Mario Illien

Prior to embarking on his motorsport engineering career, Illien trained as a technical draughtsman. He later returned to education to study for a degree in mechanical engineering at Biel University’s School of Engineering. He graduated in 1976 and resumed his engineering career.

Illien took his first motorsport-related job with his idol Bonnier in 1971, assisting with the preparation of an old customer McLaren chassis. When Bonnier was killed in a Lola T280 at Le Mans in 1972, Illien was hired by Fred Stalder to modify a four-cylinder Chrysler-Simca for use in a Le Mans prototype run by Stalder's Racing Organisation Course team. It was later used in Formula 2 in the mid-1970s, but by that time, Illien had left Stalder’s employ and enrolled at Biel.

After his graduation, his career moved away from motorsport and into military engineering. He joined Mowag (now owned by General Dynamics) in Kreuzlingen, designing diesel engines for armoured vehicles.

During his time at Mowag, Illien maintained his interest in motorsport. In 1979, at the age of 30, he gave up his job and moved to the UK to work in the design department of Cosworth Engineering in Northampton. He spent five years at Cosworth, contributing to the design and development of the company's racing engines, including the DFY V8. It was at Cosworth that Illien met Paul Morgan and the next stage of his career began.