Prechamber Mod "Flame" Front

OM616

10mm MW

572

01-25-2011, 03:40 PM #36

(01-25-2011, 02:51 PM)jeemu Yes there is 8 on the side and one on the top or tip of chamber.
Dont remember original diameters of those holes. I do have one set of originals if measure needed.
This is need to done when go over 100hp/cyl
Faster injection is better as you all know.

Thanks Jeemu,

Please forgive me, I am riding in a car, using a friends lap top, while carrying on a conversation, so if I have gone astray please feel free to correct me.

I an doing some quick number crunching and have some data that needs to be commented on by the gallery.

The stock 61X prechamber that I have in my hand has Three 3mm holes, and Two 2.5mm holes, (there is a tiny drain hole in the tip, but I am not counting that in either one), which when added up I get a total of .0480722 sqin of area.

Assuming that Jeemu's prechamber holes were 2.5mm to start with, and there is eight of them, then I get a total area of .060836 sqin.

Now, from the looks of the holes, I am betting that they were drilled to at least 3mm, X eight holes, I get .0876352 sqin.

Now the cylinder displacement of a 60X engine is less than the 61X;

(I am referencing my 603 manual), A 603 has cylinder displacement of 30.314866 cuin, and a 61X has a cylinder displacement of 36.036165 cuin.

If I divide the cylinder displacement of the 61X, 36.036165, by the 61X prechamber hole area, .0480722, I get a 749.62587 to 1 ratio

If I divide the cylinder displacement of the 603, 30.314866 cuin, by the 603 prechamber hole area @ 2.5mm dia holes, .060836, I get 498.30462 to 1

If I divide the cylinder displacement of the 603, 30.314866 cuin, by the 603 prechamber hole area @ 3mm dia holes, .0876352, I get 345.92111 to 1

If I look at these numbers a different way, I see that at 2.5mm, the 60X prechamber has about 26.5% more area than the 61X prechamber, and the 603 cylinder displacement is aprox. 15.7% less than the 61X.

At 3.0mm, the 60X prechamber has about 82.4% more area than the 61X prechamber, and the 603 cylinder displacement is aprox. 15.7% less than the 61X.

Have to stop here. Please comment. Will be back in a bit.

(01-25-2011, 02:59 PM)casioqv This is a very interesting thread to read, but I feel like one practically needs a mechanical engineering PhD to make a useful contribution... so pardon my ignorance posting without one.

I wonder how these engines would run with the entire tip of the prechamber cut off, to essentially make them nearly a direct injection motor. I realize one would probably lose the entire upper rpm range, but would we gain more torque and efficiency like a DI engine?

If the engine were overall more efficient running at lower rpms with more torque, perhaps you could gain back the lost horsepower from the narrower rpm range by simply running more boost and fuel while retaining the efficiency improvement.

//edit: OR would the geometry of an IDI engine with the prechamber opened up make for a very poor running DI engine- having the injector way up inside a tube rather than spraying right into the piston? I suppose there's other differences too- I'm not sure why DI engines always have such low compression ratios compared to IDI ones.

Overall it actually sounds like IDI engines are better for high performance, but DI engines may be better for normal driving where efficiency and torque trump peak horsepower.

Everyone, Please do not be afraid to post your thoughts!!!!!!!!! Regardless of the harshness of a member, every thought on the subject has merit, and sometimes the simplest idea that might seem stupid at the time, can take the discussion in a totally different direction.

Surrounding ones self with people that think just like one, doesn’t promote progression. This is basically brainstorming, there really isn't a wrong answer regardless of what a member says. This is my thread, and I want to hear from everyone!!!!

This post was last modified: 01-25-2011, 04:11 PM by OM616.