Fuel additive for efficiency not the bug

Latestarter1 said:
Gone are the days when Cummins PT or Detroit unit injectors would burn just about anything you threw at them and suffer zero ill effects.

When we talk about modern on road as well as future off road diesel engines adulterating diesel fuel could end up a costly mistake. We are not discussing the additives which the fuel supplier blends into the fuel which are formulated at huge cost and understanding of the technologies being dealt with.

As emission levels have tightened it is only electronics and material technology which have enabled diesel engines to stay ahead of the game.

Diesel engines have two primary exhaust components which are on legislators’ hit lists.

#1 Pollutant is oxides of Nitrogen (NOx)
#2 Pollutant are particulates.

We have a dilemma inherent in diesel engine design. If we retard the engine combustion temperature goes down and so does Nox. At the same time particulates go up. Advance the timing and the reverse occurs, so there is a limit as to how much you can clean up “in cylinder”. Get a long party balloon; blow it up, write NOx on one end and particulates on the other. If you squeeze one end what happens to the other, it gets bigger. That is all you need to know to understand low emission diesel combustion technology. Trick is getting the best trade off.

We also have a further problem in that the more we chase the production of particulates in an engine, for example by using higher injection pressures we get less dense but a far finer particulate formation.

The new particulates, below PM10 have a nasty habit of passing straight though the walls of our lungs and into your blood stream.

We have to have some external levers to pull to clean diesel engines up if we cannot do it in cylinder.

Looking at NOx SCR or Selective Catalytic Reduction is the most favoured strategy to clean up truck diesel engines as well as keeping them fuel efficient. Coming back to the party balloon I am going to squeeze the end which says particulates, the end marked NOx balloons out behind me.

I design my motor to advance the heck out of the timing to get particulates down, as for the NOx we let it all hang out!

Now comes the clever bit, could say we are taking the p*ss as we have a small tank of aqueous urea. Under the direction of the vehicle’s ECU/ECM, urea is delivered in precisely metered spray patterns into the exhaust stream just ahead of the SCR converter.
In the SCR converter the conversion happens.

Exhaust gases and an atomized mist of urea enter the converter simultaneously. Together with the catalyst inside the converter, the mixture undergoes a chemical reaction (I can give you the formula, but it would take up most of the page) put simply the reaction produces harmless nitrogen gas and water vapor.

Exhaust gases are monitored via a sensor as they leave the SCR catalyst. Feedback is supplied to the engine computer to alter the urea flow if NOx levels fluctuate beyond acceptable parameters.

Now we take our passenger car diesel engine, put the balloon under our arm and squeeze the NOx end giving us a bundle of particulates to deal with.

This time we are using a DPF which is an acronym for Diesel Particulate Filter. A DPF works in conjunction with an oxidation catalyst and EGR to remove a majority of the NOx, particulate matter and unburned hydrocarbons from the combustion process. As soot is a natural byproduct from the combustion of diesel fuel.

Inside the DPF is a porous honeycomb structure that catches the soot as it passes through. After the soot builds up over time, the onboard computer controls fuel injection to allow unburned fuel to enter the filter at measured intervals where it flares off and generates increased temperatures that incinerate the accumulated soot. The result: Soot is reduce by over 90-percent.

This story is a bit like Alistair Cooke letter from America, where on earth is this leading us?

Screw with a system which uses SCR by adulterating fuel and you are likely to get ammonia slip, the finely balanced chemical reaction results in the production of ammonia from the exhaust, not nitrogen and water. The vehicle system is set to monitor this condition, result engine shuts down to idle.

Trip to franchised dealer for tanks to be flushed and ECM/ECU reset, all at some considerable expense.

I am worried you say, I just have a DPF on my car. Well that sneaky snake oil you put in the tank can tend to coat the oxidation catalyst, so more junk goes down stream into the DPF which tries to regenerate, vehicle is constantly sensing the Delta P across the DPF, engine ECM/ECU is trying to get the DPF to regenerate by injecting fuel very late, in fact too late for generating engine power, just wants to reduce Delta P inside by incineration.

Warning light comes on in vehicle, trip to the dealer. Unless dealer can use his service tool to force regeneration you are saddled with the cost of a new oxycat and DPF.
All manufacturers are testing these technologies on future marine engines, it is here, now today.

Now you know why I believe in clean fuel free of third party junk.
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I may be a bit stupid but I think are you just taking a long time to say that we shouldnt use additives particularly for reducing emmisions.
I dont really understand your point.
I prefer the logic in the weblink above.
Make the fuel burn better and you get a cleaner exhaust and better effeciency.
 
Hurricane said:
I think are you just taking a long time to say that we shouldnt use additives particularly for reducing emmisions.
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Well, I for one had a very different understanding of LS1 (indeed interesting) post.
What he's saying is that modern, emissions oriented engines can simply "refuse" to work with these additives, if I got it right.
Otoh, a question for LS1 which pops to my mind is, what about using the additives which are being discussed in not so modern, not electronically controlled engines with no DPF or SCR?
I guess that the simpler logic of achieving a higher efficiency through better combustion (regardless of what happens to NOx or particulates) should work in this cases. And if not, why?
 
Latestarter1 you beat me to it.

I was just about to write such a response and show the forum the extent on my knowledge on the subject. (I WISH)

Excellent and very clear description in laymans terms.

Thanks for taking the time and trouble it has helped me to understand the subject more fully.
 
MapisM said:
Well, I for one had a very different understanding of LS1 (indeed interesting) post.
What he's saying is that modern, emissions oriented engines can simply "refuse" to work with these additives, if I got it right.
Otoh, a question for LS1 which pops to my mind is, what about using the additives which are being discussed in not so modern, not electronically controlled engines with no DPF or SCR?
I guess that the simpler logic of achieving a higher efficiency through better combustion (regardless of what happens to NOx or particulates) should work in this cases. And if not, why?
Click to expand...


Good question MapisM, I am keen to hear the answer.
 
Latestarter
From your posts you would seem an expert in the field of diesel fuels and filters, were as the majority of us just have an opinion on these subjects.
To save unqualified attacks on your words, it might be appropriate to give this forum your background in diesel fuels. If you are an expert your views would be greatly appreciated by us all.
On the subject of additives, I was recommended diesel treatment from volspec. Would this be a benefit to my Volvo D4 engine or a disadvantage?.
David
 
As a bloke who used to be fairly well up there with diesel engines (well over 250 units of various makes and models overhauled at a large diesel engine reconditioners), I am happy to confirm that Mr Latestarter really does know his stuff, far more than I do actually.

He's no BS merchant. :)

Only thing we differ on with this post is I'm happy to put Redex Diesel Treatement in me car and got an improvement and he is not.
I merely give a nod to the "suitable for HPCR and Catalytic Converters" printed on the side of the bottle.

I would not put

Dr Snoobs Snake Oil Diesel Treatment - 1000mpg Guaranteed, Engine never wear out.

Dr Snoob PO Box 145
Nigeria.


In my car or any other diesel engine. :)
 
OK so here are the results of my little test.

First - without the additive
190.0 miles used 35.06 litres

Then with the additive
188.8 miles used 32.78 litres

In both cases about 95% of the journey was done at a constant 70mph using a cruise control.
There were only a couple of very short contra flows where the speed dropped to 50mph and no traffic jams. In fact we had one of the best journeys up and back that we've ever had.

So, using the above figures, our Landcruiser did 5.419 miles per litre without the additive and 5.757 miles per litre after the additive.

So about a 6 or 7 per cent saving.

I'm not going to draw a conclusion but, personally, I was expecting it to be roughly the same with the additive - the amount that I put in was really very small - about a quarter of the little 25cl bottle for 80 litres of fuel. The instructions on the bottle indicated that 25cl was the amount required for 400 litres of fuel.

As I've said above this cannot be a proper test but it was something I could do quickly before I poo poo'd the whole idea.

In fact, I think this little test shows that it isn’t worth poo poo'ing and that more information is required. I'm only a layman in this matter but I suspect that it takes a while for the fuel with its new additive to burn correctly and longer term usage might produce better results. I still can’t see how such a small amount of additive (allegedly) makes this kind of difference. But if it really does make a saving of even 5%, I would certainly want to know more. JW takes 4000 litres of fuel and I can use over 3000 litres a day sometimes so 5% saving would definitely be worth considering.
 
Hurricane, I've always been a believer of diesel fuel additives too. I think that their is a cleaning agent that helps to keep the injectors working more efficiently. Therefore giving a better performance. Hope the pros will shed more light on the subject.
David
 
jfm said:
Shell pay the fuel tax, not the customer. Sure, they pass it on to the customer, but like VAT it is embedded in the price.

Let's say a litre of fuel retails £1 and the fuel tax is 60p/litre. Ignoring VAT (which doesn't alter the analysis), the customer gives £1 to Shell who give 60p to exchequer and keep 40p as Shell's revenues.

Now let's say Shell make this new fuel that has 10% more calorific value and they sell it at £1.10 a litre. As a customer you are indifferent becuase you pay 10% more per litre but you buy 10% fewer litres for the same mileage, AOTBE. As a customer you therefore only buy 0.9 litres to drive the same miles as the 1 litre of old fuel would have taken you. Shell still get £1 of gross revenue, but now they only have to give 54p to government as tax, so they get to keep 46p of revenues, not 40p

In other words, in a theoretical world and AOTBE, if Shell can pack more joules of energy into a litre of fuel, in a tax system where fuel duty is charged on volume not energy content, then their revenues rise (in the above example by 15%, being the 10% x the ratio between the 60p and the 40p ie 1.5x).
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hmmm.. seems to me that they have put the price up 10ppl from £1.00 to £1.10, so they make more profit. The tax is still 60pct.Lets say they didnt change the price. You now buy .9 of a litre at 90p, 54p goes in tax, 36p goes to Shell, so now they are worse off as total volume sold drops. I dont see its the tax- they need to put the price up to match the loss in volumes. If they put the price up more than that , they make more money, but that just the same as raising the price full stop.
So I dont see the tax system means they make more money on a more efficient fuel, unless they overcharge for it !
 
Hurricane said:
I think that was jfm's point - they do charge extra for the "Ultimate" (special) fuels.
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OK, I might be misunderstanding JFM's focus on the tax being non calorific count related. I can see that helps Shell disguise an inceased margin on the premium fuel, but it is the price hike itself that makes them more money, just as a price hike would do on standard fuel. So, yes, IF tax was calorific count related, that would mean they couldnt hide the price increase on the fuel per mile.
 
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