Yanmar 2QM20H Marine Diesel Engine The Yanmar 2QM20H is a robust, inboard diesel engine engineered for reliable propulsion in marine vessels. Manufactured by Yanmar Co., Ltd. of Japan and produced until 1984, this discontinued model exemplifies classic marine engineering with its focus on durability and efficiency for small to medium-sized boats. Key technical specifications underscore its compact yet capable design: a twin-cylinder, in-line configuration with a 4-stroke cycle, delivering 22 horsepower (16 kW) at 2800 RPM per DIN 6270B standards. It features a bore of 90 mm and stroke of 88 mm, contributing to a lightweight build at just 190 kg (418 lbs), ideal for space-constrained installations. Powered by diesel fuel, the engine ensures high thermal efficiency and low emissions through its optimized combustion system, with no specified reduction gear but adaptable for direct inboard mounting. In marine applications, the 2QM20H shines with benefits tailored to harsh saltwater environments. Its inboard placement optimizes hull weight distribution, lowering the center of gravity for enhanced vessel stability during rough seas. The diesel compatibility provides exceptional fuel economy and extended runtime, minimizing refueling demands on long passages, while the robust construction minimizes maintenance needs, aligning with Yanmar’s renowned reliability. Performance characteristics include smooth, vibration-dampened operation from the balanced twin-cylinder setup, balancing power output with engine longevity at peak RPMs. This results in dependable torque delivery for consistent cruising speeds without excessive wear. Ideal for auxiliary propulsion in sailboats, personal watercraft, or compact fishing vessels, the 2QM20H remains a cost-effective choice for boaters seeking proven, low-maintenance performance. Its adherence to international standards ensures seamless integration, making it a timeless option for retrofits or heritage restorations in recreational and light commercial marine use. (Word count: 278)