Exhaust gas turbocharger 4
This chapter is about exploring the installation of turbochargers and the immediate vicinity of one. Because it is no longer the case that such a charger can be found somewhere in the exhaust system. In the interests of the
shortest possible response time, we always find it at the end of the exhaust manifold, where it is the first opportunity to get the total exhaust gas pressure from all cylinders.
In the picture you can see the now classic example with the flange to the manifold at the top right, the turbine housing made of a heavier but more heat-resistant material than that of the compressor. Bottom left the cell for the
wastegate, which is connected to the pressure side behind the compressor. After all, the electrical triggering for the recirculating thrust air valve is at the top left.
Here the turbine has already become part of the exhaust manifold, connected to the compressor, albeit somewhat unusually, by some kind of flange. The V-band flange that is otherwise common here can be found at the
transition from the turbine to the exhaust tract or exhaust gas aftertreatment.
At the top right it's probably the way to the cooling and regulation of recirculated exhaust gases, above the line back to the intake. Also from above the outlet for the compressor, from the left its intake. Below again the pressure
cell for the wastegate. Everything close together and that can even be increased.
It becomes more compact when the turbocharger is more harmoniously integrated into the exhaust tract. The V-band flange again, this time in a very common position, namely between the turbine and the compressor. In
addition, the supply of lubricating oil and probably coolant.
The transition from the wastegate controlled by a pressure cell to that controlled by a stepper motor makes a big difference. It still keeps the greatest possible distance from the heat here, but now with much more precise
adjustment of the boost pressure based on the respective operating status and better monitoring.
A very important step is the integration of the charger with variable turbine geometry in the petrol engine too, which has meanwhile arrived not only at Porsche, but also in the mass production of petrol engines. The picture
also gives a look at the bearing in the middle, its sealing and oil supply.
In terms of boost pressure control, this is a step backwards with the clearly visible wastegate. Not so with the compact design, because the entire exhaust manifold is integrated into the cylinder head, to which the
turbocharger is flanged. It remains unclear whether the additional flushing that this enables brings the engine up to operating temperature faster or cools the exhaust gas better, or both.
We have also forgotten the lambda probe, which has meanwhile moved from its place behind the turbine to the significantly hotter and pressure-technically more problematic one in front of the turbine. It can now withstand it
and thus enables faster feedback, which the engine urgently needs, for example to determine the injection quantity.