The Lycoming IO-540 is a six-cylinder, air-cooled, horizontally opposed engine commonly used in general aviation aircraft. It has a displacement of 540 cubic inches and is known for its reliability and performance. The engine typically produces between 250 to 300 horsepower, making it suitable for a variety of aircraft, including small planes and some larger models. This engine features a fuel injection system, which enhances fuel efficiency and power output. The IO-540 is popular among pilots and aircraft manufacturers due to its robust design and ease of maintenance, contributing to its long-standing presence in the aviation industry.