tl;dr: An interactive, animated deep-dive into how a four-stroke inline-four internal combustion engine works, building up from a simple crank to a full engine with crankshaft, pistons, valves, camshafts, fuel injection, and flywheel. The article explains not just the intake/compression/power/exhaust cycle but also engineering details like hydrodynamic bearing lubrication, piston ring sealing, valve timing offsets, and why a heavy flywheel is needed to smooth out uneven torque delivery.