Chrysler 331ci V8 Marine Engine

The Chrysler 331 Hemi Marine Engine, often referred to by its model designation M-45 or “FirePower” Marine, is the nautical version of the first-generation Hemi. Introduced in the early 1950s, it powered some of the most iconic mahogany speedboats of the era, including those from Chris-Craft and Riva.

In 2026, these engines are highly prized by wooden boat restorers and “traditional” hot rodders who want a vintage Hemi with a unique industrial pedigree.

1. Technical Profile: The “Marine” Hemi

While based on the 331ci automotive block used in the Chrysler Saratoga and New Yorker, the marine version features several heavy-duty upgrades designed for constant high-load operation.

2. 2026 Market Valuation (Estimated USD)

Price depends heavily on whether the engine still has its original marine hardware (manifolds, cooling, transmission).

3. Key Differences: Marine vs. Automotive

If you are planning to “land” a marine 331 for a car, or vice versa, you need to be aware of these 2026 realities:

• The “Water-Jacketed” Manifolds: Marine Hemis use massive, water-cooled exhaust manifolds to prevent engine room fires. These are made of heavy cast iron and are prone to internal “rotting” (rust-through) if used in salt water.

• Rotation: In twin-engine boat setups, one engine usually spins backward (Reverse Rotation). You cannot use a reverse-rotation crankshaft or camshaft in a car without a total teardown.

• The “Short” Water Pump: Some marine versions used a unique, shorter water pump and timing cover to fit in tight engine boxes.

• Gear-Driven Camshafts: Some industrial/marine 331s used gears instead of a timing chain for maximum reliability under load.

4. Critical “2026 Status” Maintenance

• Salt Water Corrosion: If the engine was “raw water cooled” (sucking sea water directly into the block), the internal cooling passages in the block and heads may be paper-thin. In 2026, ultrasonic testing the cylinder walls is mandatory before investing in a rebuild.

• The “Truck” Crankshaft: Marine 331s often feature the high-strength forged steel crankshaft found in Dodge trucks. These are extremely desirable for high-performance builds.

• Modern Fuel: Like all Gen 1 Hemis, the M-45 has soft valve seats. In 2026, it is standard practice to install hardened valve seats to handle modern unleaded fuel without recession.