Thanks David. That little engine won multiple World Championships across multiple series.
https://en.wikipedia.org/wiki/Fiat_Twin_Cam_engine
Motorsport
The Fiat Twin Cam engine has been widely used in motorsport and has been the most successful engine in the history of the World Rally Championship. The World Rally Championship for Manufacturers has been won by Fiat and Lancia, using engines based on the Lampredi Twin Cam engine, for a total of 10 years.
The four valve version made its first appearance in the Group 4 competition version of the Fiat 124 Spider Abarth, where it had 1.8 litres. Group 4 regulations at that time allowed the use of a cylinder head of a "free" design. This engine still used a three-piece cylinder head design with an included valve angle of 46 degrees.
In later years motorsport regulations were changed so that the use of four valve heads was only possible when the homologated cars had four valve heads. Therefore, the homologation series of the Fiat 131 Rally Abarth came with a two-litre version of the four valve engine.
These engines were later used in the mid-engined Lancia 037, where they were supercharged and eventually enlarged to 2.1 litres.
In addition to the titles in the World Rally Championship, the Fiat Twin Cam equipped the Lancia Beta Montecarlo turbo, that won the World Sportscar Championship for two consecutive seasons in 1980-1981.
Constructor
Car used in World Championship
Seasons
Manufacturers' titles
Fiat
Fiat 124 Abarth
1970–1975
—
Lancia
Lancia Beta coupe
1974–1975
—
Fiat
Fiat 131 Abarth
1976–1982
3 (1977, 1978, 1980)
Lancia
Lancia 037
1982–1986
1 (1983)
Lancia
Lancia Delta HF 4WD and Delta Integrale
1987–1993
6 (1987–1992)