L5P. The L5P Duramax is the latest version of the Duramax V8 diesel engine. (engine code Y) Introduced in the 2017 model year it is the most powerful diesel engine GM has produced with 445 hp (332 kW) at 2,800 rpm and 910 lb⋅ft (1,234 N⋅m) at 1,600 rpm.