Anyone ever thought of doing away with the precombustion chambers on a 5cyl 126 diese - Page 4 - PeachParts Mercedes-Benz Forum

gsxr · #46 10-08-2007, 04:08 PM

It's possible, but the cost and engineering involved would be insane. And the benefits would be, IMO, fairly minimal. You're better off just modifying the existing OM617 (intercooler, increas fueling, etc) or upgrading to an OM60x engine. Much cheaper, much easier.

gsxr · #47 10-08-2007, 04:12 PM

Quote:

Originally Posted by MBRO

As we are on the subject. My new w123 300TD was a taxi before I bought it (last week

), and makes horrible horrible noise compared to the 240D my father uses. The pistons are ok, not broken or anything (the former owner did the segments at a garrage, and i peeked to see what's inside the engine

). Do you think that valve adjustment and injector nozzle replacement will help? I also read an article on the internet that the precombustion chamber can be cleaned too.. Do you know how that is done?

Start with the valve adjustment, check cam timing & chain stretch and adjust with the offset keys, then set injection timing. If the noise remains, pop test the injectors, and make sure all prechambers are not missing the center spherical pin. Replace or rebuild any injectors that are not spraying properly. And set them to ±3 bar if possible. That, along with a healthy diet of Italian tuneups, should reduce or eliminate the noise over several thousand miles - the noise may not go away immediately. I'm assuming you are using a proper diesel-rated xW-40 or xW-50 engine oil, btw.

MBRO · #48 10-08-2007, 04:17 PM

Quote:

Originally Posted by Craig

Software = cheap

Hardware = expensive

I don't want to start disputes that are not constructive....but...
actually is the other way round...in most of the cases (automotive industry included).

Here for example, a Ford Fiesta 1.6 TDCI with 60 bhp is about 3000 euros cheaper than the same car with the same engine but with 80 bhp. (this was my closest examples, one of my friends in the lab wants to buy one and I have the price quotes on his desk

). Guess where is the difference? You are right, the difference is in the program loaded on the ECU. (the whole car costs about 10 000 euros).

But let this discussion end here, or let's start a different thread for this if there are more who are interested in this debate. We don't want to bore the others.

Please if you have, share the information regarding precombustion chamber cleaning...

pawoSD · #49 10-08-2007, 04:48 PM

Anything the average person thinks they can do to improve a MB engine will not improve it. Simple as that. The amount of research/development/testing that goes into their engines is astronomical. The result is a product as perfect as it can be. Boosting power with extra fuel/propane etc...will likely work, but lowers the engine lifespan. The engineers took all that into consideration.

Tymbrymi · #50 10-08-2007, 04:50 PM

Quote:

Originally Posted by gsxr

It's possible, but the cost and engineering involved would be insane. And the benefits would be, IMO, fairly minimal. You're better off just modifying the existing OM617 (intercooler, increas fueling, etc) or upgrading to an OM60x engine. Much cheaper, much easier.

As much as I would like to disagree (Computer Engineer here...) the above is really the most bang for your $$ method.

Converting an OM61x or OM60x to a DI engine would require:

A new head design to put the injector in the correct place for a DI engine, and to move the "squish area" to the proper place. $10k+
New pistons to reflect DI design principles. $2000
New injectors... could probably be retrofitted from other common rail diesels. Used + common rail pump, etc $1-3k.
A new computer controller + sensors + power electronics for controlling the injectors. Including at least a little time to reverse engineer sensors, etc ~$5k
Hours of trial and error to get the timing curve right (the timing on our engines is not static... as the engine RPM changes the timing changes as well...) and all those other silly little things. $$$$

I'm not going to tell anyone that it can't be done, but it would take probably greater than $20k to get something that would work even reasonably well (a million dollars is WAAAY too high though). Personally, if I was willing to spend $20k to make my MB faster I'd just get a CDI engine, reverse engineer my own custom computer, and drop it in one of my cars. That would probably end up costing the same, and I can still buy most of my parts from the MB dealer. However, I can get almost that same performance by just adding an intercooler, turning up the fuel (and/or getting a MynaDiesel pump), larger turbocharger, etc. to the IDI engine already on my car, but it'd cost quite a bit less

.

pawoSD · #51 10-08-2007, 04:53 PM

I'm sure programming a computer system to run a common rail injection system on an engine properly from scratch is just a bit more complicated than the average person could handle on their own....

Tymbrymi · #52 10-08-2007, 04:55 PM

Quote:

Originally Posted by pawoSD

Anything the average person thinks they can do to improve a MB engine will not improve it. Simple as that. The amount of research/development/testing that goes into their engines is astronomical. The result is a product as perfect as it can be. Boosting power with extra fuel/propane etc...will likely work, but lowers the engine lifespan. The engineers took all that into consideration.

I'd disagree with that. We can add things that they couldn't due to cost constraints (intercoolers). Turbochargers have also gotten more efficient over the years so they don't increase intake temperatures as much (equals lower combustion temps which means more power is able to be made before damaging engine). Adding these things would only get you about a 20-25% increase in power, but it wouldn't really decrease engine life in any noticeable manner. Adding 50-100% power gains... yeah, that'll reduce engine life. It will be fun until it blows though!

Tymbrymi · #53 10-08-2007, 05:02 PM

Quote:

Originally Posted by pawoSD

I'm sure programming a computer system to run a common rail injection system on an engine properly from scratch is just a bit more complicated than the average person could handle on their own....

In a year? Yes. Over 5 or 6 years as a fairly involved hobby... probably not as much as you'd think. Depends on how well documented sensors and whatnot you can find. Documentation is the hard part. The math to control the injections isn't impossible, its interpreting all the sensor information into what the desired duration, timing, etc that is the hard part.

MBRO · #54 10-08-2007, 05:05 PM

I am not suggesting converting the IDI engine to DI engine. What I am trying to say is that the engine should remain IDI, but the control of the injectors (new ones of course) can be made by an ECU and that shouldn't cost more than 1.5 k $ (mostly the manufacture of the commonrail. If there isn't one already on the market for a different engine. But if there is it would have to fit exactly. Here I mean the path to the injectors to match, and to be the same length and all that).

And I have to admit most of you are right. If you want to design a commonrail system to sell then it would take a lot of money and time. And that is just because it is not enough to make it work. The one who wants to design such a system must have in mind that there is a whole forest full of stupid drivers, and the system is not allowed to fail even in these conditions. But when you design something for your own use then the task is 99% simpler. Because you know what is in there and how to treat it right. Of course in the first 2 or 3 years there will be a lot of tweaking...but that's just plain old fun

#55 10-08-2007, 05:20 PM

Quote:

Originally Posted by Tymbrymi

I'm not going to tell anyone that it can't be done, but it would take probably greater than $20k to get something that would work even reasonably well (a million dollars is WAAAY too high though).

In the real world, $20 would cover about one man-month of engineering time. That might be enough time to prepare a conceptual study and come up with a preliminary estimate for the detailed design cost. Just the engineering (design only, not software) would cost several $100K, before any hardware is built. A million dollars is a pretty small project, if you are talking about anything that will go into production. You might be able to cobble something together yourself for $20K, if you don't count your time; and it might even run.

MBRO · #56 10-08-2007, 05:25 PM

Quote:

Originally Posted by Tymbrymi

In a year? Yes. Over 5 or 6 years as a fairly involved hobby... probably not as much as you'd think. Depends on how well documented sensors and whatnot you can find. Documentation is the hard part. The math to control the injections isn't impossible, its interpreting all the sensor information into what the desired duration, timing, etc that is the hard part.

Sensors and documentation is not a problem. (I am #2 in a company that among other things has some automotive projects on the roll, up to now we are developing a solution for monitoring diesel consumption so the truck drivers cannot steal from their bosses. We are talking about old trucks that do not have onboard computer that does that). An I think that in a sustained manner the ECU software can be written in under 3 months. The hard thing is completing the LUT (look-up tables). Those are some tables with values that are processed (almost all the time values from different tables are added) to calculate all sort of things. The formula to calculate is fairly easy (after you are familiar with the engine). But the values in those tables are the real hard thing to get right. (when you do a chip tunning, they don't rewrite the actual software, the just update those LUTs).

Besides the work, I am involved in academic research projects. One of those (that I am working now) is porting and RTOS (real time operating system) written by our lab director for DSP56307 to an ARM7 microcontroller (NXP LPC2294 and LPC2103 for those that are more curious). And that can be easy configured to control the engine. After all we are talking about events (injectors firing) that have hard time constraints.

Tymbrymi · #57 10-08-2007, 05:25 PM

Quote:

Originally Posted by MBRO

I am not suggesting converting the IDI engine to DI engine. What I am trying to say is that the engine should remain IDI, but the control of the injectors (new ones of course) can be made by an ECU and that shouldn't cost more than 1.5 k $ (mostly the manufacture of the commonrail. If there isn't one already on the market for a different engine. But if there is it would have to fit exactly. Here I mean the path to the injectors to match, and to be the same length and all that).

That is MUCH easier to pull off. Easy being relative of course

. I would actually recommend using the same injectors as they are designed for the engine... I would suggest finding some high pressure high speed solenoid valves to control the existing injectors through a common rail system (maybe through butchering of common rail injectors?). The pop pressure of our injectors is around 145 bar, so the common rail would have to run at about that pressure as well. Much simpler than the 2000+ bar pressures of a real common rail, but still not something to laugh at.

Tymbrymi · #58 10-08-2007, 05:28 PM

Quote:

Originally Posted by Craig

In the real world, $20 would cover about one man-month of engineering time. That might be enough time to prepare a conceptual study and come up with a preliminary estimate for the detailed design cost. Just the engineering (design only, not software) would cost several $100K, before any hardware is built. A million dollars is a pretty small project, if you are talking about anything that will go into production. You might be able to cobble something together yourself for $20K, if you don't count your time; and it might even run.

No argument for production. Especially with all the requirements of todays engines....

MBRO · #59 10-08-2007, 05:35 PM

Quote:

Originally Posted by Craig

In the real world, $20 would cover about one man-month of engineering time. That might be enough time to prepare a conceptual study and come up with a preliminary estimate for the detailed design cost. Just the engineering (design only, not software) would cost several $100K, before any hardware is built. A million dollars is a pretty small project, if you are talking about anything that will go into production. You might be able to cobble something together yourself for $20K, if you don't count your time; and it might even run.

If I am annoying you just tell me and I will stop this discussion. (I'm new here and I don't want to get banned or something

)

Let's do a price quote for the electronic hardware system:
PCB: 100$ to manufacture
Processor: LPC2294 = 50$ (or less). LPC2103 = 5 $ (but has limited resources)
Various components (quartz, condensers and others) = $100 (insane, but let's be generous).
Protection systems specific to engine environment (filters, high voltage protection and others) = $50
Power electronics (to actuate the injectors) = $ 50
Casing (resistant to vibration, and outside environment conditions, heat) = $200

So as a sum, the whole electronics involved should cost about: 500 $

And the software development costs nothing but time if you do it yourself.

#60 10-08-2007, 05:42 PM

You're not annoying me, and you won't get banned.

I agree that the electronic hardware is inexpensive, I was talking about the cost of redesigning the actual engine components (i.e., the head). I thought we were talking about converting from indirect injection to direct injection, which would require significant engine redesign. Just converting from a mechanical to electronic fuel injection system would require the installation of a fuel pump and a crank position sensor, in addition to the computer controls. I'm not saying it's impossible, but it would be a bunch of work.