Converting the multi-fuel to pure diesel...

[merlot566jka]

I wrote some stuff on the multifuel found in engineering text books... Posted pics of the head and chamber design as well.

I think the MAN engine/process has potential. With modern tools, I think power could be increased significantly without losing the multifuel capability.

I don't think converting it to diesel only, or LPG or changing it to run other fuels is a good idea. I mean, it was designed to run other fuels safely, so let's explore why it doesn't make more power from these fuels.

The compression ratio isn't an issue... As I recall the 6.2l has a comparable compression ratio, and it's a diesel only engine. (although I ran mine on transmission fluid once) sure a lower ratio will allow for more boost... But...

Boost could be a way to harness more power. The c and d turbos aren't designed to make power the entire range... And weren't really designed for power anyway. That could be a great starting point.

Injection pump timing could be another... How does the LDS465-1A make 50ish more hp than the ldt?

Injector styles? In Taylor's text, there are the examples of combustion based on types of injectors... This is based on diesel theory though... Not so sure that these examples lead to significant info in the multifuel. None the less, I am certain injector pattern and pop pressure will have an effect on power.

Engine design... Head flow, valve size, cam design... These are basics of power in any internal combustion engine. How do we know that the multifuel has been optimized in these areas?

Lastly, my big issue... Engine speed. To increase power we have to increase the amount of work over time... Or increase torque! So how is that done? More bang, or more rpm. The more times we make power during a set time the higher the average power... Translation, more rpm is more power. Even if we saw just an increase of 600rpm, we are talking serious changes in peak output (provided everything else is along for the ride... Turbo, fuel, cam, heads, crank, etc etc)
But who gives a rats arse about peak power? That doesn't mean anything... But higher average power through out the range is important.

Anyway, I'll add more tomorrow. It's past my bed time.

 

[deuceaid]

I would really like to understand exactly what is happening in the multifuel combustion chamber.

Your looking for post 12 of this thread,,,,enjoy!

http://www.steelsoldiers.com/deuce/73319-definition-multi-fuel-2.html

EDIT opps,,,looks like merlot beat me to his post...

 

[plym49]

I guess the corollary question is what it would take to convert a conventional diesel engine to hypercycle/multifuel. Pistons/injectors/pump timing?

 

[patracy]

I guess the corollary question is what it would take to convert a conventional diesel engine to hypercycle/multifuel. Pistons/injectors/pump timing?

Pistons with bowl/swirl design, injectors, angle of injectors, angle of spray pattern, injection pump that can adjust by fuel density.


Oh, and lots of money.

 

[Heath_h49008]

It is my understanding that the "cup"... actually the combustion chamber has a flame present at very odd times, or at least enough heat/time to ignite BEFORE normal diesel ignition would take place. The heat is transferred to the liquid via conduction from the wall, and the surface of the puddle is ignited at the time of injection/contact or very shortly thereafter.

Actual swirl and the bulk of combustion takes place at TDC when the quenched air volume of the cylinder is reduced, and that large volume of air is forced into and under the puddle via the combustion chamber ramp in the piston, mixing the compressed air with the already lit fuel, and beginning the power stroke.

This heating of the fuel allows for the effective combustion of sub-par liquids. Also, the slow heating process allows for the engine to "knock-free" in normal operation. The pressures before TDC... detonation... and other issues common to diesels and other engines where ignition occurs before TDC and peak cylinder pressures can happen on the upstroke of the piston. In gasoline engines, it indicates a lean condition and a detonation of the volatile mix rather than a slow burning. In diesels it is much the same... although the fuel air mix is not the issue, and it is considered a normal part of the design.

The reason Meth/propane systems shake the multifuel to bits is that early ignition. The mist/gas in the air charge lights at the same time as the surface of the puddle. and creates a massive overpressure too early in the cycle. I think the best description I heard was "I hit it for 10 seconds and thought the engine was coming apart." It makes sense... any significant amount of fuel/air ALREADY BURNING on the compression stroke would tend to do that.

I suppose we could do a little math and figure out what the cylinder pressure is at each degree BTDC and then find what pressure should light "normal" diesel and we can be certain the point the gas/fuel mix would be on fire.

Basicly, the Multi-fuel squirts in a puddle that gets pre-heated and set on fire, then "exploded" by mixing in the air and allowing combustion to take place. To put it another way... our engine is a daisy cutter... one that is dropped already on fire... and it is set off by the mixing charge allowing oxygen to hit ALL the fuel instead of just the surface. A two stage process instead of the diesel or gasoline engine which only has one.

I believe I'm describing this correctly, but please correct me if I slipped.

 

[Heath_h49008]

Pistons with bowl/swirl design, injectors, angle of injectors, angle of spray pattern, injection pump that can adjust by fuel density.


Oh, and lots of money.

Maybe not, the timing is easy with electronic engines. The chambers aren't that complex. And you don't need a spray pattern as much as a big ugly stream of fuel.

So what are we talking?

Pistons, injectors, programming and a fuel density sensor?

 

[patracy]

Maybe not, the timing is easy with electronic engines. The chambers aren't that complex. And you don't need a spray pattern as much as a big ugly stream of fuel.

So what are we talking?

Pistons, injectors, programming and a fuel density sensor?

Ummm, go study the cross section of a modern diesel engine and the cross section of a multifuel combustion area. You'll find a great deal of difference.

A modern DI diesel has the injector at a 90* angle in the center of the piston. The bowl also has a crown inside of it as well. The multifuel is an offset injector just touching the outside of the bowl. That's what promotes the swirl effect of the MAN hypercycle.

Pistons, injectors, heads, IP/or programming, automated fuel metering system, and money.

 

[plym49]

Your looking for post 12 of this thread,,,,enjoy!

http://www.steelsoldiers.com/deuce/73319-definition-multi-fuel-2.html

EDIT opps,,,looks like merlot beat me to his post...

Thanks, I had in fact seen that post a while ago, but it did not answer my questions.

I understand that we have some swirl going on. And I understand that we have some burning earlier on the compression stroke before the big bang occurs later - just before TDC, I presume.

1 - If there is burning earlier on the compression stroke, what is initiating the burning? How many degrees before TDC is there enough heat on an up and coming piston to produce enough heat for the burning to initiate?

2 - What is causing the main event, that is, the bigger bang? As I understand it, the injectors fire only once. Is it that the first part of the squirt just burns, but they keep on injecting, and later on there is even more heat/pressure so the burning mixture plus that which has not yet burnt ignites (tempting to say explodes, but it doesn't really, correct?)?

3 - Do the multifuel injectors have more duration in addition to earlier timing?

4 - Do the injectors spritz a variable pattern? Dribbley for the burning, and misting for the 'exploding'? Or do the mist (or dribble) the entire time?

5 - Speaking of power, all else being equal, a given amount of fuel in a given displacement cylinder at a given rpm will generate a given amount of power. Let's say that the volume of fuel is 'x'. In a conventional diesel, that volume of fuel - I assume - is being delivered in a fairly short window as a mist at a certain number of degrees BTDC. In an equivalent multifuel, that same volume of fuel is being delivered over a longer period of time, starting even more BTDC and ending at about the same number of degrees as before. Is that correct?

 

[exbrown]

One issue you may have if you convert to a spray type diesel injection would be the detonation of the fuel verse the burn of the current design. Allowing the fuel to detonate, as in a diesel, would add a lot of wear and tear on this engine. Even if the max pressure stayed the same, the pressure curve would be much different (steeper). By burning the fuel in a shorter amount of time, I would bet the pressure would be much higher.

 

[Heath_h49008]

True. The diesel would have to be injected much later so the flame propagation and pressure rise fell in the same curve.

 

[Heath_h49008]

Ummm, go study the cross section of a modern diesel engine and the cross section of a multifuel combustion area. You'll find a great deal of difference.

A modern DI diesel has the injector at a 90* angle in the center of the piston. The bowl also has a crown inside of it as well. The multifuel is an offset injector just touching the outside of the bowl. That's what promotes the swirl effect of the MAN hypercycle.

Pistons, injectors, heads, IP/or programming, automated fuel metering system, and money.

Ahh... I see what you mean. I was just thinking that if we changed the piston to match the existing chamber, and tailored the piston with the bowl in the correct "target" location we could minimize most changes required to the head side of the chamber.

Nothing says the quench zone has to be nice and flat it we plan the flow right. Or at least that's what I was thinking.

The actual location of the injector/nozzle would be a limiting factor if we can't get the quench-airflow-spray angles right though. I hadn't considered that... I had envisioned any direct injection engine being roughly centered on at least one axis and the new nozzle directable enough to hit our desired target on our custom piston. I didn't take into account all the designs I'm seeing.

It might limit the types of engines that could be successfully retrofitted to MAN type multifuel operation.

 

[Andy1234]

Now I know why my MOM came home fuming mad when they assigned her a new EIT.....

And I'll bet she was even more pissed when the new engineer came up with an idea that saved the company 5-6 figures in production costs....

Andy

 

[4x4 Forever]

And I'll bet she was even more pissed when the new engineer came up with an idea that saved the company 5-6 figures in production costs....

Andy

Actually, the OTHER way around. Most (and I say MOST) EITs have NO clue as to what happens in the real world after school! I also see this in my everyday operations...

 

[Heath_h49008]

I suppose those of us who are EITs with over 10 years experience... mine is automotive as a licensed tech and ASE cert partsman... and background training in welding and machine tool probably don't fit that mold.

 

[JasonS]

Actually, the OTHER way around. Most (and I say MOST) EITs have NO clue as to what happens in the real world after school! I also see this in my everyday operations...

If you need an engineer with experience, hire an engineer with experience (and expect to pay accordingly). It is extremely naive to expect a new hire to be well versed in everything. College teaches the basics of applied science; the details are aquired on the job. If you are not happy with your new hires, learn to hire better people, improve your training, or communicate your needs to your local university/ college.

What is it that you do for a living?

 

[4x4 Forever]

If you need an engineer with experience, hire an engineer with experience (and expect to pay accordingly). It is extremely naive to expect a new hire to be well versed in everything. College teaches the basics of applied science; the details are aquired on the job. If you are not happy with your new hires, learn to hire better people, improve your training, or communicate your needs to your local university/ college.

What is it that you do for a living?

Ships Captain, and yes, I was in the same place as an EIT at one point and time. I would say everyone was at one point! I could have gone either topside or on the bottom.

An experienced Engineer is good to have, but how do they get there? Most likely, just like you said, basics out of college, and then handed over to someone to 'train' them in the real world.

As far as learning to hire better people or communicate with your college/university: We hire who we can get: You interview, background, etc. and make the best choice of who is in the pool. The bad part is training, it is there for free, most of the time you get paid too, and most of them refuse to take you up on it, ie "I know it all already", or upgrade licenses. The ones that 'get it' move up fast, the ones that don't you just have to watch REAL close.

 

[Wildchild467]

I'd like to use today’s technology used to redesign the multifuel camshaft. I know they run good now but maybe there could be more fine tuning that could be done for better valve profiles… maybe even a roller cam somehow. I would think that the advantages of roller camshaft profiles would help the multifuel process. Roller cams are nothing new ofcourse, even when the multifuel was designed. Just a thought. Maybe make sure the engine internals are balanced and stronger rods. But then again the multifuels seem to run good as long as you are not trying to run Indy 500 with it. I dont mean to sound like i am saying the multifuels are bad at all, but it would have been neat to see them evolve a little bit over the 50-ish years in service... or maybe they did with the LDS-427....

 

[patracy]

You could probably have the cam ground and have some rollers built for it, but you're talking the cost of several trucks in just a cam.

If time and money were no object to me, I'd take a LDS. Tear it down and rebuild it. Balance the bottom end. (Crank, rods, pistons) Add a girdle for the bottom end. Have ARP make up a set of custom rod and main bolts. Open up the piston bowls a bit to lower the compression ratio. Have the cam ground but retain the factory lifter/tappet design. Install studs on the rocker assemblies, have custom pushrods made. Install heavier valve springs. Full port and polish on the head assemblies. O-ring the block and heads. Build a custom sheetmetal intake without the coolant system passing into it. Custom header. And probably a S300 turbo in a 62mm compressor wheel. The most expensive parts of that build would be the turbo, intake, exhaust header, cam, and fasteners. The rest is a lot of labor. But I suspect that one could reliably flirt with 300+hp on a routine basis with an engine that could rev near 3K. All while maintaining the multifuel capabilities.

So who wants to donate to the research and development project?

 

[Heath_h49008]

You could probably have the cam ground and have some rollers built for it, but you're talking the cost of several trucks in just a cam.

If time and money were no object to me, I'd take a LDS. Tear it down and rebuild it. Balance the bottom end. (Crank, rods, pistons) Add a girdle for the bottom end. Have ARP make up a set of custom rod and main bolts. Open up the piston bowls a bit to lower the compression ratio. Have the cam ground but retain the factory lifter/tappet design. Install studs on the rocker assemblies, have custom pushrods made. Install heavier valve springs. Full port and polish on the head assemblies. O-ring the block and heads. Build a custom sheetmetal intake without the coolant system passing into it. Custom header. And probably a S300 turbo in a 62mm compressor wheel. The most expensive parts of that build would be the turbo, intake, exhaust header, cam, and fasteners. The rest is a lot of labor. But I suspect that one could reliably flirt with 300+hp on a routine basis with an engine that could rev near 3K. All while maintaining the multifuel capabilities.

So who wants to donate to the research and development project?

After reading about tractor pulling engines built on these bottom ends living happily at 4000 RPM with just a balance job, I'd be tempted.

Let me finish paying off this truck and my overpriced college education first, and I might get on that. Sounds like fun!

One other thought, that may be better on a stationary engine than a truck mounted, would be a dual mode MAN and Diesel system that would allow waste oil AND gaseous fuel operation. Some compressed air ignited fuel MUST be present to provide ignition, of course.

The alternate method would be a set of gas injectors on their own timing circuit, but linked to a common control, that would allow the diesel to lean as the hydrogen/propane/woodgas/methane/Taco Bell flattulence/etc was injected later in the cycle. A near universal fuel engine would be handy for generators/pumps in rough areas hospital/essential services backup.

These Hypercycle engines are not at the end of their life as a design...

Oh BTW... this was where I learned about the design and combustion process for these. It's not a horribly technical read either, although those are out there as well.

PRINCIPLE OF HYPERCYCLE OPERATION

 

[Mike O.]

Convert it to an early VE pump Cummins B5.9, replace the o-rings and seals in the pump (without even removing the pump), throw in some Lucas POD injectors, a 3400 RPM governor spring and a 12cm HX35 and you'll have about 300-350hp all day long...for hundreds of thousands of miles. We did this to a '92 D350 and it ran like a raped ape for 290,000 miles running back and forth from CT to Drummondville, QC through VT @ 22,500 GVW with the trailer.

The seal kit for the pump is $50. The gov spring is maybe $30. Injectors were under $400 on fleabay. HX35 was maybe $600. Quick check of fleabay has Gen1 Dodge engines for about $2,000. Heck, you could run easily get 400hp for another couple of grand!

Mike O.