Common Rail and Biodiesel

TDiMike

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What the concensus here - is 1600 bar injection pressure engine (new VW common rail) ready for extended, multiseason biodiesel use w/o additional problems?

I mean, the current crop of diesel engineers are set on making diesel spray as fine as possible, and under high pressure. What's a change in fuel viscosity going to do to an injection system like this after extended use? I'm talking about bio that meets ASTM-spec yet still varies from the viscosity of dino diesel or ULSD.

Now, the ALH engine and it's lower injection pressures is more than tolerant of extended B100 use, as everyone here knows. Finally we're seeing biodiesel availability and pricing "hitting its stride" in North America. Are we now going to get the rug pulled out from under us by Common Rail sensitivity to anything >B5 ?!

Input from the JeepCRD, Sprinter, E320 CDI, or heavy duty domestic truck crowd or weblinks to their discussion would certainly be relevant here.
 
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DPM

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PSA will only warrant B5 in their common-rail engines. I've run mine up to B80 (highest available locally) quite satisfactorily. Quieter, smoother, a few mpg worse. No injection-system side-effects that I can attribute.
 

RC

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The $64,000 question TDiMike.

If there is a will by the manufacturer and OEM supplier to design/build equipment to handle various viscosity biofuels it can be done. Will there be the demand/attention? Time, and a good deal of work, will tell.
 

BioThomas

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RC said:
The $64,000 question TDiMike.

If there is a will by the manufacturer and OEM supplier to design/build equipment to handle various viscosity biofuels it can be done. Will there be the demand/attention? Time, and a good deal of work, will tell.
There appears to be a continuous drive towards biofuels, as in biodiesel and ethanol, especially in Europe. I believe that the engineers will be forced to take this into consideration. After all, if they don't sell any cars, they'll be out of a job.
 

naturist

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TDIMike, the jury is still out on possible bad effects of the higher viscosity biodiesel vs petroleum diesel on common-rail injection systems.

I know of people running Liberty CRDs on B100 exclusively. So far, with a tiny sample of a half-dozen units, averaging around 13,000 miles each, no problems BUT this is too small a sample of vehicles to be statistically significant AND says nothing about long-tern effects, such as erroded injector orfices.
 

TDiMike

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naturist said:
TDIMike, the jury is still out on possible bad effects of the higher viscosity biodiesel vs petroleum diesel on common-rail injection systems.

I know of people running Liberty CRDs on B100 exclusively. So far, with a tiny sample of a half-dozen units, averaging around 13,000 miles each, no problems BUT this is too small a sample of vehicles to be statistically significant AND says nothing about long-tern effects, such as erroded injector orfices.
Your CRD reports is very interesting, and I hope you'll continue to update the masses on this group's success with B100. Long term and performance of B100 or B20 in near-freezing climates would also be valuable to pass along.
 

McBrew

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My Sprinter seems to run fine on B100... but more than half of it's 56,000 miles were petro-diesel. That ratio is going up in favor of bio now that I have remped up production in my garage!

Like RC said, time will tell.
 

bioTDInBENZ

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Mercedes did tests in india on 2 C320 CDI's and a CDI van. Ran them on japthora B100 for 100,000 miles trouble free. The link on the article seems to be broken on daimler-chrylers site. But they may have updated it.

But if i remember correctly they drove the cars in freezing temps with B100 in the tank and the cars were all fine. They had the "biodiesel option" installed but from my understanding all that is, is sensor that calculates how much biodiesel is in the tank and change the fuel pressure to lower the nox increase.
 

Audi5000TDI

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bioTDInBENZ said:
Mercedes did tests in india on 2 C320 CDI's and a CDI van. Ran them on japthora B100 for 100,000 miles trouble free. The link on the article seems to be broken on daimler-chrylers site. But they may have updated it.

But if i remember correctly they drove the cars in freezing temps with B100 in the tank and the cars were all fine. They had the "biodiesel option" installed but from my understanding all that is, is sensor that calculates how much biodiesel is in the tank and change the fuel pressure to lower the nox increase.
Please elaborate on how changing the fuel pressure lowers the NOx emmisions and how the pressure lowering in acomplished.. A link would be useful to promote this wonderful feature.
 

bioTDInBENZ

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Audi5000TDI said:
Please elaborate on how changing the fuel pressure lowers the NOx emmisions and how the pressure lowering in acomplished.. A link would be useful to promote this wonderful feature.
yeah the link seems to be broken, it explained the "biodiesel option" just do a search of "common rail biodiesel" and the old topic should come up with the link but again its a broken link. Got the link off the mercedesshop forum, they explained the option as well, i can go searching for that as well.
 

DPM

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Injection pressure, and thus quality of atomisation is freely selectable on a common-rail vehicle. Rail pressure is set using a closed-loop feedback circuit, from a map in the ECU.
Now I'm no emissions expert so I'm going out on a limb here; but cooled EGR reduces NOx by promoting poorer and cooler combustion, right? I'd guess a lower rail pressure and therefore larger droplets might just do the same thing...
 

naturist

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DPM, you may be right about the larger droplets being the reason lower pressures might reduce NOx.

But the reason cooled EGR gasses lower NOx isn't poorer combustion, but that the increased mass of inert gas (ie, not oxygen) lowers combustion temperatures (more mass to heat up) and the reduction in the oxygen concentration shifts the O2 + N2 <-> NOx equilibrium reaction to the left, away from NOx.

One of the beauties of using piezo-electric injectors is that you can put in multiple small injection events each power stroke, spreading out the burn, thereby lowering peak temperatures (when the NOx is formed) and reducing the need for an EGR system.
 

McBrew

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I might be taking back my "Sprinter runs fine on B100" claim. It suddenly lost a lot of power the other day, and hasn't gotten it back. All signs point to the low pressure fuel pump (lift pump). That sucker is about $400. I'll keep everyone posted.
 

RC

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Looking forward to any updates Jesse. Hope it doesn`t turn out to be too bad for you... or us all. Thanks for your commitment.
 

Drivbiwire

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VW's Common rail motor will have injection pressures of 2500bar, thats 37,000 psi folks.

This will be done by using a standard common rail high pressure pump (24,000 psi) then have pressure stepping within the injectors to bump it another 13,000 psi at the nozzle.

The other aspect is we will be looking at 5 injections per combustion stroke verses the current 2. However the biggest difference is the injection events are electroniclly controlled rather than a simple hydraulic system as in the TDI. The multiple injections are and can be shut off during certain operating conditions where noise is not a factor (hard acceleration).

It can be done, but I suspect that specific changes will have to be made to the fuel systems. If I recall the CDI with the Biodiesel modification has different injectors than the D#2 models.

DB
 

MethylEster

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Please refer to the attached article which has the viscosities of various methyl esters at various temperatures. I'm referring to table 2 which shows the soybean based methyl ester viscosity is actually lower than the dino based diesel at all three temperatures.

http://www.chanco.unima.mw/physics/biodieselanaly.html


The only concern I have is how much glycerine is left in the biodiesel as this can detrimentally affect the viscosity of the final fuel.

Does anyone have any published data to refute the above article ???
 

leicaman

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Will this mean greater efficiency perhaps? Will TDI fuel economy go up as a result of the new system? We already know it will be more complex as far as electronics are concerned.
 

BleachedBora

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VW+More complex = I think I'm keeping my A3 for a while ;)
 

McBrew

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All signs point to the low pressure fuel pump (lift pump). That sucker is about $400. I'll keep everyone posted.
For those who are interested... I removed the lift pump (cam driven) last night, and it is actually a gear pump. It looks really good inside... no signs of wear, damage, or leakage. Just a few turns of the shaft by hand causes enough suction to hold my finger. I don't think that is the problem.

I really hope it is not the high-pressure rail pump going south. I doubt it, since the problem was instant-on. There was no slow loss of power. It was like flipping a switch. I hope it is a simple (cheap) sensor, or something like that.
 

DPM

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Tee into the supply rail after that pump, and see whet pressure you're getting. It might also be worth pulling the pressure control valve (solenoid valve) off the end of the rail and getting it cleaned in an ultrasonic bath.

It would set a code if unable to meet requested rail pressure tho.

Do you have the manuals? If not, empty your inbox... :)
 

McBrew

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DPM, I do not have a Bentley manual or equivalent for the Sprinter. There was not a CEL until I unplugged the MAF. My cheapo code reader tells me that the CEL is on, but that there are no codes. It won't clear it, either. My friend with a MB diagnostic computer says that they will not communicate with Sprinters. I guess they only work with Frieghtliner/Dodge systems.

Is the pressure control valve at the rear of the rail? There is oil all over the front of the intake manifold and surrounding area because the [whatever] actuator on the front of the manifold leaks some oil. Not enough to have to top up in 15,000 miles, but enough to make a bit of a mess. I checked a few connections and they look clean inside. What is that big actuator? Could it be at fault?

I really appreciate any help you could give me... there aren't too many people on this side of the 'pond' that know how Sprinters work.
 

McBrew

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DPM, thanks for the manuals, they will certainly come in handy.

UPDATE: My Sprinter had a failed EGR valve, which put it into limp mode. Covered under the 100k mile emissions system warranty. The problem was NOT biodiesel related.
 

smartzuuk

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My smart fortwo diesel, which is a CDI, runs fine on B20. I noted a little bit of sluggishness on B80 and B90 - but that could be due to the energy content...

I've run B20 and other blends during the last 25,000 kms, not 100% of the time, but enough to have a reasonably good feeling about it.
 
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