Jack McInnis: "The alloys and metallurgy used in blocks is a complex subject which has many variables. All of our raw materials come from U.S. suppliers, and the quality of what goes into an alloy dramatically affects strength. Just like in a crankshaft, small amounts of different elements are added to the primary metal to alter its characteristics. Material selection is very important. For example, by adding just 0.02 percent copper to our aluminum alloy blocks, their strength at elevated temperatures is greatly improved. We do not use any remelted scrap in our aluminum because it tends to introduce contaminants. Another drawback of remelted metal is that it tends to have areas which are harder or softer in the finished piece. Variances in the casting process and post-process can also have dramatic effects on strength. Basically, OE blocks use alloys which favor reduced cost while providing adequate strength for their intended purpose, and aftermarket blocks utilize alloys which give elevated performance and strength levels. There are also some aftermarket blocks appearing on the market from offshore sources which are made from alloys based more on OE specs, but are very inconsistent in their strength and hardness properties.
"In our aluminum blocks, we use C355-T6 aluminum over the more common A356-T6, which is the strongest material available for manufacturing blocks and yields a highly consistent casting. A C355-T6 alloy remains very strong until 300 degrees, whereas 356-type alloys begin to lose their strength at 200 degrees. That 100 degree difference is very important in a high-performance engine. Plus, C355-T6 is extremely crack resistant, easy to repair, and has excellent tensile elongation properties."
Jason Neugent: "Brodix offers a block for small-block Chevys with a 4.500-inch bore spacing, and a block for big-blocks with a 5.000-inch bore spacing. This rewrites the book as far as displacement potential. These two blocks include the same design features and strength that Brodix blocks are known for. The difference is that their larger bore spacing allows for bigger bores and greater displacement figures. The 4.500-inch bore space blocks include features such as a 0.391 raised cam, deck heights from 9.000 to 9.625 inches, and lifter bores up to 0.937-inch. This block also includes reinforced lifter valleys, billet main caps with splayed bolt patterns, and sleeves with thick registers. The 4.500-inch bore space block will allow bores up to 4.250 inches, and gives you the potential to build a 500-plus-cubic-inch small-block. Likewise, the 5.000-inch bore space Rat motor block allows bore diameters up to 4.750 inches, which when combined with its taller deck height offers the potential of 800-plus cubic inches. This block features a 1-inch raised cam, billet main caps with a splayed bolt pattern, sleeves with thick registers, and a reinforced lifter valley. Deck heights from 11.200 to 11.625 inches are offered, and lifter bores up to 1.062 inches are available options. The larger bore spacing of these blocks is achieved by spreading out the center mains, so they require a custom crank, heads, and intake manifold. We already have heads for our 5.000-inch bore space blocks, along with adapters that allow running a standard BBC intake. These parts are also under development for a 4.500-inch bore space Mouse motor block."