Sonny Leonard Cause of Death: The Legacy of a Legendary Engine Builder

Sonny Leonard, the founder and president of Sonny’s Racing Engines, passed away on Sunday, January 10, 2024, at the age of 77.Leonard was widely regarded as one of the most innovative and successful engine builders in the history of drag racing and truck pulling. He was known for his expertise in developing big-cubic-inch engines that set records and won championships in various categories.

From Hobby to Business

Leonard started his career as a mechanic at a Chevrolet dealership, where he worked on nights and weekends to earn extra money for his drag racing hobby. He worked on anything that had wheels, from fleet trucks to farm equipment to racers’ cars.

Leonard soon gained a reputation for his skill and knowledge in building high-performance street and strip engines. He moved his business to larger locations to accommodate his growing customer base and equipment. He specialized in big-block engines that could produce more power and torque than the competition.

Breaking Barriers and Records

Leonard’s breakthrough came in 1987, when he sold a 615-cubic-inch engine kit to Bill Kuhlmann, a Top Sportsman racer from Missouri. This feat put Leonard on the map as the pioneer of big-inch mountain motors, which are engines that exceed 500 cubic inches in displacement.

Leonard continued to push the boundaries of engine technology, building engines that ranged from 400 to 1,000 cubic inches. His engines dominated the fields of mountain motor Pro Stock, Pro Nitrous, Pro Modified, and tractor pulling. His engines were also used by some of the most famous names in drag racing, such as Warren Johnson, Rickie Smith, Pat Musi, and Lizzy Musi.

Giving Back to the Community

Leonard was not only a successful businessman and engine builder, but also a generous and charitable person.

Leonard was survived by his wife of 52 years, Frances, his son Larry, his daughter Kelly, and his three grandchildren. He was remembered by his family, friends, customers, and fans as a humble, kind, and passionate man who loved what he did and did it well.


Sonny Leonard cause of death was a sad loss for the racing and engine-building community. He was a legend who left behind a legacy of innovation, excellence, and generosity. He will be deeply missed and never forgotten.