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  #31  
Old 11-16-2008, 02:25 PM
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Quote:
Originally Posted by tomnik View Post
I also started to think about PC modification a while ago.
I got the fab drawings for the 616, rounded end PC, the 617a PC and the 606 (177 HP) PC.

Tom

Where did you find the prints? Any chance you could find it in your hart to make some copies for me. I am trying to find the changes that have been made to PCs to date. Any specks to compare to would be very helpful.

I have not had one in my hand yet or seen if there is any more room in the head PC cavity to increase the PC volume. I would not hesitate to make my own PC taking advantage of the best of all designs.

I would have to see the surface finish you are speaking of. To a point a non smooth surface is utilized to create micro turbulence to keep fuel from condensing on the walls of a port (wall Wetting). But there is a point where the turbulence goes from productive to destructive and inhibiting flow. Helical grooves could be cut into the PC chamber to enhance and quardinate swirl. (if I made my own).


"BUT, I am sure there is potential in the PC although I was told that the C111 had no PC mods. The PC will become a bottleneck >250 HP."

I am going to blaze new trails. So far I have not found anyone that has provided any proof that they have tried to mod any PC, what they did EXACTLY, and what the results were. IMO it is a matter if efficiency. IDI engines on average consume more fuel per HP than DI engines (there are extreme losses, and the point of the PC is to run cleaner [burn more efficiently], this tells me that there is room for improvement, apparently MB thought so too as the 603 engine has smaller cylinders and yet a larger PC volume and different burn holes). IDI engines generally will run higher RsPM than DI engines. I want to get as close to a DI engine while retaining the benefits of the IDI engine. Yes the C111 made good power at the settings they had, but perhaps it would have made more power if they had brought the PCs up to date so to speak. Of the C111 project, I can not intelligently speak as I am not familiar with it.

My thinking is everyone is using higher levels of boost than is necessary to artificially increase the PC VE. I may be setting my self up for a big I TOLD YOU SO ,but that is OK. I have seen lots of threads where people say they want to try something with the PC, then nothing after that, no good or bad. There is one way to find out.
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  #32  
Old 11-18-2008, 04:36 PM
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Quote:
Originally Posted by OM616 View Post
Helical grooves could be cut into the PC chamber to enhance and quardinate swirl.
A helical grove in the prechamber throat will not provide any benefit on an OM616 or OM617 engine. This is because to enhance combustion you must move fresh air through the area where the atomized fuel is. A helical grove would just move the same air around the outside perimeter of the atomized fuel zone.
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  #33  
Old 11-18-2008, 06:41 PM
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Quote:
Originally Posted by ConnClark View Post
A helical grove in the prechamber throat will not provide any benefit on an OM616 or OM617 engine. This is because to enhance combustion you must move fresh air through the area where the atomized fuel is. A helical grove would just move the same air around the outside perimeter of the atomized fuel zone.

Yes you are correct. That is what I am looking for, brain storming online. Please don't be afraid to through in an idea or thought you might have.

I have been reading up on 300+ Hp 603 engines. They all are running at least 30Lbs of boost, one was in the low 40s. They ran very clean which is to say there is more air than fuel. In post #30 Tomnik, says the 603 PC chamber volume and the holes are larger than the 61X PC. That is interesting in that the individual cylinder volume is less in a 603.

I have only seen pictures of the 603 PC installed in heads, and one major difference I see is it has a burn hole in the bottom. That would create a fresh air jet, parallel to the centerline of the PC, as apposed to the 61X PC which only has, what I am guessing, is about 60* burn hole angle to the centerline. The jet ricochets off the wall of the burn tube. This would cause lots of action in the tube but I can't imagine it would be as affective in supplying fresh air the PC it self as a direct shot to the ball.

I was thinking last night about what it would take to build a high pressure flow bench to measure the PC burn hole flow in both directions. The stock 61X and 603 PCs could be tested and compared proportionately to there respective cylinder displacements.
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  #34  
Old 11-26-2008, 12:59 PM
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I was recently reading in a BOSCH diesel injection book about prechamber vs swirl chamber designs. The book quoted a 20% increase in efficiency of a swirl chamber engine vs prechamber do to the increased pumping losses. This is pretty compelling evidence suggesting that those holes could be bored out. Going with larger holes will probably increase noise and worsen cold start ability.
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  #35  
Old 11-28-2008, 07:33 PM
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Whatever you do to the holes at the end of the prechamber tube will have no real effect on the air flow in the prechamber. The way to get effective swirl in the prechamber was patented by Mercedes in about 1985. They did it by modifying the impingement pin/ball by making the bottom of the ball angled. As the air entered the through the flame tube it hots the angled base of the ball. This induces flow perpendicular to the injected fuel and circulates fresh air close to the top of the impingement pin where the fuel is atomized.

They incorporated these changes in the 86 and 87 OM603 prechambers. It would be possible to make new prechamber pins for the OM617 that did the same thing.
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Last edited by ConnClark; 11-28-2008 at 07:40 PM.
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  #36  
Old 11-28-2008, 08:18 PM
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Looks like I need to get a 603 PC to see how to apply the changes to the 61X PC.

Anyone got the part # for the latest 603 PC?
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  #37  
Old 11-29-2008, 03:55 AM
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Quote:
Originally Posted by OM616 View Post
Looks like I need to get a 603 PC to see how to apply the changes to the 61X PC.

Anyone got the part # for the latest 603 PC?
sorry for my late and incomplete answer I promised.

I can't find the 606 PC drawing. I thought I had it but it is not in my PC box.
What I remember is that the inner volume was increased.

Here some part numbers:

engine PC

617 912 (80 hp) 615 010 0152
617 912 (88 hp) 615 010 0152
617 952 617 010 0352

606 962 606 010 0452

The main difference between 61x and 60x is the angled assembling of PC and injector. 60x have the thread for the injector (those with the low positioned thread) directly integrated in the PC, while the 61x use the extra thread ring for fixing the PC in the head and providing the thread for the injector.
Plus the flatted ball is deflecting the incoming air to one side to give an oriented swirl flow, corresponding to the angled injector. Two different systems that could not be mixed (in my opinion).
Further the hole for the GP is on a different position and also the axis of the ball.
The big exception is the intermediate PC design of the MB100 (light truck).
Those will fit in to the 61x head and have the angled injector thread with the correct placed hole for the GP. But these are 76 hp only in the 616 4 banger.
I have to check the part number of these.

The radial bores on the lower end of the 617 952 PC are 2.5 and 3.5 mm.
The "axial" is 2mm.
These bores are larger on the turbo than on n/a engines.

Tom
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  #38  
Old 11-29-2008, 03:58 AM
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here is a pic of a cross section of the OM617 and the OM603 prechambers. I added the red arrows to show how the air flow swirls upon entry to the prechamber.

Also here are some patent numbers to look up

US Patent 2,787,258

US Patent 4,347,814

US Patent 5,105,781

Note that in 89 ( the last patent listed) they changed the prechamber again and angled the injector in the prechamber. They redesigned the impingement ball again to give even more swirl to the air than it did in the OM603. These changes to the prechamber increased engine output by 4 hp and reduced the particulate emissions by 40%
Attached Thumbnails
Prechamber modifications-0m617_prechamber.gif   Prechamber modifications-0m603_prechamber_swirl.gif  
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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png
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  #39  
Old 11-29-2008, 03:07 PM
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Quote:
Originally Posted by tomnik View Post
sorry for my late and incomplete answer I promised.

I can't find the 606 PC drawing. I thought I had it but it is not in my PC box.
What I remember is that the inner volume was increased.

Here some part numbers:

engine PC

617 912 (80 hp) 615 010 0152
617 912 (88 hp) 615 010 0152
617 952 617 010 0352

606 962 606 010 0452

The main difference between 61x and 60x is the angled assembling of PC and injector. 60x have the thread for the injector (those with the low positioned thread) directly integrated in the PC, while the 61x use the extra thread ring for fixing the PC in the head and providing the thread for the injector.
Plus the flatted ball is deflecting the incoming air to one side to give an oriented swirl flow, corresponding to the angled injector. Two different systems that could not be mixed (in my opinion).
Further the hole for the GP is on a different position and also the axis of the ball.
The big exception is the intermediate PC design of the MB100 (light truck).
Those will fit in to the 61x head and have the angled injector thread with the correct placed hole for the GP. But these are 76 hp only in the 616 4 banger.
I have to check the part number of these.

The radial bores on the lower end of the 617 952 PC are 2.5 and 3.5 mm.
The "axial" is 2mm.
These bores are larger on the turbo than on n/a engines.

Tom
Lots of good information!!!! I ordered the patents today to add to my reference file.

The angling of the injector is very interesting and makes sense. Looks like they are using the injecting fuel to aid in the swirling.

I like the concept of patent # 4193379 (www.uspto.gov) It would definitely breath like I would like, but the quality of the injection would have to be a lot better, (finer atomization)

It sounds to me that the MB100 PC would be a good starting point if it will fit in the 61X head as described. It has the angled injector, the ball flat is clocked to the 60X (latest position), and the glow plug hole is right. All that is left is the PC volume, burn tube ID, and the burn hole IDs.

I would not let the 76hp rating of the engine discount the updated features of that PC. One limiting difference would be the PC and burn tube volume compared to the 60X PC, but to a point we are limited to what the cylinder head PC bore will allow.

Do you think you can get a PN and specks for the MB100 PC?
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  #40  
Old 11-30-2008, 05:26 PM
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The MB100 PC is 14 mm (lower part into the head) while the 617 PC is 16mm!!
The MB100 I have on my table, the 16 mm comes from the drawing. Please check.
Things get complicated.
The upper part of the PC could be exchanged. Some PC are welded some are secured with a 2x5 mm pin.

Tom
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  #41  
Old 11-30-2008, 06:43 PM
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This is all very interesting.. one question though:

If MB found an increase in efficiency going from prechamber to swirl chamber, why not scrap the PC altogether and machine a swirl chamber to go in the prechamber's hole in the head? Yes, I understand this is more work. It seems the modified PC diagram depicts a compromise between prechamber and swirlchamber.. why compromise?
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  #42  
Old 11-30-2008, 07:20 PM
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Quote:
Originally Posted by tomnik View Post
The MB100 PC is 14 mm (lower part into the head) while the 617 PC is 16mm!!
The MB100 I have on my table, the 16 mm comes from the drawing. Please check.
Things get complicated.
The upper part of the PC could be exchanged. Some PC are welded some are secured with a 2x5 mm pin.

Tom
Yep, the 616 and 617 N/A engines use the 14mm tube. The 617.95 (turbo) uses the 16mm. MB increased the wall thickness of the PC for the turbo motor due to increased stresses.

How dose the latest 60X PC with the angled injector compare to the 617 turbo PC. The burn tube OD looks big in the pictures I have seen.

The good news is I can use the MB100 PCs in my 616 with out having to modify the head.

I am not sure if MB opened up the burn tube inner dia with the increased OD (16mm). I believe their goal was to toughen up the PC it self. Boring out the ID would put additional stress on the PC and would undermine the purpose of increasing the wall thickness. My book calls out the burn tube ID for a 617N/A to be 7MM with a 14MM OD.

I am studying the patents and, at this point, think that MB angled the injector in the PC to accommodate placing the ball off center of the burn tube. The ball was placed off center to increase the balls influence on air flow during the compression stroke. If the injector was not angled to compensate for the altered ball position, the ball would not be as affective as a atomization aid.

The 4 HP gain from this off set ball design was achieved using stock fueling limits. They also found it encouraged a more complete burn, which means less fuel is needed to generate a given amount of heat,( better mileage). I would imagine that with a turned up pump, the HP increase would be higher over the previous PC design given the same amount of fueling, and therefore worth pursuing.

Since all the features we want are in the chamber, and that is made of the same piece of steal as the tube is, we can cut off the burn tube and weld on a 16mm one, ( not a good idea) or make a new PC with a 16mm tube. We could use the MB100 PC as a pattern, duplicate it but with a 16mm tube and use the ball. That is the easy part...

Now, any layers out there? The patent issue date I have is 1992. It is for the offset ball and angled injector, which is what we want to use for the new PC. I have had experience with this before, but I am not a layer, and will defer the legal implications of duplicating the latest PC features.

What is the PN for the MB100 PC?
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  #43  
Old 11-30-2008, 07:36 PM
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Quote:
Originally Posted by GREASY_BEAST View Post
This is all very interesting.. one question though:

If MB found an increase in efficiency going from prechamber to swirl chamber, why not scrap the PC altogether and machine a swirl chamber to go in the prechamber's hole in the head? Yes, I understand this is more work. It seems the modified PC diagram depicts a compromise between prechamber and swirlchamber.. why compromise?
MB is a luxury automobile and by nature is supposed to be quite. IMO the flow restrictiveness of the PC causes a pressure spike at the first point of ignition that rises the air temp super quick. That promotes a single, complete flame front and reduces cold air pockets. (The nailing sound is created by a build up of fuel in cool air spot that ignites via an adjacent flame front or a sudden raise in temperature.)

I think it is a huge trade off. My intentions are to get the MB PC to breath like a swirl chamber. Yes it might certainly be louder, but I don't mind.
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  #44  
Old 11-30-2008, 08:45 PM
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OK, I'm with you there, screw the quiet. I do worry about using the existing PC for this though, mainly because even when you do open the thing up there still probably isn't going to be much swirl, less even... might get less efficient?
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  #45  
Old 11-30-2008, 09:02 PM
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I have had a thought for a while now for a high flow PC and after seeing the patents, I want to get some feed back on it.

The ball has been off set from the center line of the tube in an effort to create a better swirl in the PC which improved combustion. What if an auger was put in the burn tube to increase velocity and flow direction? A radical helix, like some mufflers use, could be designed and inserted in the tube. It's job is to spin the air as the air travels through the tube to the chamber. The chamber end of the helix would be positioned to direct the air toward the wider side of the ball / chamber, the intended flow direction created by the ball its self.

The helix would provide a hot surface in addition to the ball to aid in the atomization of the fuel that is not burned by the time it gets to the tube.

It could also help isolate the acoustical pressure (shock) wave from the main combustion chamber (piston and rings), but if it needs to be too coarse of a pitch it probably would not. (just a thought)

It might work better with the standard 617.95 (centered ball) PCs because there would be a more even flow around both sides of the ball as apposed to the new design where the ball to wall clearance is grater on one side.

There are some issues that I can see with assembling the helical PC, and I have not totally thought out all the pros and cons of the concept, but I thought I would accelerate the process by throwing it out for everyone to comment on.
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