How can you increase the volume without increasing the distance from the injector to the pintle?

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1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Changing the prechamber volume is going to change the compression ratio. Increasing the volume is going to drop it. IDI engines need a high compression ratio to aid in starting. Not to mention that dropping the compression ratio will drop efficiency too.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
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Any changes would be minute due to the restrictions of the head. An example of an option is changing the length of the tube.

MB increased the PC volume along with the burn holes in the 615 engine as part of an effort to address owner's requests for increased power.

Also, Remember I am thinking about a high boost application. More air allows more fuel, (providing the burn pressures are sufficient to support a good burn rate through the combustion cycle.

Generally speaking, lower compression allows for a higher boost pressure without creating access pumping losses during the compression stroke, we all know that. The concern is how low can it be before starting becomes an issue?

I was thinking out loud again.

The discussion is good, but in an effort to get back on track;

So, to recap the ideas for a new 617.95 PC

Can it be agreed on that;

1) The PC needs an insolating thermal coating to reduce the heat losses to the head.

2) Change the strait injector threads to the new angled threads, can use the new 616 PC for parts (if it is pined).

3) Use of the off set ball design change to go along with the angled injector will require a custom made lower half, as the 616 and 617.912 burn tubes are 14mm and the 617.95 is 16mm. Not a huge deal as the 616 PC can be used for a model and source for the new ball (again, if it is pined).

4) Increasing the burn hole area is justified by increasing boost and fuel.

Can we get the lower half of the new 616 angled injector so we can convert ours to fit the new angled threads or is it a totaly different injector body?

Sorry to introduce another tangential question, however I think it builds of one of OM616's points. In a certain recent aircraft diesel (the DeltaHawk), the compression ratio is so low that it won't start without the supercharger (the engine has a turbo and a supercharger)... This is a DI 2-stroke piston ported engine (no valves), so it is vastly different from the 617 in almost every way... But might the addition of a supercharger drastically reduce the compression ratio required in order to start?

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99 E300 Turbodiesel 100k

this is one of the best threads i have read in a long time.

So what happened with the PC mods?

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Aquilae non capunt muscas! (Eagles don't hunt flies!)


1979 300SD Black/Black MBtex239000mi
1983 300TD euro-NA. White/Olive Cloth-MBtex 201000mi. Fleet car of the USA embassy in Morocco
1983 240D Labrador Blue/Blue MBtex 161000mi

I spent last week converting my newly acquired 300DT to a four speed but need to pull the trans again and make a custom pilot bushing as the MB ball bearing one is too tight. I questioned it when I was putting it in, and should have played it safe. My friend's shop that I used, because mine has no room, has another car in the bay so I will have to wait until after the holidays to change it. That and it has been soooooo cold here that I don't want to go anywhere!!

Once I have the mechanically up to speed i need to instrument it and get base lines on the different measurement points.

After that, I will start turning up the pump until I reach a point where there is a need for more air. All the time with a consistent max boost level.

At this point I will start testing specific PC modifications and evaluate their effect on the engine. The first will be to open up the holes area by 5 or 10 %.

Depending on the results of that test I would construct an angled injector PC for the 617.95 and include any positive results from the previous tests in the new PC.

This is going to take some time as the weather here is horrible and with work and all. Everything that is to be done needs to be deliberate and well documented. The evaluation periods for each test may vary as well, depending on the initial results of each test.

I have been very pleased with the input from other members. It seems there is interest in this direction of research but the willingness to be a genie pig has not been strong enough to follow through. I bought this car specifically for this research.

My hope is by spring time we will have a good prototype PC for increased performance.

Hi,

I found an MB internal article that suggests PC mods in case of idle and partial load smoke.
See the pic below.
Increase the bore from 8 to 14 mm (616 and 617 engines) or from 12 to 14 mm for 615 engine.
As a result use the 617 017 03 60 plate (heat shield) with 10 mm inner diameter.
Further they lowered the position of the nozzle (closer to the ball) by 1 mm from 16.5 to 17.5 mm.

The second part of the page talks about shaking and poor idling quality.
The suggestion here is to change the tolerance of individual fuel quantity from (Bosch) 1 mm3/stroke to < 0.5 mm3/stroke (MB), IP bench setting.

Tom

Attached Thumbnails

 

Very interesting, When was this article published?

Keep up the great research!!!

I have seen the differing heatshields. Did they say there was a revision in the prechamber for this? Sounds like an easy mod for any machine shop.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

No, this was only when a customer claimed. Just the hard cases.
No revision of the PC. On top they say that it could also be mixed with stock PCs in one engines and that the original part number will be kept.
I am quite sure they did not inform these customers what they did in detail.
Yes, sounds like easy to do.

Tom

Was this accomplished with the 617 017 heat shield (being 1mm thinner) or do we need to machine the heat shield seat lower in the PC by 1mm of so?

Edit: Never mind, I see that the PC needs to be machined.

They are for Atomization, air to fuel mixture so they burn with less waste , and more efficiently, now the pump has to be set correctly also along with timing and valves, dumping to much fuel on top of a piston will only lead to washed out rings that leads to worn cylinders, pistons and poor compression. modifying prehamber is not recommended,

see post # 98.

It is made by MB!!
Only in hard cases individually when customer claims partial load smoke.

Tom

Care to explain that?

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42