Dumesny switched to Sprintcars in 1983/84 and had his first major win that season when he won the 1983 Wayne Fisher Memorial at the Parramatta City Raceway in Sydney.
In 1984, Dumesny linked with Melbourne based motor and racing expert John Sidney, driving for Sidney's OTR (Oval Track Racing) and started driving an Australian made OTR Defender Sprintcar with instant success, winning both the Victorian and South Australian championships.
Early in his Sprintcar career, Dumesny also travelled to the United States to race in selected World of Outlaws events as well as the famed Knoxville Nationals.
On 16 May 1992, Dumesny continued to show his versatility when he swapped his Sprintcar for a Speedcar and won the 34th Australian Speedcar Grand Prix held at the famous Sydney Showground Speedway joining such drivers as A. J. Foyt, Steve Kinser, Sleepy Tripp, Garry Rush and George Tatnell as winners of the annual event.
[2] Max Dumesny, his longtime backer John Sidney along with longtime (and current) major sponsor Valvoline (sponsorship secured in 1988) branched out in other forms of motorsport in the early 1990s when Max drove a JSR (John Sidney Racing) prepared Oldsmobile Cutlass in the Australian NASCAR Championship, winning the 1992/93 national championship.
[3] In a 2014 video interview for the Sydney Speedway's YouTube channel, Dumesny confessed that after starting in Formula 500's he thought his career would last "about 5 years" before he got out, got married and had kids who would never know he had raced.