The Toyota UR engine family is a 32-valve dual overhead camshaft V8 piston engine series which was first introduced in 2006, as the UZ series it replaced began phasing out. Production started with the 1UR-FSE engine with D-4S direct injection for the 2007 Lexus LS. The series launched with a die-cast aluminum engine block, aluminum cylinder heads and magnesium cylinder head covers. All UR engines feature variable valve timing for both intake and exhaust cams or Dual VVT-i. Timing chains are used to drive the camshafts. The UR engine has been produced in 4.6, 5.0, and 5.7-liter displacement versions.