Ignition Pressure: Optimize Engine Performance

Hello,
Does anyone know what the ignition pressure is for our TDI engines?
I own an ASZ engine with 96 kW.
What is the increase in ignition pressure for tuned vehicles?
The force acting on the piston, for example, with an ignition pressure of 150 bar, would be approximately 74 kN, which is about 7.4 tons!!
That's quite a lot, especially considering that the crankshaft bearings are only 54mm in diameter, and the connecting rod bearings are 50.9mm. I'm afraid I don't know about "briete."

Best regards, Jürgen.

Hello, if you're referring to 'Zünddruck' as the maximum combustion pressure, it's typically between 60 and 90 bar (approximately 80 bar) in diesel engines. This applies regardless of whether it's a pre-chamber injection system, a direct injection system, or whether the engine is tuned or not.
This is because the diesel fuel burns evenly at approximately 2000 degrees Celsius and the specified pressure, until, in extreme cases, the piston reaches the top dead center (TDC) or the exhaust valve opens.

The peak combustion pressure in Rudolf's engine was likely between 60 and 90 bar.
Currently, the pressure is typically between 150 and 180 bar.

One cannot really speak of an ignition in this context. The combustion likely occurs due to the compression pressure, probably around 60-70 bar.

There was probably a misunderstanding on your end...

Hi!

Here is a script from a thermodynamics lecture; if you are interested, use the link and go to the table of contents, then click on "Diesel Process." There, you will see the isobaric process in a diagram and perhaps get a better understanding of it. And, if you feel like it, all the equations for the exact calculation are also available!

Oops, the link seems to have disappeared. Here it is again.
http://www.peter-junglas.de/fh/vorlesungen/skripte/thermodynamik2.pdf

In TDI engines, the peak (combustion) pressures range from 140 to 170 bar.

To calculate the torque, you need to use the effective mean pressure, because the peak pressure doesn't remain constant.

CU Gremlin.

That's quite a lot, especially considering that the crankshaft bearings are only 54mm in diameter, and the connecting rod bearings are 50.9mm. I'm afraid I don't know about 'briete.'


Therefore, the oil is also the component in the engine that is subjected to the highest stress .

Cu Gremlin.

Yes, of course, to calculate the torque, you need the mean pressure, and I know that.
But my concern was about the stress on the crankshaft and its bearings.


The oil is certainly under a lot of stress, that's undeniable, but the load is still absorbed by the bearings, and the oil creates a metallic separation between the sliding surfaces.
I heard from a workshop foreman (who works at Mercedes) that the maximum ignition pressure is...
It increases to 145 bar under full load.
The temporarily permissible value is even 220 bar.
That would be 13.3 tons in the extreme case for the 220CDI!

Maybe you'll be interested.

Best regards, Jürgen.

Certainly, the oil is under very high stress, no question about that, but the load is still absorbed by the bearings, and the oil creates a metallic separation between the sliding surfaces.


Okay. And that's why the oil transmits the force from the connecting rod to the crankshaft, and is therefore the most heavily stressed component of the engine .

CU Gremlin.

Hi,
Modern common-rail diesel engines operate with a maximum peak pressure of 180 bar. A pressure of 200 bar is planned, but it is not yet available. This is also not the case with Mercedes.