Schwarczera was born Ernő in the village of Söpte, Vas County. His family moved to Budapest in 1936, where Ernő studied car mechanics. In 1942 the family Hungarianized their name to Söptei. He started wrestling with his younger brother Róbert in the MOM Levente organization, and then he was introduced to canoeing at the Lágymányos water centre. Söptei fought in World War II, where he was taken prisoner by the Soviets. He did not return until 1949. After returning home, he worked as a bus chassis mechanic and then continued canoeing. In 1951 he won the Hungarian championship title with the Budapest Petőfi canoe ten-man team. Alongside his brother, Róbert, he competed in the 1952 Helsinki Olympics, finishing seventh in the C2 10,000 meters. He retired from the sport after the Olympics. In 1956, after the suppression of the revolution, he left Hungary and settled in Canada, where he worked as an advertising agent.