Prechamber Mod "Flame" Front

SuperDieselVan

294

01-29-2011, 05:56 AM #98

(01-28-2011, 10:40 PM)OM616 Just to add to the excitement, some more numbers to consider. Not intended to support one idea or another, they are just numbers that might inspire a member to post.

The bore of the 61X (per manual) is 3.58 in diameter, which has an area of 10.065968 sqin.

I have seen some piston to valve clearance measurements in the 2mm range, but for the sake of argument and simplicity lets say at TDC the distance from the head to the piston is .100 inches.

10.065968 X .100 = 1.0065968 cuin at TDC, (probably close with the .100 clearance because of the prechamber tip and prechamber pocket).

The 61X cylinder displacement is 36.036165 cuin

36.036165 divided by 1.0065968 = 35.79999999 to 1 compression ratio

In order to have a 21:1 compression ratio the total combustion area needs to be a little over 1.7 cuin.

40% of 1.7 cuin is .68 cuin

Although I have not cced a 61X prechamber, I would put its volume closer to 1 cuin. I'll try to cc one tomorrow.

I guess your plan is to calculate how much air enters the PC in order to find out how much fuel/air mix is combusted inside the PC.
There are more details you need to take into your calculation.
Remember that the PC is not empty when the compression starts. There will be exhaust that has not escaped and there will be unburnt fuel.
Second, you will have to make calculation at ca20-24 degrees BTDC. The area in the combustion chamber is much larger at that time comparing to TDC. Why? that is probably the time the air flow stops to enter the PC because of the increased pressure caused by the atomized entering fuel.
Maybe it is only 10-15% of the air that is burnt inside the PC

(01-29-2011, 12:54 AM)Hercules 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 thermal load increased because of the increased pressure in the combustion chamber. Not a very desirable situation when you have already increased the pressure by more boost and extra fuel from the larger elements.

(01-29-2011, 02:26 AM)tomnik can we summarise that we want the air flow from compression into the PC with less restriction but reverse we want a "delay" for smooth combustion?
The first step then might be to modify the holes to funnel like from "outside".
Can we learn more when we compare the N/A PC with turbo?
(larger bores, increased inner PC volume).

Tom

Why would we want more air into the PC when we already have the sufficient amount(to perform the PCs task)? To move more of the combustion into the PC will only lead to less efficient engine(energy lost to heat in the PC)
Smooth combustion and better air/fuel mix and a complete combustion is nice to have:o) Mercedes did a pretty good job to create this with their PC

This post was last modified: 01-29-2011, 07:39 AM by erling66.