Description
The Manley Turbo Tuff Series 4340 Billet Crankshaft is engineered for high-horsepower, high-boost Subaru EJ20 applications demanding reliability beyond what OEM or cast cranks can deliver. Fully machined from solid 4340 billet with gun-drilled crank pins, knife-edged counterweights, and optimized oiling passages — this is the foundation for a serious EJ20 build. Special Order — lead times may apply.
Critical Engineering Dimensions
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Part Number: 190040B
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Stroke: 79.00mm (standard EJ20 stroke)
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Material: 4340 Turbo Tuff Billet Steel
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Compatible Engine: Subaru EJ20
Premium Materials & Manufacturing Features
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4340 Billet Construction: Machined from solid billet — not a forging — for maximum material density and dimensional consistency under extreme cylinder pressures.
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Gun-Drilled Crank Pins & Counterweights: Reduces rotating mass without sacrificing structural integrity, improving throttle response and high-RPM stability.
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Knife-Edged Counterweights: Precision-balanced profile minimizes windage and ensures smooth power delivery across the RPM range.
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Multi-Step Heat Treatment & Nitriding: Dramatically increases surface hardness and fatigue life for sustained high-boost operation.
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Shot Peening & Stress Relief: Compressive surface treatment eliminates micro-stress risers that cause premature cracking under cyclic loading.
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100% Magnaflux Inspected: Every crankshaft is crack-tested before shipping — zero tolerance for defects.
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“Direct Shot” Oiling Passages: Optimized oil galleries route lubricant directly from the main gallery to each main bearing journal, protecting bearings under sustained high-load conditions.
