Compared to a standard Duratec 3.5L V-6, the EcoBoost's aluminum block features additional reinforcement ribs to reduce potential flex. The block's open-deck design is a consequence of the die-casting procedure. A die-cast block requires far less finishing machine work, as the contours of the die and block can be made much more precisely, however, unlike sand that can easily be drained from the cavities inside the block after casting, a reusable die must actually be pulled out of the finished block, making it very difficult to cast water jackets inside a closed deck. Since the cylinder sleeves in an open-deck block are only supported at the bottom, deck reinforcements must be wedged between the sleeves and the block to reduce distortion when subjected to high boost. Import racers have been doing this for quite some time.