Electrical System; Exhaust System; Exhaust Gas Recirculation System - Detroit Diesel MBE 900 Operator's Manual

ENGINE SYSTEMS

Electrical System

The electrical system consists of
a starting motor, starting switch,
battery-charging alternator, storage
batteries, and the necessary wiring.

Exhaust System

Exhaust gases exit the cylinders
through exhaust ports and the exhaust
manifold. These exhaust gases expand
through the exhaust turbine and drive
the turbocharger compressor impeller.
The gases are then released through the
exhaust pipes and the aftertreatment
device to the atmosphere.
Exhaust Gas Recirculation
System
The purpose of the Exhaust Gas
Recirculation System (EGR) is to
reduce engine exhaust gas emissions
in accordance with EPA regulations.
The EGR system has been optimized
to dramatically cut NOx formation
by routing a measured amount of
exhaust flow to the cylinders to lower
combustion temperatures. Lower
temperatures result in lower NOx
levels without the negative effects of
retarding engine timing. The EGR
valve has been moved to the top of the
engine for improved serviceability.
The EGR system consists of an EGR
cooler, EGR valve, and an EGR mixer.
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DDC-SVC-MAN-0040 0704 Copyright © 2008 DETROIT DIESEL CORPORATION
The MBE 900 engines for on-highway
EPA 2007 regulation applications use
a cooled EGR system along with an
Aftertreatment System to meet the
emission standards.
On the 260 – 350 horsepower engines,
the EGR is fed by all six cylinders.
The low horsepower engines use an
asymmetric turbocharger with two
entries, and the EGR is fed from the
first three cylinders, taken from a small
entry. The exhaust with a maximum
exhaust gas temperature of 730°C
(1346°F) is cooled to a maximum of
150°C (302°F) in the EGR cooler.
The cooled exhaust gases then pass
through the EGR valve and added to
the mixer housing. The addition of
cooled exhaust gases back into the
combustion airflow reduces the peak
cylinder combustion temperature.
Less oxides of nitrogen (NOx)
are produced at lower combustion
temperatures.
All information subject to change without notice. (Rev. 04/08)