1950 to 1953. When engines were 1.5 liter supercharged or 4.5 normally aspirated.
Voters:
1954 to 1960. When capacities were cut in half for both engine sizes.
Voters:
1961 to 1965. No supercharged engines. Only 1.3 to 1.5 normally aspirated.
Voters:
1966 to 1985. 1.5 liter turbo or 3.5 normally aspirated.
Voters:
1986 to 1989. The Turbo Era.
Voters:
1990 to 2005. Normally aspirated 3.5 liters.
Voters:
1995 to 2005. Normally aspirated 3.0 liters.
Voters:
2006 on 2.4 litre V8.
Voters: