BMW B58TU Reference Manual page 10

B58TU￿Engine
2.￿Engine￿Mechanical
2.1.￿Engine￿housing
2.1.1.￿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
Index
A
B
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:
Explanation
Cylinder￿head￿with￿integrated￿exhaust￿manifold￿ZIAK¹
Cylinder￿head￿without￿integrated￿exhaust￿manifold￿nZIAK²
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