The rotating assembly is the foundation of any engine build—comprised of the crankshaft, connecting rods, pistons, rings, bearings, and often the harmonic balancer and flexplate/flywheel. Whether you're refreshing a stock bottom end or building a high-output forced-induction engine, the right assembly balances strength, weight, and durability for your power goals.

Our collection includes assemblies in a range of materials (cast iron, forged steel, billet), strokes, bore sizes, and compression ratios to suit daily drivers, weekend racers, and dedicated competition engines. Use the filters to narrow by make, model, and engine family, then review individual product listings for full specifications, included components, and compatibility details.