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  #151  
Old 08-06-2010, 01:44 PM
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Quote:
Originally Posted by babymog View Post
Would angling the holes in the pre-chamber create a swirl of air entering and gasses exiting and have any advantage?
I would think so. The holes, (really short tubes or bores) would need to be aimed up toward the chamber, but that would also direct the hot gasses directly onto the face of the piston where, even if the concentrated heat did not burn away the piston, I would think that the near supersonic gas jets would erode the piston face.

With the small holes dumping into a larger tube, that dumps into an even larger chamber, the velocity and direction of the flow of gases from the holes is very difficult, if not impossible, to control or maintain.

Additionally, really high speed flows do not like to change direction. Just like water, air's mass is sufficient enough to make it difficult to direct above certain volumes and velocities.

It would depend on how much air you wanted to pass through the holes, and, how quickly you wanted to do it.

From my perspective, MB's 616 with its 60 HP at around 4000rpm is the result of target based engineering. They met their targets, (noise, emissions, durability, etc), with a good degree of success.

I, on the other hand, have different targets in mind, and I am using the parts that I am stuck with to try to meet mine. It isn't that I think I know better than MB, I just have different goals.

Perhaps another way to picture my thinking would be to imagine wanting to transport 1000 lbs of widgets, in the trunk of a W123, and travel across the country several times. MB did not intend to have 1000 lbs of anything placed in the trunk, so it is no fowl against them that the bumper is on the ground.

So in order to be able to maintain the correct ride height, stronger springs and shocks will be required or perhaps even air bags might be a reasonable solution.

If I was happy with 60HP, I would not be messing with the thing, just as if one only had 100Lbs of widgets in the trunk there would be no desire to put in stiffer springs.

On the other hand, this could result in one of those educational moments. "Education is a progressive discovery of our own ignorance" Will Durant.

Proceed and be bold!
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  #152  
Old 08-06-2010, 04:50 PM
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If you look at the TDs, they are designed to carry 1000lbs, and unless the pre-chambers are different in Europe vs North America, I doubt that 60mph was the target. Probably more along the lines of BSFE and emissions, and emissions is why the 606.97x got the inclinded injection pre-chambers, I'm just not technically savvy enough to know why and how it affects the burn.

As far as angled holes, I was thinking in a way to create a rotation entering and exiting the pre-chamber, rather than a straight radial drilling. It doesn't seem like it would take much angle to create a swirl.
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  #153  
Old 08-06-2010, 05:24 PM
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As I understand it all 89+ mercedes diesels have the angled injection. I'd like to know how it helps emissions too.

-J
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  #154  
Old 08-07-2010, 12:50 AM
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Quote:
Originally Posted by babymog View Post
As far as angled holes, I was thinking in a way to create a rotation entering and exiting the pre-chamber, rather than a straight radial drilling. It doesn't seem like it would take much angle to create a swirl.
I agree. I would think you could create one heck of a tornado in there.
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  #155  
Old 08-07-2010, 01:00 AM
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Quote:
Originally Posted by compu_85 View Post
As I understand it all 89+ mercedes diesels have the angled injection. I'd like to know how it helps emissions too.

-J
My understanding of the angled prechambers is that the ball shaft was also off set from the center axis of the burn tube to help create a directional swirl rotation.

If I remember correctly, (I need to review this thread to be sure), the injector was angled to spray with the rotation, which I think would help the fuel travel with the rotating air, resulting in better distribution.

Also I can picture the nozzle getting fresher air rotating past it for longer because with the angled spray, fuel isn't necessarily blown and burnt up stream of swirl until later in the injection.

That is all I got.

Anyone?
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  #156  
Old 12-16-2017, 02:20 PM
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Update

I finally got a chance to put the "Big Mouth" prechambers in and I am very pleased with the results.

I should note one of the mods that I did to the burn tube was to taper the ID which had been done by another member over at STD, so these are a collaborative result lol.

When I first started the engine up with them installed it ran like crap, missing now and then at idle, ruff and smokey cold start up, and noisy.. I was not thrilled at that time. Keeping in mind that there was still air in the injector lines and the other member did state that after tapering the Burn Tube he had to advance the timing, I advanced mine as much as it had left which put it at 26*. After doing that, all the problems went away, nice idle, no smoke, and it even got quieter and had a nice light rattle like a real diesel lol..

I wanted to advance the timing more but would have to pull and re-index the pump, so I had to wait till I had time to do anything more. Thanksgiving gave me the time to take the car to a friends heated shop and I advanced the camshaft 10* before I went crazy with the injection timing. I drove it with 26* and the camshaft 10* ahead for a week so I could keep track of which mod did what.

Then I pulled the pump, modified the governor, and reinstalled it at 28*. I am very please with the result of all the mods. When I get a chance I want to bump the timing up to 29* and see how it does.

You can see in the pics why I call these the Big Mouth prechambers lol.. In addition to cutting our the three burn holes in the front and tapering the burn tube ID, I also opened up the ID of the injector heat shield seat to 14mm and instead of sinking the seat down, I back cut an angle bellow the seat to allow for better swirl a the injector. Doing that in addition to tapering the burn tube increased the volume inside the prechamber. I also installed the balls so the flats are on a slight angle instead of perpendicular to the burn tube.

I would call this set up a hybrid between a DI and IDI engine.

In addition to advancing the injection timing to 29* or 30* the next step is a bigger turbo and 10MM pump.
Attached Thumbnails
Prechamber modifications-prechamber-002-small-.jpg   Prechamber modifications-prechamber-004-small-.jpg   Prechamber modifications-prechamber-small-.jpg   Prechamber modifications-prechamber-006-small-.jpg  
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  #157  
Old 12-16-2017, 06:42 PM
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I opened my prechamber's holes up slightly and detailed it over at STD. My 0-60mph dropped from 9 1/2+ seconds to 9 flat with far less smoke and a better running engine. No other changes were made at that time.
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  #158  
Old 12-18-2017, 02:41 PM
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A+
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  #159  
Old 08-06-2018, 01:22 PM
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Has anyone else enlarged the prechambers of their 617a and if so what have you found?
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  #160  
Old 08-15-2018, 01:20 PM
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Quote:
Originally Posted by MTUpower View Post
Has anyone else enlarged the prechambers of their 617a and if so what have you found?
Captain America had enlarged prechambers for a bit and liked them. He blew the headgasket in that engine, but was also running a bunch of other hot stuff so it's unclear just what did it.

I'll be running modified PC's when I get mine back together.
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  #161  
Old 08-28-2018, 12:23 AM
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been running opened up PC's for a while but also a 8mm M pump and a HE221w so no comparison with standard and modified. i did have them in before the pump swap but i had a ported head and 221w by then so im not sure how much of the gain was them and how much was everything else. if i ever get the time i may go do some dyno runs at a shop near me. it would be interesting to try a few different things and see some actual number changes.
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  #162  
Old 09-02-2018, 07:38 AM
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Quote:
Originally Posted by R-3350 View Post
been running opened up PC's for a while but also a 8mm M pump and a HE221w so no comparison with standard and modified. i did have them in before the pump swap but i had a ported head and 221w by then so im not sure how much of the gain was them and how much was everything else. if i ever get the time i may go do some dyno runs at a shop near me. it would be interesting to try a few different things and see some actual number changes.
This is on a OM617-95X? What rpm do you have 13 psi boost? What is the upper limit of boost? 25? 30? More?
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  #163  
Old 09-04-2018, 04:51 AM
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if i brake boost i can get to 13 by 16-1700. its hard to say though since it pulls the torque converter stall speed to 2500+ ish once it gets enough boost to trip the alda(not counting the tires spinning the second boost hits). im running somewhere between 25 and 30lbs right now but i need a much larger turbo to properly use the 8mm pump.
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  #164  
Old 09-04-2018, 09:13 AM
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What about daily driving full acceleration? 10 psi by 2000? I think I'm going with a Holset HX30 super 6cm 44
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  #165  
Old 09-05-2018, 12:07 AM
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Originally Posted by MTUpower View Post
What about daily driving full acceleration? 10 psi by 2000? I think I'm going with a Holset HX30 super 6cm 44
I respectfully request that this topic be discussed in R-3350's thread on his engine build.

Thank you
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