The Subaru EJ engine is a series of four-cycle automotive engines manufactured by Subaru. They were introduced in 1989, intended to succeed the previous Subaru EA engine. The EJ series is the mainstay of Subaru's engine line, with all engines of this series being 16-valve horizontal flat-fours, with configurations available for single, or double-overhead camshaft arrangements (SOHC or DOHC). Naturally aspirated and turbocharged versions are available, ranging from 96 to 320 horsepower.