Patent ID: 8360036

Claim:
A method of improving engine operation, comprising: combusting an air-fuel mixture in each cylinder of an engine, each cylinder including a direct-injector; routing exhaust gases of each cylinder through a single exhaust manifold, the single exhaust manifold integrated into a cylinder head, the single exhaust manifold having an inner pair of exhaust runners and an outer pair of exhaust runners, the inner pair of exhaust runners having a smaller cross-sectional area than the outer pair of exhaust runners, a turbocharger coupled to the single exhaust manifold; deactivating solely one exhaust valve of each cylinder when engine speed is less than a first threshold engine speed while leaving at least one exhaust valve of each cylinder active, the deactivated solely one exhaust valve of each cylinder deactivated for at least two engine cycles; and activating the solely one exhaust valve of each cylinder when engine speed is greater than a second threshold engine speed, the second threshold engine speed greater than the first threshold engine speed.