EFU71V-UD Callies Ultra Dirt Crankshaft SB Ford 4.125

Callies has once again established a new standard for lightweight crankshafts. Magnum XL lightening profiles result in crankshafts having extremely high strength to weight ratios. Material is carefully removed from non-stressed areas of each shaft to eliminate parasitic weight. The Callies Magnum XL profile is effective at minimizing windage within the crankcase atmosphere. Oil control is improved by not relying on counterweight undercutting to eliminate weight. All Magnum XL crankshafts feature the Callies Ultra-Case nitride treatment. This heat treatment method produces a deep case that enhances strength while creating an extremely hard load bearing wear surface. The Ultra-Case process generates a layer of hardened steel deep enough to maintain its integrity even after a -.010 regrind. Each main and rod journal is drilled for weight reduction and throttle response improvement. Magnum XL Lightening Profiles Callies unique Magnum XL lightening profiles were developed to optimize material distribution for enhanced strength, superior bearing load reduction, and consistent balance.