An assembly includes a cylinder head with an integrated exhaust manifold that has four exhaust flow passages directing cylinder exhaust from inlets arranged to correspond with exhaust from the four cylinders, respectively, and has only three outlets. The assembly includes a twin scroll turbocharger having a housing with a first scroll passage, a second scroll passage, and only three inlets. Two of the exhaust flow passages join in the cylinder head to direct exhaust flow into only one of the inlets of the housing and through the first scroll passage. Exhaust flow through the other two of the exhaust flow passages flows separately into the other two inlets in the housing and joins in the housing to flow through the second scroll passage.