Brian Crower LightWeight 4340 Billet Crankshaft – Nissan SR20DE / SR20DET | 91mm Stroker | BC5209LW

This is a 91mm stroker crankshaft — it increases the SR20DE/DET stroke from 86.4mm (stock) to 91mm, raising displacement to approximately 2,113cc (2.11L). A complete rotating assembly specification — rod length, piston compression height, deck clearance — from an experienced SR20 engine builder is required before ordering.

Brian Crower BC5209LW LightWeight 4340 billet crankshaft for the Nissan SR20DE and SR20DET. 91mm stroke, precision LightWeight counterweight machining. 20 lbs. Ships fast across Canada and the US.

LightWeight Billet — Reduced Rotating Inertia

Brian Crower’s LightWeight designation indicates precision material removal from counterweight faces and non-structural areas of the crankshaft beyond what a standard billet crank receives. Counterweights are knife-edged and profiled to minimise windage losses at high RPM. The result is a lower rotating assembly inertia than a standard billet crank of the same stroke — improving throttle response, reducing the energy required to rev the engine, and allowing a higher effective RPM ceiling. On a 4-cylinder SR20 build where high RPM is often part of the power strategy, LightWeight specification is appropriate. The crank is cross-drilled for optimised oil delivery to rod and main journals.

4340 Billet Construction

The BC5209LW is machined from a single piece of 4340 chromoly steel billet bar stock — providing consistent, isotropic grain structure, superior tensile strength, and fatigue resistance compared to OEM cast or forged crankshafts. The OEM SR20DET crankshaft is a capable unit at moderate power, but at 500–700+ hp on a built stroker motor, billet quality ensures the crankshaft is not the limiting factor in the rotating assembly’s durability.

91mm Stroker — SR20 Displacement

The OEM Nissan SR20DET and SR20DE use an 86.4mm stroke with an 86mm bore for 1,998cc (2.0L) of displacement. Increasing stroke to 91mm raises displacement to approximately 2,113cc (2.11L) — a 4.6mm stroke increase that meaningfully adds torque across the RPM range. The additional displacement is particularly valuable in turbocharged SR20 builds running large single-turbo setups, where the extra cubic centimetres improve spool characteristics and allow the engine to generate more torque at lower boost pressures compared to a stock-stroke engine at the same power target. A complete rotating assembly specification — crank stroke, connecting rod center-to-center length, piston compression height, and deck clearance — must be confirmed by your engine builder before parts are ordered.

SR20DE and SR20DET — Shared Architecture

The SR20DE (naturally aspirated) and SR20DET (turbocharged) share the same block architecture and crankshaft dimensions, making the BC5209LW applicable to both. SR20DET applications dominate at this performance and price level — the turbocharged S-chassis Silvia, 180SX, 200SX, and Pulsar GTI-R are the primary targets for an SR20 stroker build. SR20DE-based builds are less common but relevant for high-revving NA SR builds where the LightWeight billet crank’s reduced rotating inertia is particularly advantageous.

S-Chassis Stroker Context

A 91mm stroker SR20DET in an S13, S14, or S15 chassis is a serious performance combination. With appropriate connecting rods, pistons, a built head with performance camshafts, a large single turbocharger, and supporting fuel and engine management, a stroked SR20 is capable of 500–700+ hp in a package that retains the S-chassis’s lightweight, balanced handling characteristics. The stroker crank is the foundation of this combination — everything else in the rotating assembly is specified around it.

Required Rotating Assembly Components

Confirm with your engine builder before ordering:

• Connecting rods — must be specified for the 91mm stroke (correct center-to-center length) and the SR20’s 45mm rod journal big-end bore
• Pistons — must be specified for the correct compression height to achieve the desired deck clearance with the selected rod length and 91mm stroke
• Rod bearings — source premium aftermarket 45mm bearings (King, ACL, Clevite/Mahle) to the correct oil clearance specification; do not reuse OEM bearings
• Main bearings — standard SR20 main bearing size; confirm with Brian Crower
• Balancing — balance the complete rotating assembly as a set after sourcing all components

91mm stroker — complete rotating assembly spec required before ordering. Professional engine building and precision machining required. Balance complete rotating assembly before installation. Confirm all journal clearances before assembly. Do not reuse OEM rod or main bearings.

Specifications

• Brand: Brian Crower
• Part Number: BC5209LW
• Type: LightWeight 4340 billet crankshaft
• Application: Nissan SR20DE / SR20DET
• Stroke: 91mm (stock: 86.4mm)
• Rod Journal Diameter: 45mm (standard SR20)
• Material: 4340 chromoly steel billet
• Weight: 20 lbs