Volvo Penta AQ155A: A Reliable Inboard Marine Propulsion Engine The Volvo Penta AQ155A is a classic gasoline-powered inboard marine engine, engineered for dependable boat propulsion in recreational and light commercial applications. Produced from 1969 to 1977, this engine exemplifies Volvo Penta’s commitment to robust marine engineering, delivering consistent power through an integrated shaft and impeller system. Key technical specifications include a crankshaft power output of 160 horsepower (117 kW) from its four-cylinder configuration, likely an inline or V-block layout for optimal balance. With a displacement of approximately 155 cubic inches (2.54 liters), it runs on gasoline fuel, paired with a typical kick-down or single-speed transmission and shiftable gearbox common to era-specific inboard setups. This design ensures seamless integration into vessel hulls, with an alternating firing sequence (1-3-4-2) that minimizes vibrations and enhances overall smoothness. In marine environments, the AQ155A shines with its inboard configuration, providing efficient thrust via direct propeller drive while resisting corrosion and saltwater exposure through Volvo Penta’s durable construction. Its high power-to-weight ratio offers responsive acceleration and maneuverability, ideal for varying sea conditions, and the four-cylinder setup reduces torque oscillations for prolonged component life and operator comfort during extended voyages. Performance-wise, the engine delivers spirited output with quick throttle response, making it suitable for planing hulls that demand immediate power bursts. Though less fuel-efficient than modern diesels, its gasoline fueling supports high-revving operation without the complexity of turbocharging, ensuring reliability in demanding saltwater or freshwater scenarios. Ideal for light to mid-sized vessels up to 25 feet—such as fishing boats, day cruisers, or small tour operators—the AQ155A remains a favored choice for restorations and vintage enthusiasts. It captures the essence of 1970s marine innovation, blending simplicity, power, and Volvo Penta’s legendary serviceability for timeless on-water performance. (Word count: 278)