Porsche engineers wanted a large-displacement engine to power the 928, and prototype units were built with a 5-litre V8 engine rated at nearly . Ferdinand Piëch wanted this car to use a 4.6-litre 90 degree V10 engine with 88 mm bore spacing, a derivative of the Audi 5 cylinder engine, which in turn is based upon the Volkswagen EA827 unit. The Porsche board objected as this move would give rise to a rumour of a new 911 with a front-mounted six cylinder engine, but also it is theorized that the board wanted to maintain some distance from the Volkswagen group.