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