The New Standard for Marine Power: Choate Engineering Marine Division

The New Standard for Marine Power

Choate Engineering Marine Division

At Choate Engineering Performance, we don’t just "overhaul"—we remanufacture marine engines to surpass original factory specifications. Our marine Extended Long Blocks are blueprinted and remanufactured to specifically address catastrophic failure points common in saltwater environments, ensuring offshore peace of mind.

QSB 6.7 Marine Engine
Extended Long Block

Cummins QSB 6.7

Designed for reliability in harsh saltwater environments. Features 24-valve common rail technology for yachts and commercial cruisers.

EXPLORE EXTENDED LONG BLOCK →
6BTA 5.9 Marine Engine
Extended Long Block

Cummins 6BTA (5.9)

The legendary choice for commercial fishing. Refined for absolute mechanical reliability and simple maintenance in open water.

EXPLORE EXTENDED LONG BLOCK →

The Machining Process

Engine Block

Each block is CNC blueprint machined for perfect dimensions. Surfaces are decked to achieve Ra 30 or better. Cylinders are diamond honed to within 0.0001 inch of piston diameter and bored at a true 90 degree angle from the crankshaft centerline. Main bearing bores are line honed to establish a true, straight centerline.

Cylinder Head

Fully machined in-house. Heads are Magnafluxed and pressure tested for cracks or leaks. Valve seats optimized for airflow. Valvetrain geometry is blueprinted to specific tolerances to reduce lifter preload and prolong component life.

Rotational Assembly

Crankshafts are inspected for fatigue and polished to 0.0005 concentricity or less. Rods are conditioned, and all pistons/rings/pins are meticulously weight matched to 2 grams or less before the entire assembly is dynamically balanced on specialized equipment.

Key Marine Features & Fixes

Vibration Mitigation

A fully balanced rotating assembly ensures your vessel runs quiet and smooth, protecting your transmission and running gear from harmonic fatigue.

Enhanced Valve Integrity

Features all-new, upgraded exhaust valves that eliminate high-heat separation, preventing catastrophic engine failure at sea.

Corrosion Resistance

Billet freeze plugs are installed to eliminate the "rot-out" common with standard brass or steel plugs in saltwater environments.

The Extended Long Block Package

Engine Core Components Cylinder Head Components Hardware & Seals
Cylinder Block & Crankshaft Reman Cylinder Head New Head Studs & Gaskets
Steel Connecting Rods New Oversized Valve Seats Billet Freeze Plugs
Marine Pistons New Valve Guides New Oil Pump
Camshaft New Threaded Socket Plugs Turbocharger
New Main Bearings Blueprinted Valvetrain Aftercooler/Intercooler
New Rod & Cam Bearings Magnafluxed & Pressure Tested New Oil Pump
Rockers & Pushrods Precision Decked Surface New Injectors

Built for the Blue

Eliminate the risk of "engine-room anxiety." Choose the Extended Long Block CNC-blueprinted for the open water.

QSB 6.7 Pricing 6BTA 5.9 Pricing