Spool Nissan RB25/6 - 2.8L EN40B Stroker Crankshaft

Spool Nissan RB25 / RB26 – RB28 EN40B Billet Stroker Crankshaft

The Spool EN40B RB28 stroker crankshaft is engineered for Nissan RB25 and RB26 builds where increased capacity, torque, and extreme durability are required for high-boost and high-RPM applications.

Using a 77.7 mm stroke, this crankshaft increases displacement to approximately 2.8 litres, delivering a substantial improvement in torque, response, and overall engine performance compared to the factory crankshaft.

Why EN40B?

EN40B is a nickel-chromium-molybdenum alloy steel widely used in high-end motorsport and aerospace applications due to its outstanding fatigue resistance and core strength.

When nitrided, EN40B develops an exceptionally hard wear surface while maintaining a tough, ductile core—making it ideal for engines subjected to:

• High cylinder pressure

• Sustained high RPM

• Aggressive boost and ignition strategies

For serious RB builds, EN40B provides a clear step up in long-term reliability over traditional crankshaft materials.

True Billet Construction

The Spool RB28 EN40B crankshaft is a true billet crankshaft, precision CNC-machined from solid EN40B core stock.

This is not a cast or forged blank.

Manufacturing process:

1. CNC-machined from EN40B billet core stock

2. Heat treated

3. Precision nitrided for maximum surface hardness and wear resistance

4. Final ground and fully balanced

The result is a crankshaft with exceptional dimensional accuracy, torsional strength, and fatigue life.

Performance Benefits

Increasing stroke to 77.7 mm delivers meaningful gains in usable power across the rev range:

• Significant increases in low and mid-range torque

• Earlier turbo spool and improved throttle response

• Increased peak power potential

• Stronger acceleration and improved drivability

These benefits make the RB28 stroker combination ideal for street, drag, roll racing, and circuit applications using medium to large-frame turbochargers.

Crankshaft Specifications

• Application: Nissan RB25 & RB26

• Capacity: RB28 configuration

• Stroke: 77.7 mm

• Material: EN40B Billet Steel

• Fully Counterweighted

• Precision Nitrided

• Fully Balanced

• Designed for High Boost & High RPM Use

EN40B vs 4340 – Crankshaft Material Comparison

Summary:
4340 billet steel is a proven and reliable crankshaft material for many RB builds.
EN40B is a premium upgrade, selected for RB25 and RB26 engines operating at extreme power levels, sustained high RPM, and aggressive boost where fatigue resistance and long-term reliability are critical.