Welti trained in business management before buying a dancing school in Zurich, Switzerland. He dabbled with choreography but his great passion was motor racing and he spent four years competing in the local sports-prototype championship, which he won in 1980. It was inevitable that he would meet Peter Sauber, a racer-turned-constructor who also lived in Zurich. When Welti decided to retire from driving, Sauber offered him a job and he became the Sauber team's first motor sports manager. He played an important role in convincing Mercedes to supply Sauber with engines in 1984 and helped to guide the team as it grew to become one of the most important in sportscar racing.In 1986 Mike Thackwell and Henri Pescarolo gave the Sauber-Mercedes team its first win at the Nurburgring 1000kms and, two years later, with backing from the German electrical giant AEG, Sauber battled Jaguar for the World Sportscar title.Mercedes-Benz was convinced to return to racing officially and in 1989 the Saubers were painted Mercedes silver. Jean-Louis Schlesser won the Drivers' World title and the team dominated the Constructors' title, winning seven of the eight races - and scoring a 1-2 victory in the Le Mans 24 Hours with the Jochen Mass/Manuel Reuter/Stanley Dickens Sauber leading home Mauro Baldi/Kenny Acheson/Gianfranco Brancatelli.The following year Schlesser and Baldi shared the Drivers' title while Mass was partnered by the three men from the Mercedes Junior Team who were later to make F1 headlines: Michael Schumacher, Karl Wendlinger and Heinz-Harald Frentzen. The team won the Constructors' title for a second time but did not compete at Le Mans.In 1991 sportscar racing went into decline and Welti was offered the job of being F1 Project Manager for Porsche Motorsport, in a new relationship with the Footwork team. The Porsche V12 engine was, however, a disaster and the company quit F1. Welti stayed on as Competitions Manager, hoping to convince the Porsche management to try F1 again with different engineers. He quit Porsche in 1994 and, after talks with several F1 teams - notably Marlboro McLaren Mercedes - he decided to return to Sauber in May 1995.The victim of political infighting within the team, he was ousted in January 1998. He has since been involved in the running of the V8 Star Championship in Germany.