Mazworx RB25 Short Block Stage 2.5

The Mazworx RB25 Short Block Stage 2.5 is expertly built to support power outputs ranging from 600 to 1,000 horsepower, making it suitable for both Series 2 and NEO Nissan RB engines. Designed for higher-horsepower applications, the Stage 2.5 combines extensive block machining, precision balancing and premium internal components to provide a strong and reliable foundation for demanding RB engine builds.

Comprehensive Labor and Assembly Process

• Complete disassembly of the short block.
• Thorough hot tank cleaning and degreasing.
• Sandblasting followed by painting of the iron block for corrosion protection.
• Machining for threaded oil port plugs.
• Machining for threaded freeze plugs.
• RB26 oil groove machining.
• Machining to accommodate RB26 head studs.
• Inline block resurfacing to ensure precise mating surfaces.
• Resizing of cylinder bores using a torque plate for accuracy.
• Precision honing of the line bore.
• Installation of a Mazworx oil pump collar onto the crankshaft.
• Cleaning, inspection, polishing and balancing of the crankshaft.
• Final assembly of the short block with high-performance components.

High-Quality Performance Parts

• Custom HD CP pistons, 86.5mm with a 9:1 compression ratio.
• Upgraded 9310 wrist pins with 0.250″ wall thickness and 22mm diameter.
• BC ProH625+ connecting rods with 22mm wrist pins.
• ACL RB26 race bearings designed for high-performance applications.
• ARP main studs for secure main cap retention.
• Mazworx RB oil pump collar.
• Mazworx threaded and O-ring sealed small plugs for improved sealing and reliability.
• Mazworx threaded and O-ring sealed freeze plug kit for secure coolant sealing.

The Stage 2.5 short block provides an upgraded foundation for RB25 builds targeting up to 1,000 horsepower. With heavy-duty forged internals, extensive block preparation and precision machining throughout, it is built for high-output applications where strength, consistency and reliability are essential.

Note: Customer must supply a core short block.