Type 45 (1929-1930) record.

The Type 45 was Bugatti's 16-cylinder (U-16) competition car: two prototypes were built ca. 1929-30, the only 16-cylinder Bugattis ever completed (Bugatti Trust). The 3.8L U-16 used an 84mm stroke. The related Type 47 "Grand Sport" was never built. Sources: bugatti-trust.co.uk/bugatti-type-45-47, en.wikipedia.org/wiki/Bugatti_U-16.