MerCruiser 350 Magnum Alpha Sterndrive Marine Engine Package
Description
Need high-displacement V8 sterndrive acceleration thrust? Select the MerCruiser 350 Magnum Alpha Marine Engine to power performance sportboats and deep-V cruisers. Displacing 5.7 liters across eight 90-degree cylinders, this small-block V8 produces 300 brake horsepower at 5000 RPM. Multi-port fuel injection burns 21.0 gallons per hour at full continuous rating during high-speed open-water runs.
Cast iron alloy construction gives the engine block and cylinder heads outstanding structural stamina under heavy acceleration loads. The cast iron wet exhaust manifolds feature ceramic internal coatings to resist salt corrosion. Package dry weight with Alpha sterndrive scales at 952 lbs. Sump volume holds 5.0 quarts, accepting standard 3/8-inch marine fuel line fittings.
Key Features of MerCruiser 350 Magnum
Boat enthusiasts buy MerCruiser 350 Magnum inboard engine units to upgrade tired carbureted sterndrives with modern fuel-injected V8 muscle. The Alpha One drive pairs with broad V8 torque to provide blistering hole-shot acceleration for wakeboarding and offshore cruising.
- Multi-port electronic fuel injection optimizes air-fuel ratios to maximize horsepower and eliminate vapor lock
- Alpha One gearcases feature hydrodynamic torpedo profiles to maximize vessel top speed on plane
- Roller camshaft valvetrains minimize internal friction to improve engine efficiency across high RPM ranges
- MerCruiser 350 Magnum engine control modules broadcast diagnostic fault codes to scan tools
- Engine Guardian monitors oil pressure and coolant temperature to prevent catastrophic mechanical failure
- Power steering pump packages eliminate helm wheel torque during high-speed cornering maneuvers
- Sacrificial zinc and aluminum anodes protect the outdrive housing against aggressive saltwater corrosion
- Serpentine belt drive systems maintain constant alternator and water pump tension without slippage
Combustion Behavior Thermal Limits
Multi-port fuel injectors supply gasoline at 43 PSI to generate 360 lb-ft of torque at 3800 RPM. Thermostats regulate raw water cooling loops between 160°F and 175°F. Thermal energy exits through the water-jacketed exhaust manifolds and propeller hub discharge. The platform holds a continuous brake specific fuel consumption of 285 g/kWh under cruise power settings.
Transom Alignment Stringer Clearance
The inner transom plate bolts straight to standard Mercury cutouts meeting ABYC P-1 standards. Adjustable isolators secure the front engine block across 22.5-inch stringer beds. Clearances demand a minimum 2.5-inch air gap beneath the stamped steel oil pan for proper bilge air circulation.
Shift Dynamics Boundary Conditions
Fly-by-wire or mechanical shift links actuate the Alpha shift interrupt switch to provide seamless dog-clutch gear disengagement. Raw water strainers demand visual inspection prior to each departure. This high-performance gasoline engine is not engineered for slow commercial pushboats, dry stack exhausts, or continuous running past 5000 RPM.
- Check sterndrive gear lubricant monitor bottles each shift
- Drain water accumulation from fuel filters every 50 hours
- Install fresh engine oil and spin-on filters every 100 operating hours
Factory Warranty Delivery Manifest
Recreational customers receive a 1-Year limited factory warranty on engine and drive components. The heavy wooden crate holds the dressed V8 engine, Alpha One sterndrive unit, transom plate assembly, trim pump, steering ram, and factory service documentation.
MerCruiser 350 Magnum Alpha Specs
| Manufacturer / Brand | Mercury Marine (MerCruiser) |
| Model Designation | 350 MAG Alpha Package |
| Engine Type | 4-Stroke Small Block Inboard/Sterndrive Gasoline Engine |
| Cylinder Configuration | 90° V8 |
| Total Displacement | 5.7 Liters (350 cu in) |
| Bore x Stroke | 101.6 x 88.4 mm (4.00 x 3.48 in) |
| Aspiration & Charge Air | Naturally Aspirated with Tuned Marine Intake Manifold |
| Cooling System Architecture | Thermostatically Controlled Raw Seawater Open Cooling (Closed Cooling Optional) |
| Continuous Power Rating (P1) | 240 BHP (177 kW) @ 4,400 RPM |
| Maximum / Intermittent Power (P3/P4) | 300 BHP (224 kW) @ 5,000 RPM |
| Fuel Injection Platform | Multi-Port Electronic Fuel Injection (MPI) with ECM 555 / SmartCraft Control |
| Cylinder Head Metallurgy | Cast Iron Cylinder Block and Vortec Cast Iron Cylinder Heads (OHV 2-Valves Per Cylinder) |
| Cylinder Liners | Cast Iron Engine Block with Integrated Parent Bores |
| Flywheel Housing & Flywheel | GM Small Block V8 Bellhousing with Heavy-Duty Marine Coupler and 14-Inch Flywheel |
| Electrical System & Ground | 12V Negative Ground Marine Electrical System |
| Starter & Alternator Output | 12V High-Torque Marine Electric Starter / 12V 65A Marine Alternator |
| Lube Oil Sump Capacity | 4.7 Liters (1.24 US gal) |
| Engine Coolant Capacity | 15.0 Liters (3.96 US gal) |
| Dry Weight (excl. gearbox) | 424 kg (935 lbs) |
| Overall Dimensions (L x W x H) | 814 x 740 x 559 mm (32.0 x 29.1 x 22.0 in) |
| Emissions Certification | EPA Marine Tier 3 SI / CARB 4-Star Super Ultra Low Emission |
| Fuel Compatibility | Unleaded Gasoline (87 AKI / 90 RON Minimum, up to 10% Ethanol E10) |
| Transmission / Outdrive Compatibility | Packaged with MerCruiser Alpha One Gen II Sterndrive Leg, Transom Assembly, and Hydraulic Power Trim Kit |
| Factory Warranty Period | Mercury Marine 1-Year Commercial / 3-Year Limited Recreational Warranty |
| Application Research | High-speed sport runabouts, commercial water-ski towboats, coastal harbor security craft, fast pilot dispatch boats, and express daycruisers (20-26 ft). |
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