The new 1971 version of the sports prototype came with a flat-12 engine, often referred to as a boxer engine. Many publications added the letter B after the P of its name to indicate its engine type, but this variation was never officially sanctioned by Ferrari which simply called it the 1971 312 P. In addition to a new engine, the chassis also differed in certain respects as aluminium panels were riveted to the small-diameter tubular spaceframe a further step towards the monocoque.