Detroit Diesel MBE 900 Technician Manual page 20

COMPONENTS
The addition of cooled exhaust gas back into the combustion airflow reduces the peak in
cylinder combustion temperature. The formation of Oxides of Nitrogen (NOx) is less at lower
combustion temperatures.
Reed valves are employed on all MBE engines except for model 906. In order to drive exhaust
gas into the charge air, the pressure in the exhaust manifold must be higher than the pressure in
the intake manifold. The pressure in the exhaust manifold changes over time, peaking when
exhaust valves open. Exhaust passes through the reed valves during these pressure peaks. The
reed valves permit transport of exhaust only during the time when the exhaust pressure is greater
than the charge air pressure.
The EGR systems for the MBE 900 and MBE 4000 engines are similar but differ in their specific
components. The EGR components are listed in Table 2-1.
Component MBE 904/924
Asymmetrical
Turbocharger
EGR Valve
Shutoff Valve
Temperature Sensor
Reed Valves
EGR Mixer
* Single-Flute Turbine Housing
Table 2-1 EGR Components Featured on the MBE Engines
2-4
MBE 906
* Yes
Yes Yes
— —
Yes Yes
—
Yes
Yes Yes
7SE940 0505 Copyright © 2005 DETROIT DIESEL CORPORATION
PRELIMINARY
MBE 926 MBE 4000
Yes Yes
Yes Yes
—
Yes
Yes Yes
Yes Yes
Yes Yes
All information subject to change without notice. (Rev. 5/05)