BMW 5 Series: Cylinder head

The following figures show the two cylinder head variants with and without the cylinder head-integrated exhaust manifold.

Cylinder head of B58TU engine

1. Cylinder head with integrated exhaust manifold ZIAK¹
2. Cylinder head without integrated exhaust manifold nZIAK²

ZIAK¹ = cylinder head-integrated exhaust manifold

nZIAK² = non cylinder head-integrated exhaust manifold

With the gravity casting process the aluminum alloy is embedded into a prefabricated mould of steel and sand using gravity. The result is a cylinder head made from aluminum gravity die casting AlSi7MgCu0.5 T5.

The cylinder head of the B58TU engine in the medium power level is a new design. The exhaust manifold was integrated in the housing of the cylinder head. Depending on the engine output, the engine weight, the operating strategy of the engine and the cooling surfaces, the exhaust manifold is integrated in the cylinder head housing and the exhaust turbocharger is interlocked at the cylinder head.

Owing to the higher mechanical and thermal loads, gasoline engines in the upper power levels and higher have a traditional cylinder head without the exhaust manifold integrated in the cylinder head.

The following benefits could be achieved with the integration of the exhaust manifold in the cylinder head housing:

• Benefits in fuel consumption and pollutant emissions due to faster warm-up of the engine.
• Weight reduction with the use of aluminum instead of steel.
• Cost reduction by eliminating the need for a separate exhaust manifold.
• Simple disassembly and installation both of the cylinder head and the exhaust turbocharger.

The following table provides an overview of the engine versions that use a cylinder head with an integrated exhaust manifold:

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