The four-cylinder engine in this Fiat displaces about 28.5 liters, making it among the largest automotive engines ever, and it gives each cylinder around as much capacity as the whole mill in a Chevrolet Camaro Z/28. Once this thing starts firing with no exhaust in place, the look and sound is like a demon at work with a rain of fire and sparks.
This clip is just the trailer for a documentary called the Beast of Turin chronicling the history of this period of racing. The movie also focuses on the rebuild and restoration of the S76 after over 100 years. If the rest of the film lives up to this tease, then it looks like something to watch for.