Stock injectors are just that... stock. For the 617-95X the injectors are not really the bottle neck to higher performance, but they can be manipulated to give some gains. The first change is usually to change the stock nozzles from the SD241 to the SD265 found in the 60X engines. It's what is recommended by MB IIRC. They also give a bit better idle. The real only change I've found that will give a bit more HP may be the VW/Audi AAZ injectors found in the 1.9 VW diesels (canadian only versions). This is not a TDI engine, and the nozzles must be changed to MB nozzles.
PLEASE NOTE- there are mods you can do to the IP that will give much better HP gains for you efforts, and a EGT gauge is always the first step in seeking more HP.
Here are some other threads
Fuel pumkin warning (http://www.mercedesshop.com/shopforum/showthread.php?t=215955)
Nozzles or? (http://www.mercedesshop.com/shopforum/showthread.php?t=217576)

I have a TDI that is running a set of special Bosio injectors made specifically for the TDI. I am aware that Bosio also makes IDI injectors that are compatible with VW/MBZ applications. Does anyone know about these?

I have a TDI that is running a set of special Bosio injectors made specifically for the TDI. I am aware that Bosio also makes IDI injectors that are compatible with VW/MBZ applications. Does anyone know about these?


If you do a Google type internet search you will find other forums and comments on Bosio nozzles. From what I have read people are happy with them and they fell there engine runs better and the have a little more power. However, for MBZ the nozzles were $37 for 617 turbo engines and that was the price last year about this time I do not know what the price is now.
For myself I prefer something more economical but still good quality. I bought German made Monark spray nozzles from C Sean Watts. I have not installed them yet as I have not hat time to do so. They are not extra performance nozzles but I have read that they are quieter at idle. Some other members have done the installation and are happy with them.

In the trucking world, many guys have their injectors extrude honed for better spray characteristics. These are multi-hole direct injection setups though. I've never seen the tip of a MB injector so I don't know if extrude honing would be applicable there.

In the trucking world, many guys have their injectors extrude honed for better spray characteristics. These are multi-hole direct injection setups though. I've never seen the tip of a MB injector so I don't know if extrude honing would be applicable there.

They look like any other Bosch IDI nozzle, flat face, single hole.

Also in consideration are GTD nozzles from the 1.9L 90HP TD (VW) sold in Canada. These have 2 seperate springs, one for a pre-injection and another for the actual injection. They would make idle MUCH smoother.

Also in consideration are GTD nozzles from the 1.9L 90HP TD (VW) sold in Canada. These have 2 seperate springs, one for a pre-injection and another for the actual injection. They would make idle MUCH smoother.

Those are the AAZ injectors MTU was talking about.

I have a TDI that is running a set of special Bosio injectors made specifically for the TDI. I am aware that Bosio also makes IDI injectors that are compatible with VW/MBZ applications. Does anyone know about these?



Dieselgiant.com sells them. I will be putting them in my "85 300d

I may have a second set of the AAZ injectors. Stock pop pressure is 150, but I may have them set to 135, which is what stock MB injectors pop at. With the pressure level lowered I'm hoping for a longer duration of fuel, and more fuel being injected.

I think that will advance your timing a little as well since they will pop sooner.

I think that will advance your timing a little as well since they will pop sooner.
Actually, they will pop at the same time as stock injectors... correct? Since they are two stage that throws a little wrench into the mix. Of course I'll play with the timing. :)

Actually, they will pop at the same time as stock injectors... correct? Since they are two stage that throws a little wrench into the mix. Of course I'll play with the timing. :)

As I have been lead to believe, the steel lines flex when pressurized and absorb a minute portion of the pressure pulse's energy, thereby causing a slight delay in injection when the pop-pressure is raised. Depending on nozzle type, raising pop-pressures above documented/specified levels may have adverse effects, but this "theory" of sorts still needs further testing to be certain..

Actually, they will pop at the same time as stock injectors... correct? Since they are two stage that throws a little wrench into the mix. Of course I'll play with the timing. :)

OK, I was getting it mixed up. You're saying that the stock pop pressure of the AAZ's is 150 and you may have them set at 135 like the stock MB injectors so the end result is the same pop pressure before and after. Theoretically, your timing should be the same aside from the split shot issue.

stock pop pressire is 135PSI?

holy crap thats low....

stock pop pressire is 135PSI?

135 *BAR*

Thats nearly 2000 PSI!! :eek:

metric car= metric values

1 bar = 15.04 psi@ 0ft sea level

Opening pressure from the manuaL section 07.1-135; I jection pressure in bar posative for new injection nozzles 135-143. For used injection nozzles minimum 120 Note at the bottom; the differance in injection pressure of any 2 nozzles should not exceed 5 bar posative. (For nozzles DNO SD 2400, DNO SD 240 and DNO SD 240/.)
I used 1bar = 14.5psi;
135-143 bar = 1957.5-2073.5psi
12bar = 1740psi

1 bar = 15.04 psi@ 0ft sea level

Almost, 1bar=14.504psi.

I was chatting with a HD mechanic while on a jobsite about IDI performance and he suggested opening up the holes on the pre-chamber a small percentage. Has anyone heard or played with this idea?

Hello -

I've been away from the forum for a while, but with the spring weather I'm back to tinkering with the Benz. Anyway, I have a set of injectors with Bosio nozzles that I'm selling, check the Parts forum.

Thanks,
Eric

I was chatting with a HD mechanic while on a jobsite about IDI performance and he suggested opening up the holes on the pre-chamber a small percentage. Has anyone heard or played with this idea?


This sounds like a good way to melt a piston.

This sounds like a good way to melt a piston.

Explain...

Explain...

Regarding the design of the prechamber, I can only surmise that the holes are a specific size for a specific reason - namely to allow a certain quantity of burning fuel into the combustion chamber in a given time period- and to direct the flow of burning gasses.

If the holes were enlarged, burning fuel would be admitted to the chamber more rapidly than before - perhaps causing combustion chamber temperatures to rise too quickly - and increasing the risk of scorching/overheating the piston top.

Carried to the extreme, if the holes in the prechamber were merged into one large hole, would you not essentially have a direct injection engine?

[QUOTE=dawsonj3;1812524]Regarding the design of the prechamber, I can only surmise that the holes are a specific size for a specific reason - namely to allow a certain quantity of burning fuel into the combustion chamber in a given time period- and to direct the flow of burning gasses.[QUOTE]


I think when it comes to 'Hot Rodding' it's all about tweaking the manufacturers 'specific' designs to gain more HP. In the exerpt below, it leads me to believe that there is a small margin of tolerance to be played with when it comes to our pre-chambers, nozzles, and injectors. As Holeshotholset has pointed out this is where alot of truck guys start in their persuit of HP.:cool:

The following is taken from WIKIPEDIA on Indirect Injection:

An indirect injection diesel engine delivers fuel into a chamber off the combustion chamber, called a prechamber, where combustion begins and then spreads into the main combustion chamber. The prechamber is carefully designed to ensure adequate mixing of the atomized fuel with the compression-heated air. This has the effect of slowing the rate of combustion, which tends to reduce audible noise. In addition, it softens the shock of combustion and produces lower stresses on the engine components. The addition of a prechamber, however, increases heat loss to the cooling system and thereby lowers engine efficiency. In an indirect injection system the fuel/air mixing occurs with the air moving fast, and the fuel therefore need only move relatively slowly. This simplifies injector design and allows the use of less tightly toleranced designs which are simpler to manufacture and more reliable. Furthermore achieving the correct gas flow patterns in the swirl chamber is a relatively straightforward task.

What is the advantage to the 265 Nozzles over the stock 617 240 nozzles?

Better atomization, more modern design and no prespray hole to plug with carbon.

Regarding the design of the prechamber, I can only surmise

I wouldn't surmise or assume anything here. Engine modifications affect a large number of variables that are interlinked in fairly complex manners, so assumptions will only serve to dig yourself into a hole. If we just go based off of what we know, then we should be able to reason our way through these problems.

Is it possible to tell what type of nozzle is installed in an injector with out pulling it apart?

nope,
open it and check, then get it pop tested,

1 inj shouldnt cost alot to pop test

You can't tell exactly but you can narrow it down. Remove the injector and examine the pintle where it protrudes from the nozzle face under magnification. If you can see the pilot hole you have an early style nozzle.

nope,
open it and check, then get it pop tested,

1 inj shouldnt cost alot to pop test

I checked around here, before I decided to build a pop tester. IIRC it was about $10/injector to get them tested, more to have them balanced.

You can't tell exactly but you can narrow it down. Remove the injector and examine the pintle where it protrudes from the nozzle face under magnification. If you can see the pilot hole you have an early style nozzle.

I looked at a spare set I had and can only see the pintle. How big is this hole and is it centered or off to the side of the pintle?

A 240 will be more of a dull nub. A 265 will be a sharper point that sticks out further.

I may have a second set of the AAZ injectors. Stock pop pressure is 150, but I may have them set to 135, which is what stock MB injectors pop at. With the pressure level lowered I'm hoping for a longer duration of fuel, and more fuel being injected.
I've read that another person set the pop pressure at 175 bar and said that he had less smoke and a bit better response. He also said he had to advance the timing to 22.5 from 20 IIRC. With less smoke and no other changes this means he is getting less fuel but a better atomization of if logic follows. I still think I should go with a lower pop pressure. Thoughts?

I've read that another person set the pop pressure at 175 bar and said that he had less smoke and a bit better response. He also said he had to advance the timing to 22.5 from 20 IIRC. With less smoke and no other changes this means he is getting less fuel but a better atomization of if logic follows. I still think I should go with a lower pop pressure. Thoughts?

I'd say bad idea. Higher popping pressure is going to mean more fuel but also harder work on the pummp. Lower popping is going to mean poorer atomization. Why else would the NA have 135bar vs 150 on the turbo?

Why else would the NA have 135bar vs 150 on the turbo?

Compression/combustion pressures.

I'd say bad idea. Higher popping pressure is going to mean more fuel but also harder work on the pummp. Lower popping is going to mean poorer atomization. Why else would the NA have 135bar vs 150 on the turbo?
With all else being the same higher pop pressures would mean LESS fuel I think- but better atomization of the fuel, which is what I said earlier. Doesn't that follow? Lower pop pressure will mean MORE fuel, worse atomization. The nozzles are MB 265, so they are supposed to pop at 135- and atomize the fuel the same as stock injectors IMHO.

A higher opening pressure will result in less fuel injected earlier in the cycle and less injected later in the cycle.

It sounds like a good thing for economy, but nearly all diesels are somewhat lean from the OEM. It could actually lower economy in many cases.

I have found that more fuel injected with different pressures and nozzle configs can efficiency.

A higher opening pressure will result in less fuel injected earlier in the cycle and less injected later in the cycle. Also meaning less fuel in total is injected- is that also correct?

It sounds like a good thing for economy, but nearly all diesels are somewhat lean from the OEM. It could actually lower economy in many cases.

I have found that more fuel injected with different pressures and nozzle configs can efficiency.I want MORE fuel injected- so lower opening pressures sound like a option, especially with these AAZ injectors having a stock pressure of 150, and stock MB injectors opening at 135. I've read two differing accounts- one person said he got better response and less smoke with a higher pressure, and another guy said he got better fuel economy and less smoke with a lower pressure. Sounds contradictory, which is why I'm asking here for views and experiences.

With different pumps and calibrations I would venture a guess the injector settings that are reported as contradictory between cars is a given.

Even sticking DV's can change "when" the inejctor opens. Either early or late.

I am trying different settings now. using a test bench and soon in the engine testing to try and get a handle on what works best and why. It will probably all for not, but it is fun to play around anyway. (-:

Yesterday I messed with a few pressure settings and found out the volume test bench did not like the 145 bar setting, but really liked 135. This was using a 265 "type/style" nozzle.

Since diesel fuel is almost incompressible the amount of fuel injected is dependent on the effective stroke of the IP plunger as determined by the rack position. I'd have to dig out my bosch book to quote a figure, but the mw pump in particular is capable of delivering fuel far in excess of 135 bar. If I get a chance I'll run a fuel volume test with my pop tester 135 vs 150 bar. Say 20 strokes each so a significant volume is produced to measure. If someone else tries it first let us know.

Bob's the man. The thing I'm worried about is that I'll have alot of smoke at idle. I'll wait for your results and then send my second set off to Sean for the new nozzles and balancing.