Also false information. Its known as "understanding what I'm doing first", compared to your method of "randomly screwing around with things and hoping it works".

You've got nothing worth knowing.

Also false. If you actually take the time and effort to read, you will have seen this:
"The pump can only be properly calibrated by a Diesel injection specialist on an injection pump test bench, this is not intended as a DIY at home pump calibration guide."

My document is not a guide on how to adjust anything, its information on what does what so that people wanting to adjust their pumps can do so without jumping in blindly. Its up to them to determine if they actually understand what they are doing. Counter to your beliefs, I have not received ANY negative comments about my document.

Unlike you, I don't lie and screw people over for a profit.

Pray tell, whats your excuse?


Which can be done identically using the external throttle stop screw, a 1 minute adjustment vs your method of repeatedly opening the governor cover.

Sorry, that is false.

Also incorrect. The main governor spring is what controls that, and adjusting it allows the possibility of overspeeding the engine.

josha, if you're interested in adjusting the pump, take it to a professional shop and ignore OM616's attempts to take your money from you. His shadetree techniques have no basis in reality.

Why do threads always turn into arguements? Arent we all here for the same thing? more power? some might care less about their engines than others or wont more power than others or even more power in different parts of the power band, but in the end why cant we all just get along and burn some coal?

Can we break away and talk about pre chambers for a minute? I have yet to pull them so i have not put my hand on one yet so i may be a bit ignorant of what i am thinking but open them up how? wouldnt that severly comprimise cold starting (not that i care much just wondering).

No, actually with the ability to fill faster, there will more air jammed in the Prechamber at cranking speed, so the temp will actually be higher.

Once the engine is running, from the simulator tests I have done, it appears that about 75%, (at best), of the cylinder gasses make it into the Prechamber before injection below 2,000 RPM. Above that, the VE of the Prechambers really start to fall off, which generates incredible non productive pressures and temperatures in the cylinder, before injection.

The holes in the prechamber were calibrated to meet the requirements of MB, and as you know they had high performance in mind when they built the 616. The per puss of the prechamber is to reach and sustain a higher pressure in the Prechamber during combustion, allowing the pressure and combustion to sustain after the cylinder pressure has dropped below that which encourages continued complete combustion. Basically, they make it possible for the engine to rev. Again it is a balance, I’ve opened up the holes without adding fuel and found quieter operation, more torque, and the high rpm EGTs went down, but I am sure that my emissions have also increased.

If you add more fuel, you generate more gasses, and if keeping with MB's calibration in a concern, the holes should be increased to allow the additional gasses to get to the cylinder and perform work, instead of just increasing pressures inside the Prechamber.

Additionally, with the turbo you are increasing the amount of air that is in the cylinder. The 616 Prechambers are calibrated for NA cylinder VE.

Crudely put, the Prechambers determine how fast the engine will rev at full power, so they can be opened up until your desired max speed is the fastest it will run. With the additional fuel and boost, you can open them up quite a bit and still be on the conservative side of the stock pressure differential.

. Um.. drill bit?

Sorry, dishonest "business" tactics tend to flare me up.

The prechambers are not a restriction to performance. Dozens of people have made over 100hp/cylinder without any need to alter them. Enlarging the orifice bores will only produce poor atomization of the hot fuel mix.
When you get over 400hp, then you should consider altering them. Until then its just tossing money out the backyard window.

You forgot to mention that it will also reduce air velocity and swirl, which significantly reduces combustion efficiency.

And you pretend I don't have real-world experience.

That is completely by design, thats why they are called precombustion chambers. Allowing more air than absolutely necessary into the PC is completely pointless since the resulting pressure inside is uselessly pushing on solid metal instead of the piston.

That is false. Combustion velocity of the fuel is what determines the maximum engine speed power can be produced.

As stated before josha, ignore people's attempts to take money from you for nothing, or in this case, simulated results.

The material is tuff stuff, and the holes are at an angle. The last ones that I did I milled a slot from the right hole, all the way across to the left hole.

One concern about just drilling the holes is that the webs between them will get real thin the bigger the holes. I was concerned that the thin webs would burn like the thin edge of a valve will.

If you use a carbide drill, make a fixture to hold them securely and at the correct angles, and use cutting fluid you should do just fine.

Jeemu, drilled his Prechambers so it can be done.

om 616 i appreciate you being helpful, we have very good bits at the shop i work at i should be able to make something work if i ever get around to it. Forced why does it always seem like instead of helping people you critize everyone?(barring that very nice ip rightup). You seem very knowledgable but you would rather talk down to people then help. Is there any evidence opening the chambers will not help? It seems logical kinda like opening up the gap on a spark plug, more mixture will be exposed to ignition sooner. I might be wrong but it sounds logical. Hell even 5 more horse in a 616 is gold...

Your 82 should have the up-rated prechambers with the swirl bar that goes across the prechamber and is pressed into both sides, as apposed to the early ones that have a toung type thing sticking out of one side.

The up rated prechambers are stronger and the swirl bar can be marked for indexing and removed. In the middle of the swirl bar is a ball with a flattish shape on the bottom. The bars are clocked so the flat is angled to direct the flow of gasses as they exit the burn tube and enter the prechamber proper. You can reinstall the bars so the angle is grater.

With the holes enlarged, there will be more gasses entering the prechamber over the same period of time, so the velocity will be grater as well. The increased velocity will react off the angled ball and a better swirl will result.

I am designing a prechamber that is tuned for power, based on tests performed on a mock up engine, (the simulator), which is actually one cylinder of a 616, that has been instrumented to measure pressures in the cylinder and prechambe at the same time for comparison.

Thas an extremely poor thing to do.

Yes, after he was making over 500hp from 2.5L.

Please don't.

Because many people say ignorant things that need to be corrected. Otherwise they will continue to give out very poor advice and people will do damaging things to their engine, such as he is trying to convince you to do with your prechambers.

I have already posted that several times. The Finns, the people that pioneered and continue to pioneer this field, don't mess with them until they are producing over 200Hp/Liter.

G@s engine analogies don't apply to diesels.

Altering the prechambers as he has described will reduce power, not increase it.

Again, a poor suggestion.

Opposite actually, velocity is reduced. Only pressure is increased.

Oh, you have a multi-million dollar R&D department like Mercedes did when they designed it? Sweet, lets see it!

What, you find it distasteful that I'm being honest and not trying to take your money?

Would you prefer I agree with him that blindly hacking away at your engine is a good thing???

No just processing. No one is trying to take my money. I am confused on how allowing more air in/out and/or fuel out would not improve the performance. I understand mb did it the way the did for a reason but they also left it na for a reason, set the pump the way they did for a reason, and yet we throw all that out the window why not look at the pre chamber as part of the injection system to find more efficiency? i realize the finns dont touch it but why?

josha37 (From PM) "So with pre chamber modification why not just remove? make it direct injection just like all newer diesels and save the headache? Might be a dumb question but sounds plausible."

I've cut the ends off of some Prechambers to see how close to direct injection I could get, but I am very concerned that the concentrated heat exiting the burn tube directly onto the piston would burn a hole in the piston is short order, so I have not tried them. I don’t think the boundary layer will be sufficient to protect the piston. I gave them to a friend that has been helping me in this effort to try, he volunteered his tired 616 for the cause.

The concept is more what I am looking to achieve, an external combustion chamber. I like the slot because it allows more flow than stock, still presents some restriction with the additional combustion gasses, and fans the heat over the top of the piston instead of directly onto a concentrated spot.

Small steps.

I have a tired old 616... hmmm...