The Maserati Biturbo high beam headlight uses an H4651 bulb size, while low beam headlights require either H4652 or H4656 bulb sizes. The replacement chart covers vehicle production years from 1983 to 1987 with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Maserati Biturbo uses sealed beam headlight units across all listed model years (1983-1987), meaning the entire lens-and-filament assembly is replaced as one unit rather than swapping an internal bulb.
All three bulb types specified for the Biturbo, the H4651, H4652, and H4656, conform to ANSI standards recognized in the United States and Canada, and all operate on a 12-volt electrical system.
Each of these sealed beam types follows the 4x6-inch rectangular format, a standardized size that was widely adopted in North American automotive lighting regulations.
The Maserati Biturbo high beam headlight position uses the H4651 consistently across the full 1983-1987 model year range.
The low beam headlight position uses the H4652 for model years 1984-1987, while the 1983 model year uses the H4656 instead, making these two years non-interchangeable in the low beam position despite sharing the same physical format.
The H4652 is classified as a variant of the H4651. Although both share the same 4x6-inch rectangular sealed beam construction and voltage rating, they are designated for different beam functions and are not interchangeable between the high and low beam positions.
The H4656, used exclusively in the 1983 low beam position, is a distinct ANSI designation from the H4652 used in later years, and substituting one for the other would not conform to the original specification.