Engine block crankshaft bearings

The present invention relates to bearing supports for a main bearing in an internal combustion engine. An internal combustion engine comprises an aluminum alloy engine block housing pistons in cylinders and having a lower face including an upper semi-circular bearing surface. A lower bearing support has a lower semi-circular bearing surface to complement the upper semi-circular bearing surface in the engine block to define a crankshaft bore to rotatably support an iron alloy crankshaft. The lower bearing support is formed of a single aluminum-silicon alloy having a coefficient of thermal expansion comparable to the iron alloy crankshaft to promote a consistent clearance between the lower bearing support and the crankshaft. Such an aluminum-silicon alloy is comprised of approximately 33-35% by weight silicon and the balance is aluminum.