LO 9-2 Describe the functions, construction, composition, types, and applications of diesel engine cylinder head assemblies

LO 9-02: Describe the functions, construction, composition, types, and applications of diesel engine cylinder head assemblies.

Compacted Graphite Iron

A material from which many new diesel cylinder blocks and heads are constructed is compacted graphite iron (CGI). CGI, also called sintered graphite , is a material produced from powdered iron alloys squeezed into molds at high pressures and then heated to bond the metal particles together. When made from CGI, diesel cylinder heads have approximately the same weight as aluminum but also possess higher strength and rigidity than steel and have sound-damping characteristics. Paccar’s MX-13 diesel engine is an example of an HD diesel using a CGI cylinder block and cylinder head. Paccar reports an increase of 75% in both strength and rigidity, a 200% increase in thermal fatigue resistance, and 150 lb (68 kg) of weight reduction compared to conventional cast iron Figure 7. This means when an engine overheats due to a loss of coolant, cast iron cylinder heads that would normally crack are not as likely to if the head is constructed from CGI material. Ford and first-generation Dodge Ram 3.0 L diesels also use CGI materials in diesel engine blocks and cylinder heads.

FIGURE 09-7: Paccar’s MX-13 diesel engine uses a CGI cylinder block and cylinder head.

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