Here's why:
* Larger Diameter Harmonic Damper: Big block crankshafts often have a larger diameter snout to accommodate a larger harmonic damper. A larger damper is beneficial at higher RPMs and with higher horsepower outputs, helping to reduce crankshaft vibrations and improve reliability under the increased stress of forced induction. A supercharger significantly increases the stress on the engine.
* Accessory Drive Compatibility: The snout's design also affects the accessory drive. Some supercharger kits might be designed to work more easily with a big block snout due to pulley spacing and alignment. Using the wrong snout can create clearance issues.
* Small Block Snout Limitations: Small block crankshafts might not be able to handle the increased torsional forces of a supercharger, even if a smaller diameter damper is used. This increases the risk of crankshaft failure.
In short: While not strictly mandatory, a big block snout offers advantages in terms of reliability and compatibility with some supercharger systems, especially at higher power levels. Using a small block snout *could* work, but might necessitate compromises in terms of damper size or accessory drive setup, potentially affecting reliability and performance. Consult with your engine builder or the supercharger kit manufacturer to determine the best snout size for your specific application.
