Hello,
in gasoline tuning, the exhaust gas temperature (EGT) in the manifold is an important parameter.
The MED9.1 for the 2.0l TFSi calculates the EGT based on hundreds of model data and the current operating condition of the engine (load, lambda...). It also provides EGT values for various points, including in the manifold, before the pre-catalyst, and in the catalyst.
The difference in EGT between the manifold and before the pre-catalyst is typically 140-150K. Unfortunately, the diagnostic scale for manifold temperature ends at 999°C.
A friend wants to "tune" his CDL to "maximum static power" and has installed a sensor at the intake of the downpipe as an EGT control point. Initial tests on the highway with a software for around 330PS showed a maximum of 850°C there. If you add the above 140-150K difference for manifold temperature, you get around 1000°C. However, the EGT in the diagnosis rises so quickly to 999°C that I would expect even more - IF you can trust the diagnostic data of an engine that runs beyond the OEM software limits.
Therefore, I would like to estimate the manifold temperature using a different method, namely the power requirement for the turbocharger.
The compressor power can be calculated based on the LMM value, the intake air density, and the boost pressure. Dividing this by the compressor and turbine efficiency should give you the power requirement, possibly you also need to add something for the friction losses of the bearings.
The exhaust gas mass flow is, in my opinion, roughly "air mass + 8%" (including internal cooling through lambda 0.
. Can you use this to calculate the necessary cooling of the exhaust gas flow, so that the turbine can achieve the pre-calculated power requirement? Then you would only need to add this cooling to the sensor value after the turbine and have a (hopefully) solid value for the manifold temperature...
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