The engineers at Powertrain are also experimenting with a supercharged version of the 6L engine. At this point, the engine is still being tested and evaluated, so no horsepower numbers have been released. However, considering that the naturally aspirated version of the engine is rated at 350 hp, the supercharged edition should hit the charts at well over 400.One of the most compelling aspects of the Vortec marine engines is their durability. Before an engine is released for production, the combination must pass a 300-hour, wide-open-throttle durability test. Since all the major components are retained when a marine engine is packaged for sale through GM Performance Parts, "crate engines" offer this same level of durability. And that's just what every Corvette owner needs.