FNM 42HPEP-350 MerCruiser Bravo Three Sterndrive Diesel Package

Description

Obtain high-speed tactical propulsion and zero propeller torque walk with the FNM 42HPEP-350 Bravo Three Sterndrive Package, turning 350 BHP at 3,800 RPM from a 4.2L inline-6 block. The counter-rotating Bravo Three XR outdrive provides immediate planing thrust, though operators must enforce 2-micron diesel fuel filtration and maintain sterndrive gear oil inspection routines.

Engine architecture combines an ASTM parent-bore cast iron block with a 24-Valve cast iron monobloc cylinder head and single overhead camshaft. Electrical components operate on a 12V negative ground system powered by a 12V 2.8 kW starter motor and a 12V 120A marine alternator. Dry mass totals 992 lbs across an engine stance measuring 45.3in long by 28.3in wide and 30.9in high. Sump oil volume equals 2.77 US gal.

Key Features of FNM 42HPEP-350

Offshore patrol commanders buy FNM 42HPEP-350 dual-prop packages to equip pursuit craft with unmatched acceleration bite. This complete commercial workboat diesel engine repower system includes a heavy-duty Mercruiser Bravo Three XR counter-rotating outdrive and hydraulic power trim.

• Counter-rotating dual propellers cancel steering torque and provide straight tracking during high-speed tactical maneuvers.
• High-boost variable geometry turbocharger alters exhaust gas flow to produce high low-end boost without turbo lag.
• Mercruiser Bravo Three XR sterndrive package includes heavy-duty gear sets, transom plates, and trim cylinders.
• Common rail direct electronic fuel injection operates at 1,800 bar to eliminate soot on boat hulls.
• Oversized seawater intercooler drops intake manifold temperature to sustain 350 BHP peak output.
• Monobloc 24-Valve cast iron cylinder head handles severe thermal stress during high-speed emergency response runs.
• Heavy-duty 12V 120A alternator provides abundant electrical current for radar displays and tactical communications gear.

Dynamometer Dual Prop Load Test Tolerances

Factory dynamometer testing validates 250 BHP continuous power at 3,200 RPM and 350 BHP intermittent output at 3,800 RPM. Peak shaft torque reaches 495 ft-lbs at 2,400 RPM under maximum turbocharger boost of 2.0 bar. Rail fuel pressure maintains 1,800 bar during sustained wide-open throttle tests. Pre-turbine exhaust gas temperatures peak at 1,180°F under high boost. The closed-circuit heat exchanger holds internal coolant at 185°F. Main journal runout measures 0.0004in TIR, and lube oil gallery pressure settles at 52 PSI across a 25° tilt.

Interceptor Dual Prop Maintenance Guidance

Electronic helm throttle levers operate with 1 lb of smooth control action without mechanical friction. Do not drop this high-boost sprint engine into continuous displacement pushboats, coastal trawlers, or slow freight barges running 24-Hour bollard thrust. The sprint profile is engineered for commercial workboat diesel engine repower installations on fast interceptor craft and security patrol boats.

• Drain engine lube oil and replace spin-on oil filters every 250 operating hours with 15W-40 oil.
• Replace primary 2-micron fuel water separator filter elements every 250 operating hours to preserve injectors.
• Inspect Bravo Three XR gear lubricant and replace sacrificial zinc anodes every 150 operating hours in seawater.

Complete Marine Package Warranty Manifest

FNM CMD backs this complete propulsion package with a 2-Year limited marine manufacturer warranty. The factory shipment includes the 4.2L bobtail engine, Mercruiser Bravo Three XR sterndrive leg, transom assembly, hydraulic trim pump, 12V starter, 12V 120A alternator, digital instrument panel, wiring harness, and official installation manuals.