Brian Crower 4340 Billet Crankshaft – Nissan SR20DE / SR20DET | 91mm Stroker | BC5209

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 BC5209 4340 billet crankshaft for the Nissan SR20DE and SR20DET. 91mm stroke, standard billet construction (non-LightWeight). Ships fast across Canada and the US.

BC5209 vs. BC5209LW — Standard vs. LightWeight

Brian Crower offers two 4340 billet SR20 crankshafts at the 91mm stroke: the BC5209 (this crank) and the BC5209LW (LightWeight). Both use the same 4340 billet material and 91mm stroke. The LightWeight version undergoes additional precision material removal from counterweight faces — knife-edging, profiling, and windage reduction machining — to reduce rotating mass and inertia for improved high-RPM response. The BC5209LW is priced higher and is specified for builds targeting maximum RPM ceiling and rotating assembly response. The BC5209 is the correct choice for builds where billet material quality and stroke are the primary upgrade objectives and maximum counterweight mass reduction is not part of the specification. Both cranks use the standard SR20 45mm rod journal diameter.

4340 Billet Construction

The BC5209 is machined from a single piece of 4340 chromoly steel billet bar stock, providing consistent grain structure, superior tensile strength, and fatigue resistance compared to OEM cast or forged crankshafts. At 500–700+ hp on a built stroker SR20DET, billet construction removes the crankshaft from the list of potential rotating assembly failure points. The OEM SR20DET crankshaft is a capable unit at moderate power but is not designed for the sustained high-torque loading of a large single-turbo SR20 at serious boost levels.

91mm Stroker — SR20 Displacement

The OEM SR20DE and SR20DET use an 86.4mm stroke with an 86mm bore for 1,998cc (2.0L). Increasing stroke to 91mm raises displacement to approximately 2,113cc (2.11L) — a 4.6mm stroke increase that adds torque across the RPM range and improves spool characteristics on large single-turbo setups. The additional displacement allows the engine to generate more torque at lower boost pressures compared to a stock-stroke motor at the same peak power target, reducing heat load and improving drivability. A complete rotating assembly specification from an experienced SR20 engine builder is required before ordering — rod length, piston compression height, and deck clearance must all be calculated around the 91mm stroke.

SR20DE and SR20DET — S-Chassis Applications

The SR20DE (naturally aspirated) and SR20DET (turbocharged) share the same block architecture and crankshaft dimensions. SR20DET applications dominate at this performance level — the S13, S14, and S15 Silvia, 180SX, 200SX, and Pulsar GTI-R are the primary targets for an SR20 stroker build. A 91mm stroker SR20DET with appropriate connecting rods, pistons, turbocharger, and supporting modifications is capable of 500–700+ hp in a lightweight, balanced S-chassis platform.

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: BC5209
• Type: 4340 billet crankshaft (standard, non-LightWeight)
• Application: Nissan SR20DE / SR20DET
• Stroke: 91mm (stock: 86.4mm)
• Rod Journal Diameter: 45mm (standard SR20)
• Material: 4340 chromoly steel billet