Prechamber Mod "Flame" Front
Prechamber Mod "Flame" Front
(01-26-2011, 07:33 PM)MTUPower I'll be headed to the yards here in Feb to pull a wagon head for modification. I need more power and less smoke in my wagon, and will be doing quite a bit in search of that goal. A VGT install is high on the list, but every little bit helps. With a spare head I can compare apples to apples with few other variables.
(01-28-2011, 07:59 PM)erling66 I will join in and give my description of the prechamber operation(at full load).Works on stock engines.Mbz did this too millions of diesel stock engines trying to improve performance. Did increase thermal loads on piston,which was of concern. No change in pump timing was ever noted.
The volume of the prechamber is normally 30-40% of the total combustion volume, and during compression, the amount of air in the PC is even less because there is a pressure drop past the orifice. So the theory that most fuel is burnt in the PC is obviously wrong.
The piston compresses the air when it moves to the TDC, then the fuel injection starts and when the pressure(temp) is high enough, the fuel/air mix starts to ignite. That rises the pressure in the PC even more and when this pressure is higher than the pressure in the combustion chamber, the direction of the flow past the orifice is reversed. This happens probably 1-2 degrees before TDC. The small holes in the PC cup makes the burning fuel/air come out as jet steam pointing in every direction. Here(in the combustion chamber) there will be sufficient air to complete the combustion.
The holes in the PC cup are small so that the burning fuel/air will accelerate to a speed sufficient to distribute the mix into all areas of the combustion chamber to make a complete combustion.
I guess that it is only in extreme power increase situations(like Jeemu) where you will notice a power gain by making the holes bigger. In most cases you will only loose momentum of the mix and not be able to to take advantage of all the air in the main combustion chamber.
Forced, something here you don't agree with?
(01-26-2011, 07:33 PM)MTUPower I'll be headed to the yards here in Feb to pull a wagon head for modification. I need more power and less smoke in my wagon, and will be doing quite a bit in search of that goal. A VGT install is high on the list, but every little bit helps. With a spare head I can compare apples to apples with few other variables.
(01-28-2011, 07:59 PM)erling66 I will join in and give my description of the prechamber operation(at full load).Works on stock engines.Mbz did this too millions of diesel stock engines trying to improve performance. Did increase thermal loads on piston,which was of concern. No change in pump timing was ever noted.
The volume of the prechamber is normally 30-40% of the total combustion volume, and during compression, the amount of air in the PC is even less because there is a pressure drop past the orifice. So the theory that most fuel is burnt in the PC is obviously wrong.
The piston compresses the air when it moves to the TDC, then the fuel injection starts and when the pressure(temp) is high enough, the fuel/air mix starts to ignite. That rises the pressure in the PC even more and when this pressure is higher than the pressure in the combustion chamber, the direction of the flow past the orifice is reversed. This happens probably 1-2 degrees before TDC. The small holes in the PC cup makes the burning fuel/air come out as jet steam pointing in every direction. Here(in the combustion chamber) there will be sufficient air to complete the combustion.
The holes in the PC cup are small so that the burning fuel/air will accelerate to a speed sufficient to distribute the mix into all areas of the combustion chamber to make a complete combustion.
I guess that it is only in extreme power increase situations(like Jeemu) where you will notice a power gain by making the holes bigger. In most cases you will only loose momentum of the mix and not be able to to take advantage of all the air in the main combustion chamber.
Forced, something here you don't agree with?