet steel remains an excellent choice for many high-performance RB25 and RB26 builds.
EN40B is a premium upgrade, selected for engines operating at extreme power levels, high boost, and sustained high RPM where fatigue resistance and long-term reliability are critical.

Available options

• Piston Diameter: +0.5mm; +1mm; STD (Special Order)
• Pin Upgrade: 300M .250"; 9310 .250"; No Upgrade
• Conrod Option: Spool Drag Pro I-Beam ARP L19 7/16 Bolt; Spool Drag Pro I-Beam ARP2000 7/16 Bolt; Spool H-Beam ARP CA625 3/8 Bolt; Spool H-Beam ARP L19 3/8 Bolt; Spool H-Beam ARP2000 3/8 Bolt

Engine build fitment

RB25. Match the selected dimensions, engine generation and rotating assembly specification before machining or assembly.

Installation and BBT workshop support

Confirm block and head configuration, finished bore size, bearing clearances, compression ratio and crank trigger compatibility. Block clearancing and rotating assembly balancing may be required.

Built by Boost & Tune is an authorised Spool Imports dealer and can assist with component selection, engine assembly and tuning requirements for your build.