Monark injector nozzle results
 

Took a while to get the Monark injectors built as I was busy with work and other projects. The 760 sat dead for about the past 6 weeks with the injectors out of it. Finally got them put together over the last two weekends. Set all 6 to ~2400 PSI breaking pressure and got them installed Monday night. The results so far have been excellent. The car did not have more power immediately -- without changing anything else, the only effect of the injector nozzles was smoother/quieter running, easier starting, and no smoke at all. Power was about the same. This is relative to new Bosch injector tips, not worn ones. The improvement in running and driveability was noticeable.

Today I got around to replacing the transmission fluid and once that was done I was ready to try putting some additional power down, so I turned the pump up. The major difference with these injectors is they are able to flow much more fuel and produce a huge amount of power with no smoke. I turned the fuel quantity screw in all the way until it bottomed against the protective sheetmetal collar that prevents it from being screwed in too far. With the previous injectors (new Bosch 293s), turning the screw in that far resulted in large amounts of black smoke. With the Monarks, there is still no smoke and the power is remarkable. The car now can smoke the tires through first gear and spin them again in second. In the rain even third gear is dangerous and first and second are almost unusable unless the pavement is perfectly smooth.

I am going to cut the collar off the fuel screw and experiment with turning it in further still. Already this change has had the effect of making the car feel like it is 1000 lbs lighter. Highly recommended.

So these are the 273s correct? Pop pressure is where I set mine to as well. I'm quite happy with the results. Sounds like its time for a bigger turbo!

What do you have in it for a clutch?

Jason

Right, the Monark equivalent of the Bosch 273, the part number ends in 138. I posted the complete P/N somewhere on here a while back. Very pleased with the performance. It does need a larger turbo now, as well as other stuff to bring it all up to the same level -- probably should do a D24 intake or at least eliminate the boost dump valve, plumb an intercooler, larger exhaust and someday a pump from Giles. Picked up a 1983 D24T pump from the wrecking yard a few weeks ago (the best ones, the only year for the turbo pump with no EGR or altitude compensation junk on it but with the manual shutoff lever) and will send it up to him sometime when I've got the funds.

Exhaust currently is the stock size with both stock mufflers removed and one straight-through muffler at the rear. Quite loud, louder than I want it really since it attracts too much attention, but it sounds mean. I think there is still some restriction from the small size of it, since the motor seems strongest from 2500 to around 4000 rpm, but then still begins to run out of breath as you approach 5000. From a rolling start in 1st, most of the time it is a little slow to pick up but then once the tach hits about 3000 it often breaks the tires loose! The M46 has a very short first gear which is part of the reason for that -- I think a taller first would be better, since it runs out of revs very fast in first if you launch hard. Does do nice brakestands now though. :D

Jason, what is the power band on yours like now that you have a big turbo and exhaust on it? Probably a little doggy below 2000 but then strong right up past 5000? I guess you wouldn't know how it is below 2000 at WOT since your torque converter masks that... once you get the manual gearbox swapped in you'll see, these things do require a fair amount of shifting to keep them on the boil if you are trying to move fast.

Clutch is still the original one with 122k on it. Seems to be holding up OK for now but its live just got quite a bit harder now that I've turned the heat up on the motor (can't seem to keep my foot out of it :D). Trying to minimize the amount of abuse I give it but it's hard...

So you guys set your breaking pressure at 2400 psi (~163 bar)? I've read - somewhere - that the greater you set this value the longer it takes the injectors to inject, thus retarding the injection timing. Is the idea here that if you advance the pump timing you retard the injectors to "even out" the fuel delivery timing?

Or is setting a higher breaking done to achieve a better fuel atomization?

Right, that is certainly true, and I suspect that in addition to retarding effective in-cylinder timing the higher breaking pressure also causes less total volume of fuel to be injected for a given setting of pump piston travel (aka the "smoke screw"). Both of these can be compensated, by altering pump timing and increasing injected quantity by turning in the screw.

Better fuel atomization is the intended result, and there is a reason that in the case of our modified engines the normal TD setting value of 155 bar might not be high enough. Part of my rationale for running the higher injection pressure is that ultimately this engine will be ending up with higher in-cylinder pressure right before the moment of injection, due to increased airflow and manifold pressure. The combination of the upcoming changes -- D24 cam with earlier lift and longer duration, D24 intake that flows more air, larger turbo/increased boost, intercooler -- will all ultimately have the effect of cramming more air into the cylinder, and when it is compressed it will mean that there is considerably higher pressure in the combustion chamber for the injector to overcome as it begins to spray the fuel in.

You want the pressure differential to be a given ratio for optimum atomization. Making the fuel/air pressure ratio greater (as in higher injection pressure at a given in-cylinder pressure) is fine for atomization, but increasing combustion chamber pressure without also increasing injection pressure is a recipe for compromised atomization, which leads to more smoke, less power, worse efficiency etc when running under boost. This is the same reason there are different specs for setting breaking pressure on D24T vs NA D24 engines. Higher compression pressure and more air volume requires higher injection pressure or else complete atomization will not occur. That is why you can run turbo injectors in a NA engine, but it is not a good idea to run NA injectors in a turbo car.

So, short story is that when I was building the injectors I anticipated the fact that in the future I intend to increase the amount of air and compression pressure in my cylinders, and figured I should therefore slightly increase the injectors' breaking pressure as well to keep their pressure differential closer to what was intended.

What he said^^^


Mine really picked up some low end torque with the addition of the NA manifold, but with the way the torque converter slips, I really cant tell how much of a difference there is below 2k rpms. The engine revs to 2k as soon as you step on the gas if you are taking off. The top end power difference with the larger turbo is very obvious. Even before the intercooler, the NA manifold, or even the 2" charge pipe I had going into the front of the original manifold the top end power was much better. Mine was the same as yours, it fell off above 4k rpms. Now it pulls strong all the way to 5k untill it starts to defuel. I really think it has most to do with the tiny stock exhaust housing. Hell when I was pushing over 20lbs with the stock turbo it actually slowed down above 4k rpms... You could feel it plain as day! With the way the torque converter slips, my best power band is from 3500 to 5000, though I can build full boost by about 2800 or so once the converter is locked. I just adjusted the pump up a little more and burried the boost controller. I cant make more than 20 to 21lbs of boost, the trans just slips more. It will build more once the converter locks on the highway, but that doesn't do me much good. My clutch should be here any day...


Jason

I upgraded to the 275 nozzels and set to 2500 psi opening pressure. Great power increase but the timing is retarded too much ( I also ground the fuel collar off and turned the screw about 1 1/2 turns in) with the higher opening pressure. I set the pump before injector upgrade to .95mm . With the timing retarded it has hard warm start and rough cold start. I returned the opening pressur to 2200 psi now cold start good and warm start good. Does anyone have experance with how much to change the timing with the 2500 psi opening pressure. Or do I need to experiment? I do have a old Volvo diesel timing light but dont what to set timing to. Any advice would be great. I have plenty of injector shims of all sizes and the Volvo pop tester.

I think 2500 psi may be a little high if your not really turning the pump way up or trying for performance. I set mine at 2400 to 2450 which is just past the factory turbo diesel spec. I don't think I would reduce it to 2200, your just giving up better possible atomization and performance. At the least, I would set them at the top of the spectrum, which is around 2350 if I remember correctly. Right now, my timing is set at 1.00mm and starting/performance is better than it was with the stock worn out injectors and timing within factory spec. You will have to experiment with the timing as every engine is different, pump wear and other factors will contribute to how it runs too. I would start at around 1.0mm and go from there, once you set the injectors up a little higher.

Jason

I'm planning to give these nozzles a try. To repost your part # from the other thread, it's Monark 039 305 138.

It looks like MercedesSource has a pretty good deal on a pop tester for $179 also: http://mercedessource.com/node/5180

It looks like something that could be homemade for under $100, but I'm kinda leery to do home experimentation with something so potentially dangerous as 2400psi diesel fuel.

Are you certain that the increased pop pressure causes a significant change in timing and injection quantity? This is a positive displacement pump, and diesel fuel is relatively incompressible. The timing specs on the D24 and D24T are also the same, despite the differences in pop pressure.

The added pressure wont have much difference on quantity, but can affect timing to some degree. I don't have a number as far as extra mm needed per 100psi increase or anything, but just from tuning experience they do like more timing with the higher pop pressures. If you stop and think how the pump works, it injects fuel based on the rotation of the pump since the cam plate drives the head/rotor assembly. While the diesel doesn't compress any measureable amount at these pressures, the pump does have to build more pressure to open the injector. To build more pressure, the rotor in the head will have to travel slightly further before that pressure threshold is reached. The slight difference in plunger travel equates to some degree in rotational movement of the pump shaft. Advancing the timing offsets that difference. I'm still very happy with my 273 nozzles I got from vwdieselparts.com. They are the chinese ones but are great quality. I've also built a set for Alex's car and they are running well for him too. I have had them in my car since last summer, and when I swapped the engine I checked them. Pop pressure was still the same and the spray pattern looked just as it did on install. They are selling for only $45 for a set of 4. He will sell you a set of six if you ask.

Jason

Sean Watts at Hessian Imports (hessianimports@bellsouth.net) apparently keeps the Monark nozzles which fit our D24Ts in stock, and quoted me just $19.90 each with free shipping (if paid via check or MO). He seems to be a regular on Mercedes forums, and appears to be highly recommended. I plan to buy a set for both my Mercedes 190D and the 760. Anyone else have experience with him?

Jason- The Indian Bosch nozzles sound like an excellent deal, but I'm *dying* to experiment with these Monark nozzles after all the amazing reviews I've seen online of them.

//edit: Nozzles ordered. Now I need to beg/borrow/steal a pop tester.

I got my Monark nozzles from Sean, he seemed very knowlegable and customer service oriented. Just retested them after about half a year, they still sprayed well, didn't leak or demonstrate any other bad behaviors, even after surviving a fire!

At the time I didn't have the $100+ to blow on nozzles. I kinda wish I would have bought the good ones now. Then again, I have had great results with my cheapo ones, the spray pattern is still great and the engine is running aweseom, so I can't complain. It would be interesting to swap them out to see if there is a noticable differnce.

Jason

I'd bet you could sell your newly rebuilt injectors with Bosch nozzles for more than it would cost to rebuild another set of junkyard injectors with Monarks. I'd be curious to hear if there's much difference. I found amazing reviews of the Monarks on VW and Mercedes forums, but most people were replacing old worn nozzles with them, not brand new Bosch ones so the comparison isn't very scientific.

Same thing that I did, going from 175k original nozzles to new. Naturally there was improvement!

Jason

Are these the Merc type injectors that everyone is on about? - Monark type heads.

http://www.hansautoparts.com/16TDMercedesInjector.htm

ps - how can you adjust the pop pressure on an injector and would the timing of the engine need to be advanced or retarded to componsate?

No, those are for Mercedes. The guy that operates that site is a known bad actor named Pete Rothenbacher who runs many sites under many different names (dieselvw.com, volkswaparts.com, hansautoparts.com, emiata.com, and a few others as well as an ebay store under the name "prothe"), all of them selling cheapo Chinese knock-off parts for VW diesels -- AKA, complete junk. His stuff has resulted in many VW diesels and TDI's biting the dust in both minor and major ways. You want to stay away from his stuff, no matter how good of a deal he seems to be offering.

Besides that, even if you are getting good quality parts, you do not want to put a Mercedes nozzle in your VW/D24T engine... they are designed for a different prechamber setup and will do serious damage if you match the wrong injector type with a VW prechamber. There is a reason there are different parts. If you want Monark nozzles, you should get the correct ones for the VW/Volvo application, meeting the Bosch DN 0 SD 293 equivalent spec.

All the info on the site you listed is wrong but somehow it gets repeated enough that people are starting to think it is right... Let me be completely clear so that nobody makes a mistake and damages their engine. The DN 0 SD 265 spec is for MERCEDES and must not be used in a VW engine for any reason!

Suspect parts!!!
 

V8Volvo - thanks for letting me know about the injectors, I was about to place an order for them!!
Im still keen on getting the new Monark injector tips/heads and maybe increasing the break point/pop of injector to get a finer spray pattern.
It would be great to get a link for a supplyer for the heads and instructions on how to increase the break/pop point of injector 155Bar>

Thanks again V8Volvo

Contact information for two reputable Monark nozzle distributors (MercedesSource and Sean Watts) are posted further back in this thread.

I have made contact with Sean - H.A.I and he is going to find trhe suitable Monark nozzles for the D24.
As soon as he gives me the information I will be ordering them and I will post part number for other to benifit.

Monark nozzle's from Sean - H.A.I
 

I have made contact with Sean - H.A.I and he is going to find trhe suitable Monark nozzles for the D24Tic.
As soon as he gives me the information I will be ordering them and I will post part number for other to benifit.

I'm currently building a pop tester so that I can baseline all of my injectors. Based on the following page from a Bosch Injection Pump manual, it looks like the max nozzle opening pressure for our IDI applied VE pump is ~5000 psi.

Attachment 183

This seems reasonable to me, given the pressure continues to ramp up to around 15,000 psi after the injector opens. I am planning on baselining all my injectors around 2800 or 2900 psi. I'll most likely set the timing to about 1.05 mm to start with, and then try 1.10 mm.

My goal is efficiency, not massive power production. I'm fine with losing 10% power output if my efficiency increases by 2%. I really want to break the 40 mpg mark. I'll share my results with you folks.

There are likely diminishing returns to increasing pop pressures for a given injector/prechamber design. Have you found any convincing evidence that increasing pop to 2800-2900 psi will give you the results you desire? I will be interested to see your results.

Hi, I'm looking to rebuild my D24T injectors soon, and would be tempted to give the Monark nozzles a try. I'm looking to up the power a bit, but nothing too major - definitely no drag racing.

Are these the ones to go for?
http://cgi.ebay.co.uk/ws/eBayISAPI.d...=STRK:MEWAX:IT

Yes, the MONARK 039 305 138 are what we have had good results with.

Ok cheers. Sorry, I've got a bit lost reading this thread - these are the ones that have seem to give smoother running and less smoke even with the diesel screw turned up?

Also, is that a reasonable price?

I didn't notice any major difference, but was running stock tune settings anyway. The finish quality looked excellent. V8volvo has more experience with these nozzles than me. He gives them thumbs up, that's mainly why I bought them. Last year I bought them at $22 and $30, not incl. shipping (different suppliers).

d24 injectors
 

Interested to hear about it. Thanks.

injectors
 

Nice thread.
What is the main difference between v8volvo's 138 nozzles and the gtd ones?
I'd like to get a set of injectors built.
Car runs great but injectors might be getting tired a bit. I see smoke that developed slowly through recent years. Everything is well tuned. Injectors may need attention.
Idk what they are btw and mileage in them is unknown.