The World Gasoline Engine is a family of straight-4 piston engines, based on the Global Engine Alliance design. Three engines have been produced: a 1.8 L, a 2.0 L, and a 2.4 L. The initial design of the engine block and cylinder head was handled by Hyundai as part of the Global Engine Alliance. The engines feature an aluminum engine block with siamesed cast iron cylinder liners (which do not allow coolant to flow between adjacent liners). By using cylinder liners, the engine's bore can be altered, therefore the displacement as well, just by adding a different set of cylinder liners. The engine also features an aluminum cylinder head with double overhead camshafts and variable valve timing.