Yanmar SB8 Marine Diesel Engine

The Yanmar SB8 Marine Diesel Engine is a compact, lightweight, and highly reliable inboard marine diesel engine delivering 8 HP, designed for small boats, sailboats, and auxiliary propulsion needs. As part of Yanmar SB series, the SB8 is known for its simplicity, durability, and fuel efficiency, making it a preferred choice for small vessel owners worldwide.

Engine Design & Construction

The SB8 features a single-cylinder, 4-stroke diesel configuration with direct fuel injection, providing consistent low-end torque and smooth operation. Its robust construction and high-quality components ensure dependable performance even in challenging marine conditions.

Equipped with a freshwater cooling system with heat exchanger, the engine maintains optimal operating temperatures while protecting critical internal components from corrosion caused by saltwater. Its compact and lightweight design allows for easy installation in tight engine compartments, making it ideal for small boats and dinghies.

Performance & Efficiency

Delivering 8 horsepower, the Yanmar SB8 provides smooth and consistent propulsion for docking, maneuvering, and auxiliary sailboat operations. Its mechanical simplicity contributes to low fuel consumption, making it economical for recreational boating and coastal cruising.

Marine Integration

The SB8 is compatible with small marine gearboxes and conventional shaft drive systems, offering flexible installation for a variety of hull types. Its single-cylinder design is balanced to minimize vibration and noise, enhancing onboard comfort for passengers.

Ease of Maintenance & Reliability

The Yanmar SB8 is highly regarded for its simple, service-friendly design. Routine maintenance tasks, such as oil changes, filter replacement, and belt inspection, are straightforward, helping to minimize downtime and service costs. Yanmar extensive global support network ensures ready availability of spare parts, guaranteeing long-term reliability.

Ideal Applications

The Yanmar SB8 Marine Diesel Engine is ideal for:

Small sailboats and auxiliary propulsion systems
Dinghies and small cruising vessels
Coastal and inland waterways
Owners seeking a compact, reliable, and low-maintenance marine diesel engine

Key Advantages

Proven Yanmar marine diesel reliability
Compact and lightweight design
Fuel-efficient single-cylinder direct injection engine
Freshwater cooling with heat exchanger
Smooth operation with low vibration
Easy maintenance with global parts support

Technical Specifications

General

Model: Yanmar SB8
Engine Type: 4-stroke, vertical, water-cooled marine diesel
Fuel System: Direct fuel injection
Aspiration: Naturally aspirated
Number of Cylinders: 1 (single-cylinder)

Displacement & Combustion

Displacement: Approx. 0.316 liters
Bore × Stroke: 70 mm × 72 mm
Combustion Chamber: Direct injection diesel

Performance

Rated Power: 8 HP (6 kW) @ 3,000 RPM
Rated Speed: 3,000 RPM
Maximum Torque: Optimized for low- to mid-range RPM marine operation
Fuel Consumption: Low, dependent on load and propeller match

Cooling & Lubrication

Cooling System: Freshwater cooling with heat exchanger
Lubrication System: Forced lubrication with gear-type oil pump
Engine Oil Capacity: Approx. 2.5 liters
Recommended Oil Type: Marine-grade diesel engine oil

Electrical System

Starting System: Manual or 12 V electric start (depending on variant)
Alternator: Optional 12 V marine alternator for onboard electrical systems

Dimensions & Weight

Overall Dimensions (L × W × H): Approx. 600 × 400 × 500 mm
Dry Weight: Approx. 85–95 kg (engine only, excluding gearbox)

Drive & Installation

Rotation (Crankshaft): Counter-clockwise (viewed from flywheel end)
Drive Type: Inboard shaft drive
Compatible Gearbox: Small marine gearbox for auxiliary propulsion
Mounting: Flexible engine mounts

Service & Adjustment

Valve Clearance (Cold): Intake: 0.15 mm / Exhaust: 0.15 mm
Firing Order: Single cylinder
Maintenance Access: Easy access to filters, belts, and service points

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