Operational supervision
Exhaust system/supercharging
A3.06.06.00
M20
en / 19.10.93 BA000066 2/3
Ĺ
Assessment of the engine behaviour
The assessment of the thermal behaviour and the engine performance on the M20 engine has been
simplified to a considerable extent by means of a number of new constructional solutions and
higher series precision of the individual components. This also means that tim e-consuming
adjustments and balancing (even when replacing parts) is no longer necessary.
By dynamically controlling the balance of the filling capacity of all the injection pumps among one
another, injection nozzles with flow rates with extremely close tolerances as well as synchroni zed
injection pump drives, a sufficient rate of injection and course of injection (ignition pressure) is
ensured.
For this reason, with the M20, measuring and balancing of ignition pressures between the
individual cylinders is not necessary.
With the range of measuring points at the engine it is possible to assess the the operational
behaviour sufficiently and reliably and a reliable indication if any shortcomings is ensured.
The exhaust gas temperatures after the turbocharger are used for the assessment of the
thermodynamic load condition of the engine. The temperatures after the turbine should not exceed
the full-load figure on the acceptance test records by more than 30 K.
∆t
Exhaust gas temperature after turbine
≤ 30 K
• Compare the exhaust gas temperature after the turbocharger with the acceptance test
records.
If the temperature difference is more than 30 K (∆t > 30 K), the cause of the temperature rise
must be found (different ambient conditions, type of fuel, fouled charger etc.). See also Fault
tracing A3.11.18.nn. Reduce the engine output, if the maximum permissible temperature after
the turbine is exceeded in operation:
Heavy fuel t
Exhaust gas temperature after turbine
max. 400 °C
Diesel oil t
Exhaust gas temperature after turbine
max. 420 °C
• Make another check of the combustion by assessing the exhaust gas opacity.
If combustion is good, the exhaust gas will be invisible or a light grey. For assessment of the
exhaust gas colour see Fault tracing A3.11.18.nn.
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