Engine balance refers to how the inertial forces produced by moving parts in an internal combustion engine or steam engine are neutralised with counterweights and balance shafts, to prevent unpleasant and potentially damaging vibration. The strongest inertial forces occur at crankshaft speed and balance is mandatory, while forces at twice crankshaft speed can become significant in some cases.
Harmonic damper for a 1937 Pontiac engine
Balance shaft system: 1922 design by the Lanchester Motor Company
Fork-and-blade connecting rods
BMW R50/2 flat-twin engine viewed from above, showing the offset between the left & right cylinders
A V8 engine is an eight-cylinder piston engine in which two banks of four cylinders share a common crankshaft and are arranged in a V configuration.
Chevrolet small-block engine, manufactured 1954–2003
Installed AMC V8 engine, manufactured 1956–1991
1909 Antoinette VII aircraft
Vulcan automobile engine (c. 1919)