1955 was without any doubt the blackest year in Heini Walter's career. Walter bought the Merkel-Porsche in good faith and took part in the 1100-cc-sports-car-class, in which he won all races. The engine was inspected by the race direction at the Kandersteg hill climb shortly befor his first Swiss Champion title, and a cubic capacity of 1300 cc was measured, although the capacity of "1100 cc" had been fixed in a contract at the time the car was purchased. Walter was disqualified. He also had to return all trophies he had won during that year and lost his excellent prospects of winning the Swiss Sports Car Championship.

Despite the big disappointment about the lost Swiss Champion title, Walter decided to continue in 1956. The well-known and talented race driver and designer Kurt Sauter from Gempen (BL) made him a chassis with body in which last year's Porsche engine (meanwhile rebored to 1500 cc) was built in. Despite some good results, the project was not a big success and ended with Walter's first serious accident at the St. Ursanne - Les Rangiers hill climb.

The past years were marked by several setbacks. Now, Heini Walter finally also wanted to be a contestant for overall victories. This was only possible with a competitive and reliable car. Therefore Walter bought his first pure Porsche racing car, a Spyder 550. With this car, hes was Swiss Sports Car Champion for the first time and also took part in some races for the first European Hill Climb Championship. At the Swiss Hill Climb Grand Prix from Tiefenkastel to Lenzerheide, Walter was for the first time supplied with a works Porsche.

Driven by the first Swiss Championship title and good results in the European Hill Climb Championship, Heini Walter again changed his car. In this year, Heini Walter bought the Porsche 550 RS from Carel Godin de Beaufort. With it he again won the Swiss Championship title in the sports car category. He was classified 8th in the overall ranking of the European Hill Climb Championship. For the first time he participated in the then very popular airfield races in Austria, in which many top drivers took part.

Although active as a purely private driver, Walter reinforced his efforts to make progress. This contributed to the fact that in 1959, after buying a Porsche RSK from the works in Stuttgart, he won the title of the International German Racesport Champion - and ranking higher than such well-known drivers as Joakim Bonnier and Wolfgang Count Berghe von Trips. He came second in the European Hill Climb Championship, ranking behind Edgar Barth. At the same time, Walter was Swiss Sports Car Champion for the third time in a row.