Which engineer was contracted to design Lamborghini's original V12 engine?

Giotto Bizzarrini was the engineer contracted to design Lamborghini’s original V12 engine.

Ferruccio Lamborghini commissioned Bizzarrini in 1962, before Lamborghini had produced a road car. Bizzarrini’s brief was to create a high-performance 3.5-liter V12, and the resulting engine initially reflected his racing-engine expertise: it used an aluminum construction, four overhead camshafts and a 60-degree cylinder-bank angle.

The prototype was too highly strung for a comfortable grand tourer, so Lamborghini’s own engineers, including Paolo Stanzani and Gian Paolo Dallara, adapted it for production. The road-going version powered the 350 GT, Lamborghini’s first production model, launched in 1964. This is why Dallara and Stanzani sometimes appear in accounts of the engine’s development, but Bizzarrini remains the canonical answer to who designed it.

The basic V12 architecture proved extraordinarily durable. After decades of enlargement and refinement, descendants of Bizzarrini’s design powered Lamborghini models through the Murciélago era, with the original family lasting until 2010.