Prechamber Mod "Flame" Front

OM616

10mm MW

572

01-24-2011, 01:23 PM #20

(01-24-2011, 09:05 AM)ForcedInduction I don't need to prove anything since Mercedes' team of engineers already did the all work over the last 50 years and were nice enough to publicly document it.

OK, Just to be sure that I understand your technical understanding and position regarding the 617a prechamber; you are telling everyone that your position is based on some one else’s efforts, (in this case MB), and not your personal technical / theoretical knowledge. In other words, you are declaring that your position is based solely on what you read, and that MB perfected them to make the maximum power before they released a single engine.

Nothing wrong with that, it just limits your understanding to the perspective of those whom have published the information that you rely on for all your knowledge. "Trust, but verify", I guess you trust more than verify.

I am trying to find some depth to you, some outside the box understanding of theory, but all we get back are one liners referencing others understanding, (from their Perspective), and work. I and sure we would all be thrilled to read about your theories. I could help you out and try to paste together a paragraph using all your one liners, but there isn't much technically relevant to work with in them.

You have a following of believers, although I see that some have broken from the flock recently. I agine am providing you an opportunity to show an example of depth, of some knowledge of theory that you have obtained yourself, that is, not solely from something you have read. Anything, we don't care at this point.

(01-23-2011, 01:08 PM)OM616 Again, one line referencing of information that some one else did, in this case an ASE study, is not a response with any technical depth.

(01-24-2011, 09:05 AM)ForcedInduction Okay then, lets see your ASE paper.

We are not talking about ASE's technical depth. Lets stay on point here. The previous post offered you the opportunity for you to demon straight your technical depth, and understand of theory, by disseminating the massive amount of information in the ASE report, (which has to be purchased), and translate the portions you think are relevant to this topic, and which are the bases of your position, so that all of us can have a clear understanding of where you are coming from, technically that is.

For an example of such written constructions, go to my thread http://www.peachparts.com/shopforum/show...p?t=232935
Several people have written very good technical agruements based on their understanding, and some of mine are in there as well as it is my thread. Also I thought it would be aproprate to copy and paste a PM that I responed to the other day.

Senders identity is with held to protect the innocent;

“Figured I'd ask via PM so there's no flame war started.

Happen to have any more info on how the torque curve/peak and hp curve/peak are related to the prechamber design? I'm looking through the peachparts thread, some good musings in there, maybe I just haven't hit the real good stuff yet.

Glad to see someone pushing the envelope in new and different ways!

Hope all is well,

XXXXX”

Relevant portions of my response;

Any way, I have measured the pressures in the cylinder and prechamber during compression, (pressure differential), at different piston velocities, and found that above 2000RPM the 616/617a prechamber VE really starts to fall off. Boost increases the cylinder pressure, and in turn helps the prechamber VE, but also creates tremendous pre-injection cylinder pressures and temperatures.

With out increased fuel delivery at the bottom end, the torque will not vary much because the prechambers VE is adequate for the slower piston velocities and expansion volume from the quantity of fuel that is delivered over the length of time, by the stock elements. The benefits of increasing the high speed VE of the prechamber can be seen in the drop in EGTs at high speed operation.

(After reading this again, I thought I would expand on the thought. The prechamber seems to be calibrated around a couple of variables, 1) being piston velocity and max cylinder volume, and 2) the pulse width of the injection, which for the most part sets the rate of expansion by slowly injecting fuel over a long time vrs, the same amount of fuel in ½ the time. With the slower injection, the pressure builds slower and can be bled through smaller holes over a longer period of time, allowing sufficient residual pressure to be sustained in the prechamber after the cylinder pressure has dropped. If larger elements were used, a given amount of fuel would be injected faster and the pressure curve would be steeper, (would riser quicker), there for, higher flowing holes would allow a faster release of the pressure, (more torque). Since the injection was shorter, the length of time the sustained pressure would need to be maintained to support continued combustion would be less. My goal with the 10mm elements is to be able to get the fuel injected and burnt before the cylinder pressure starts dropping, at that point the holes as calibrated orifices are not needed, and I can get as close to a direct injection with an external combustion chamber as I can get.

On the other side, if the boost is increased, the max cylinder volume is increased, which will require higher flowing holes to allow the additional air to make it into the prechamber at high piston velocities. Now one could argue that with out additional fuel, the increased holes would allow the prechamber pressure to drop too soon. Possible, I would point out that there is a higher volume of gasses in the prechamber creating a higher pressure at the start of injection. As long as the pressure stays above that which is needed to promote complete combustion for the length of time that is required to burn the injected fuel, all should be well and balanced)

The governor reduces the fueling at high speeds because the prechambers can't breath that well, and the fuel needs to be reduced to that which can burn in the lower O2 environment. In other words, the holes are sized for an engine operating speed of 55 mph at most, any faster and the increased volume of expansion gasses from the additional fuel needed, to run faster or make more power, simply can't get out of the prechamber before the next compression cycle starts. (At high speeds the prechamber never fully depressurizes and scavenging is reduced resulting in a dirty combustion environment, which generates smoke and high EGTs). (Determined from my pressure differential tests on 616/617a prechambers)”

Now that there are many examples of how to structure a technical response, there really is no excuse why we can not see a multi paragraph counter argument. Apposing thoughts are productive as long as they are well thought out and explained in context with supporting foundation.

(01-24-2011, 12:17 PM)dieselboy They've been modifying precups for years in the idi's.

Did you order the same 10mm elements that Shredator used?

This post was last modified: 01-24-2011, 06:18 PM by OM616.