6BTA (5.9L) Marine Short Block Diesel Crate Engine Choate Performance

6BTA (5.9L) Marine Short Block Engine

The 6BTA Marine Short Block Engine is engineered for uncompromised reliability in the harshest saltwater environments. Built to serve both heavy-duty commercial fishing vessels and high-performance recreational cruisers, this short block provides a solid, precision-machined foundation for your custom marine build or re-power project.

Key Features

• Vibration Mitigation: A dynamically balanced rotating assembly ensures your vessel runs quiet and smooth, eliminating harmful harmonics that stress your transmission and drive gear.

• Corrosion Resistance: Precision-machined billet freeze plugs are installed to permanently eliminate the "rot-out" common with standard brass or steel expansion plugs in marine applications.

• Blueprinted Precision: Every short block undergoes rigorous CNC machining to correct factory OEM flaws, maximizing oil flow, bearing life, and operational durability under continuous heavy loads.

Machining Process

At Choate Engineering Performance, we don’t just "overhaul" marine engines, we remanufacture them to surpass original factory specifications. Our 6BTA marine engines undergo rigorous CNC blueprinting to correct OEM flaws, ensuring the ultimate reliability required for offshore and coastal applications.

Engine Block Machining

Each of our engine blocks are CNC blueprint machined using state-of-the-art CNC machines. This process ensures perfect dimensions, precise tolerances, and optimal alignment. This starts with decking the surface of the block to achieve the necessary flatness and smoothness (Ra 30 or better) required for flawless sealing with MLS head gaskets. The cylinders are then diamond honed to an extremely tight tolerance to match the piston diameter (within the nearest 0.0001 inch). Following honing, the main bearing bores are line honed to establish a true, straight centerline for the crankshaft. Finally, the cylinder bores are bored to a true 90 degree angle from the crankshaft centerline.

Rotational Assembly Balancing

The balancing of the rotational assembly is crucial for eliminating vibration and maximizing engine longevity. This precision work involves checking and correcting the balance of the crankshaft, connecting rods, and pistons. The crankshaft is thoroughly checked for run-out and inspected for fatigue before being polished and ground to strict concentricity tolerances (0.0005 or less) to ensure the new bearings receive the best possible surface. Rods are inspected and conditioned, and all bearing clearances checked to ensure proper fitment with the new bearings. Each of the pistons, rings, and pin retainers are meticulously weight matched (to a tolerance of 2 grams or less) prior to crank balancing. Then the entire assembly is dynamically balanced on specialized equipment. This ensures that the engine runs smoothly, minimizing stress on the bearings, and extends the overall life of the components.

Components and Parts Included

Engine Core Components

• Cylinder Block

  Crankshaft

  Steel Connecting Rods

  Camshaft

  New Pistons

  New Main Bearings

  New Rod Bearings

  New Cam Bearings

  Main Bolts

  Billet Freeze Plugs

  New Oil Pump

  Upper Oil Pan

  Lower Oil Pan

  Gaskets and Seals

Gaskets and Seals

• Rear Main Seal and Housing

• Front Gear Housing

Marine-Grade Confidence: 2-Year / 2,000-Hour Warranty

When you’re miles offshore, reliability isn’t optional, it’s essential. At Choate Engineering Performance, we stand behind our precision engineering with a comprehensive 2-Year / 2,000-Hour Warranty.

Marine environments subject engines to extreme conditions, from continuous high-idle trolling to sudden wide-open throttle maneuvers. Our warranty is designed to give you complete peace of mind, ensuring your investment is protected against defects in materials and workmanship whether you operate commercially or recreationally.