MONARK vs. BOSCH INJECTORS - Page 2 - PeachParts Mercedes-Benz Forum

DIESELVOLVO · #16 09-30-2011, 10:02 PM

Do some searching on "swirl chambers". Just an amateur mech. here, but my theory about the lousy fuel mileage of mercedes diesels of this era is that the design of the prechamber wastes alot of the potential energy of the fuel. For example I have a volvo 264 with a six cylinder N/A diesel and a three speed auto tranny, 3.54 rear end, which gets about 29 mpg, has more power than any 240D I have ever driven and must be the same curb weight as a 240D. I think VW had a much better prechamber design with their swirl chamber than the mercedes "pinholes at the bottom of the tube design", just a thought.

vstech · #17 09-30-2011, 10:11 PM

from some reading I did in the past, one power improvement some vw crowds use is to install MB injectors in their diesel motors...
I'm fairly certain that the only reason WV gets better mileage is the mass of the vehicle... not the efficiency of the prechambers... put a 240 motor in a jetta/golf, and IF the springs can handle the weight of the superior engine, it'll get similar mileage.

DIESELVOLVO · #18 09-30-2011, 11:07 PM

I kinda expected a response along these lines. The engine in my Volvo IS made by VW. It is the same engine you are thinking of with two extra cylinders.

rickmay · #19 10-01-2011, 12:41 AM

Right now, I am guessing that I am old enough to father all those that responded to this thread. Have any of you owned one of these cars when new? Probably not, and I am certainly not trying to slam anyone...not my way. I owned a number of these cars, all of which I purchased new. I mention this only to relay my experience with these cars. I had an 80, 300D (at the time, I was 35+ years old), which typically got 24-27 MPG with combination driving (pedal ALWAYS to the metal), and on the road it was in the high thirties. Now, I am going to say something that I have seen knocked on the internet. My 300D, for example did great when I set the cruise at 55 miles per hour, and did not do as well at higher speeds. I have seen a number of people blast this "set it and forget it" routine, but thirty years ago, it worked. I don't know why. And, today, I drive my 240 at faster speeds without any real damage to MPG. Is it because it is broken in after 145,000? I don't know.

But, we are here today, and these cars have had verying amounts of use and abuse. I will say this, however, if your compression is into the 300 PSI + range, there isn't any reason it can't get great mileage. If you have this compression and are only getting 23-28 MPG on the highway, something isn't right. To me, this means that the pre-chambers have to be in good shape, the injectors should fire a narrow discharge at 1675 or more and be in good shape, the timing should be right on, and so on. It is clear that enthusiasts of this vehicle have adopted varying approaches based on the quality of car they bought, their pocket books, and their desire to improve the mileage. Perhaps, it is a cost versus benefit (return on investment they see) in making repairs to their cars. I would not buy a $1,500 clunk of a car and put a lot of money into it. On the other hand, I look at it this way. It is a hobby. Save money on gas (I traded grandpa's Grand Marquis and a dead MG for the car), and use the money to restore the car. In the eighties, to me, the car was a turtle, and today, I just want to keep up.

My thread wasn't meant for debate or to solicit comments that I am nuts. I have always looked at everything on the positive side, and ask why not. I love my 240, and want to do my best to make it what it was built to be. These are great cars.

So, back to the challenge. I cannot imagine that the prechamber on a 30 year old Mercedes is in great shape. I have seen comments that they can contribute to noise, and I would say, this car definitely throws out more noise than my other Ds that were new. This I am sure of. I know replacing the engine mounts will help a little, but my gut tells me that the noise is from something that contributes to my belief that the mileage can be boosted (it's not piston slap, as my compression is probably on the high side). I believe the upgraded chambers put in these cars at 81 or whatever have more of a "swirl" to them, but after 30 years, I cannot imagine finding something that looks new here. My gut tells me that this and injector condition and timing should be the focus.

I do not see a lot of discussion on prechambers on the net, because I am guessing that less than 10-20% have ever been pulled and inspected. It is, however, the heart of combustion.

And surveyguy, it seems you have reached the state of Nirvana, which few accomplish, so I applaud you. Since I am trying to do all the work on the car, being a 6 month old mechanic, I am taking the approach that less is better. It may take a year or two, maybe more, to reach any conclusions. I do know, however, that precombustion chambers in any online venue have been largely unexplored. G'day, all.

vstech · #20 10-01-2011, 10:00 AM

I think discussion on the PC's have been discussed some here.
please post all the info you get on them, all the learning we can get on here is a good thing!
I did read that MB upgraded the number or the size of the holes in the Prechambers in another thread somewhere. likely the performance section.
there are MANY posts about using bicycle tools welded to a slide hammer for PC removal.
also, it's been said that the Turbo PC's are larger than the N/A PC's...

charmalu · #21 10-01-2011, 12:54 PM

The following thread is also in the Wiki`s

http://www.peachparts.com/shopforum/diesel-discussion/207782-diy-617-9xx-prechamber-tools.html

There are some threads from the past of the prechamber balls falling off.

Here is a picture of what the Pre Chambers look like.
http://www.peachparts.com/shopforum/1550758-post33.html

HMMM... let`s see, my Dad is 90, you really must have some age to you.

Charlie

Stretch · #22 10-01-2011, 01:39 PM

I can think of at least one other person who thinks that pre-chambers should be pulled more often than they are.

http://www.peachparts.com/shopforum/diesel-discussion/156482-prechamber-removal.html#post1197199

and have a look at the prechamber ball fell off thread Charlie posted too.

You might also like to check out dieselkraut22's method of IP timing

Timing Injection Pump While Engine is Running - Benzworld.org - Mercedes-Benz Discussion Forum

treetrimmer · #23 10-02-2011, 07:55 PM

Quote:

Originally Posted by dieseldan44

I have both types of injectors in identical engines.

Monarks are quieter and smoother. Because they have no pintile holes, they are better for WVO.

The Bosch NOS France nozzles are louder, in a 'sounds more like a tractor' kind of way.

I've read this elsewhere, why do you suppose this is? (The Monarks being quieter). Just wondering what the technical explanation is, and if there really is an advantage to switching to them.

Also, what is the benefit of reaming glow-plug holes? I understand that you are removing built-up carbon deposits, does this improve combustion or just GP/starting performance? TIA.

DIESELVOLVO · #24 10-02-2011, 09:40 PM

Well I am not interested in who is old enough to be the father of whom. I do have an interest in real world experience which I do appreciate. I am glad there are folks joining this discussion with experience driving these cars from day one, that is always helpful. I wasn't trying to turn this into a Volvo vs. VW vs. Mercedes thread. I was just stating an observation and trying to make a comparison for the sake of trying to get a better understanding of the factors that affect fuel mileage in diesels in general. I happen to have experience with Mercedes and VW diesels and I have no interest in debating which is better I just enjoy analyzing the differences.

I am trying to get across the point that I have a vehicle that is almost identical in size and weight and aerodynamics (or lack thereof) to a 240D of the same era with similar gearing in the rear end and an auto transmission that gets much better fuel mileage than a 240D of the same era (a 1980 Volvo 264 powered by a 2.4 litre six cylinder N/A diesel made by VW). I have always wondered why it gets better fuel mileage with gobs more power, read: acceleration, than any of the 15 or so 240D autos I have driven. The main differences I have come up with are the Bosch rotary IP and the design of the precombustion chambers.

Now I know that pop pressures/timing/fueling are going to affect this, but I am just trying to look at basic design differences because there are always going to be slight variations in the performance of these cars after all these years that have to do with wear of the components in the fueling/timing systems.

compu_85 · #25 10-02-2011, 10:01 PM

Quote:

Originally Posted by vstech

from some reading I did in the past, one power improvement some vw crowds use is to install MB injectors in their diesel motors...
I'm fairly certain that the only reason WV gets better mileage is the mass of the vehicle... not the efficiency of the prechambers... put a 240 motor in a jetta/golf, and IF the springs can handle the weight of the superior engine, it'll get similar mileage.

The MB injectors are a bit bigger than the VW ones... more fuel = more power.

I'd love to do an apples to apple comparison.

This document describes why VW went with swirlchamers not prechambers: http://eva2.homeip.net/15D-SAE/15dsae.pdf

-J

DIESELVOLVO · #26 10-02-2011, 10:10 PM

Quote:

Originally Posted by compu_85

The MB injectors are a bit bigger than the VW ones... more fuel = more power.

I'd love to do an apples to apple comparison.

This document describes why VW went with swirlchamers not prechambers: http://eva2.homeip.net/15D-SAE/15dsae.pdf

-J

Thank you, I love stuff like this...Will be reading for a while now....

1980sd · #27 10-02-2011, 11:22 PM

Quote:

Originally Posted by compu_85

This document describes why VW went with swirlchamers not prechambers: http://eva2.homeip.net/15D-SAE/15dsae.pdf

-J

Because it's not as smoky and noisy

Benzbeliever · #28 10-03-2011, 10:13 AM

Having seen the spray patterns of both the bosch 240 nozzle and the monark 261 nozzle I would say the 240 nozzle makes a wider spray pattern. The 240 nozzle also atomizes the fuel better. All the spray patterns of the monark nozzles I have seen are relatively narrow and somewhat larger droplets. I have gone back and forth on which nozzle I like more. Currently I'm back to the 240 nozzle mainly because they throw a finer mist than the 261.

The pintle hole clogging can be an issue over time for those running wvo. I suggest anyone running wvo pull and test their injectors every 25k miles no matter what kind of nozzles you run.

I haven't watched my mileage close enough to see which nozzle gives better fuel economy but I would assume it is the stock bosch 240 nozzle because of the finer mist while pop testing. There also seems to be less smoke at WOT with the 240 nozzle.

If you have your injectors out you can look down into the prechamber with a flash light. You can only see the top half of the prechamber and ball but they always look really clean. From the pictures I have seen of removed ones the bottom of the prechambers and holes look really clean. I think there is soo much heat and pressure in there that there's no way for carbon to build up inside of them. Some does build up around the glow plug hole but not where the glow plug protrudes into the prechamber.

I saw a hypermiler with a geo metro at the Soul West Energy Fair that was getting 100 mpgs. He had chopped the roff 6-8", put a belly pan under it and taped/ bondoed anything that would catch air. You could get close to 40 depending on how drastic of measures your willing to take. I would look at sheding some extra weight. Lots of it...

vstech · #29 10-03-2011, 10:39 AM

yeah, hypermilers are crazy with mods to their cars... some totally block off the airflow through the radiator requiring frequent stops to keep the car cool... roll pans, tail fins, side skirts etc all help reduce drag. mirrors, door handles, some have tinkered with dimpling the skin like a golf ball to promote air movement ... I'm ok with 27ish...

funola · #30 10-03-2011, 10:49 AM

Quote:

Originally Posted by Benzbeliever

Having seen the spray patterns of both the bosch 240 nozzle and the monark 261 nozzle I would say the 240 nozzle makes a wider spray pattern. The 240 nozzle also atomizes the fuel better. All the spray patterns of the monark nozzles I have seen are relatively narrow and somewhat larger droplets. I have gone back and forth on which nozzle I like more. Currently I'm back to the 240 nozzle mainly because they throw a finer mist than the 261.

The pintle hole clogging can be an issue over time for those running wvo. I suggest anyone running wvo pull and test their injectors every 25k miles no matter what kind of nozzles you run.

I haven't watched my mileage close enough to see which nozzle gives better fuel economy but I would assume it is the stock bosch 240 nozzle because of the finer mist while pop testing. There also seems to be less smoke at WOT with the 240 nozzle.

If you have your injectors out you can look down into the prechamber with a flash light. You can only see the top half of the prechamber and ball but they always look really clean. From the pictures I have seen of removed ones the bottom of the prechambers and holes look really clean. I think there is soo much heat and pressure in there that there's no way for carbon to build up inside of them. Some does build up around the glow plug hole but not where the glow plug protrudes into the prechamber.

I saw a hypermiler with a geo metro at the Soul West Energy Fair that was getting 100 mpgs. He had chopped the roff 6-8", put a belly pan under it and taped/ bondoed anything that would catch air. You could get close to 40 depending on how drastic of measures your willing to take. I would look at sheding some extra weight. Lots of it...

I thought I've read that Bosch no longer makes injectors with the pintle holes, so you will only find them in old injectors or NOS.

Regarding the pre chambers, though I have never removed one, my thought is the same as you described. It's a hell hole in there with high pressure (with engine in proper running order) that it keeps itself clean like a self cleaning oven. The only thing that wears that I can see is erosion of the walls and the 6 or 7 holes slowly getting bigger. If they need to be inspected or replaced often, why didn't Mercedes put it in the maintenance schedule?