This engine takes the 6.6L Duramax platform into marine service with the marinization and engine management needed for real boat duty. The point is simple: deliver strong diesel horsepower in a lighter V8 package while keeping the fuel-efficiency advantage that pushed many marine customers toward diesel in the first place. With ratings from 350 to 575 horsepower, this setup fits everything from pleasure boats and sport fishers to workboat, commercial, and government service. It has also been used with stern drives, jet drives, and pod drives, so the package is built to work across a wide range of applications.
Gale Banks explained that GM asked him about five years earlier to re-enter the marine market. The engine shown is the result of that effort: a 6.6-liter Duramax-based diesel adapted specifically for marine use. Banks said the marinization work and the engine management are handled by Banks, positioning the package as a purpose-built marine engine rather than simply an automotive diesel moved into a boat application.
The marine Duramax is intended to cover a broad range of applications with output levels from 350 to 575 horsepower. Banks said the rated engine-speed range runs from 3,000 to 3,800 RPM, depending on the version. In addition to those production ratings, he noted that Banks is also developing a "super turbo" version with the Navy that produces close to 800 horsepower, indicating that higher-output variants are already under development.
Banks described the engine as suitable for pleasure boats, workboats, sport-fishing boats, and commercial or military/government service. That range suggests the program is aimed at both recreational and professional marine users who need diesel durability, compact packaging, and substantial power from a relatively light V8 platform.
At its core, the package is a lightweight V8 high-efficiency diesel based on the 6.6-liter Duramax. Banks emphasized the combination of strong horsepower and low weight as a defining characteristic. The engine is intended to give boat builders and operators a diesel option that delivers substantial output without the mass typically associated with larger marine diesels.
The example on display was connected to a stern drive using a Duo Prop arrangement. Banks added that the engine has also been paired with jet drives and pod drives, underscoring its flexibility across different propulsion systems. The point was that the engine is not limited to a single installation style and can be adapted to a variety of hull and drivetrain configurations.
Banks also placed the new diesel in the context of the company's earlier marine work. In the 1970s, 1980s, and early 1990s, Gale Banks marine engines were known for high-performance gasoline packages, including twin-turbo offerings sold around the world. That earlier reputation was built around performance, but market demand shifted over time.
According to Banks, customers increasingly wanted better fuel economy, and in Europe there was especially strong demand for diesel power. That change in buyer priorities helped drive the move from high-performance gasoline marine engines toward a modern diesel platform. The new Duramax-based package is presented as the answer to that shift: a marine engine that combines efficiency with the kind of power output expected from Banks.
The recap of Banks' presentation was straightforward: this is a marine-specific 6.6-liter Duramax program with Banks marinization and controls, available from 350 to 575 horsepower, rated between 3,000 and 3,800 RPM, and adaptable to stern drives, jet drives, and pod drives. With an approximately 800-horsepower Navy development version also in progress, the program appears aimed at users who want high horsepower in a comparatively light diesel package for a wide span of marine applications.