Warum sind PDs obenraus so "lahm"? | Posts 64+

Thomas wrote:

Even with "significantly increased" injection amounts, the turbocharger pressure is still increased, which also has a cooling effect on the exhaust gas temperature. Most turbos fail due to excessively high exhaust gas temperatures or over-revving, which causes the bearings to fail. This often happens in tuned engines.

Hi Thomas,

I want to revisit that topic again.

I now understand that the exhaust gas temperature (EGT) decreases because more air in the cylinder leads to a higher combustion speed.

However, the LLT seems to contradict this (at least initially).
The charging power, and consequently the task of the liquid cooling system (LLK), increases "almost quadratically" with the charging pressure.
For example, in my Polo with a turbocharger pressure of around 1.3 bar, I recorded low-temperature coolant (LLT) temperatures of up to 80°C on the highway (at an outside temperature of around 10°C), while the 66 and 81 kW models with 1 bar of boost, despite having a less powerful LLK (low-temperature coolant system), tend to be closer to 50°C.
And as far as I know, the exhaust gas temperature (EGT) changes almost proportionally to the load limit temperature (LLT).

If one were to command a higher boost pressure (e.g., 1.5 instead of 1.3 bar) in my Polo, which currently has the standard air-to-air intercooler + fog lights located in front of the intake , the intake air temperature would likely exceed 100°C.

Could the higher burning speed "more than compensate" for that?
Because only then could the EGT (Exhaust Gas Temperature) decrease due to increased boost pressure.