The Liberty L-4 is a six-cylinder, air-cooled aircraft engine developed in the early 1940s. It was part of the larger Liberty engine family, which was designed to power military aircraft during World War I and II. The L-4 variant was known for its reliability and performance, making it suitable for various applications in aviation. This engine produced around 150 horsepower and was used in several light aircraft and military trainers. Its design emphasized simplicity and ease of maintenance, which contributed to its popularity among pilots and mechanics alike. The Liberty L-4 played a significant role in supporting aviation efforts during its operational period.