After updating the Countach with the 5000 generation, Giulio Alfieri intervened on the engine. Having rejected the idea of adopting the turbo, the increase in power was obtained with new four-valve cylinder heads. The displacement increased slightly (5167cc) and the power reached 455 horsepower, about 80 more than the 5000S. The LP5000 Quattrovalvole remained in production from 1985 to 1988, ie the day after the sale of the brand to the Chrysler group.