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Some of the latest diesels are tweeky on Bio but should run ok on 50-50. Older cars with Bosch injectors will run on nearly anything including straight veg oil mixed with a bit of diesel.
The 5% warranty limit is just a motor industry ruse to stop people using biofuels!
Dunno who the 'expert' is who says that biodiesel lacks lubricity, it actually adds lubricity, extends engine life and reduces 'diesel knock'. As for 'gumming rings' I've had several heads off of cars running on bio and so far have never seen this!
Beware of experts and garages who have never had any first hand experience with biofuels and will pin any fault on the fuel you are using! So easy to charge £800 for a new pump rather than £20 for a simple filter change!
I'm very critical of the latest diesel cars, they are not as robust as the older type and we will not get the 250,000 plus miles out of these engines regardless of what fuel is used!
Biodiesels are not for everyone but the reply regarding older cars is dead right. Run an old banger on bio for a couple of years, if the car wears out anyway regardless of fuel used then sling it away a get another! Its just about the cheapest form of motoring!
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The 5% warranty limit is just a motor industry ruse to stop people using biofuels!
I thought it was a big oil company conspiracy! Seriously, why would the motor industry have a vested interest in how a driver fuels his car? As I said before, you can modify an engine to run on just about anything-if it's worth it.
As for 'gumming rings' I've had several heads off of cars running on bio and so far have never seen this!
The engines you dealt with weren't IDIs were they? With a prechamber, the fuel shouldn't get to the rings. IDI allow a very crude injection system to be used with large single hole nozzles, 300 bar maximum pressure. Common rails idle on 300 bar. Yes, they were tough, but the output is very low (about 30hp/litre)-as is the level of refinement.
Modern diesels frequently run at 75+hp/litre. Some people think this is a good starting point for turning the wick up. I don't. If maintained properly, these new fangled common rail engines can turn in big mileages.
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as the older type and we will not get the 250,000 plus miles out of these engines
regardless of what fuel is used!
You must live in a different world as I ewgularly see {SA HDI engines advertised with over 200k miles.
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madf-you can get 200,000 miles out of an HDI-but only if you use chip oil to 'lubricate' them. ;)
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Is there an explanation to this?
Why should bio diesel be off limits for a CR engine? The stuff about lubricity does not stand up, cleanliness is easily addressed with a filter pack and still we get the seemingly, unfounded horror when some one asks the question.
The lacquer on pans is a red herring too, that is due to heating the oil, not it's combustion.
Any science to it, leaving the anecdotal, apocryphal and emotional to one side?
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Just thought I'd bump my question up a little. It has slipped down the forum, is this because no one has an answer?
Strange given the reaction using bio in CRs usually provokes.
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madf-you can get 200,000 miles out of an HDI-but only if you use chip oil to 'lubricate' them. ;)
Rofl.
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Given Renault's seeming inability proven over the last decade to control the quality of their cars and engines, putting home made fuel into a Renault diesel is well................ perverse. (putting it as politely as I can)
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Had a colleague who commuted from Hampshire to Derbyshire weekly for two years running his Laguna 1.9 on a 50/50 mix of veg oil and diesel with no problems.
They seem quite popular in France.
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You do seem determined to provoke a squabble-and I'm always game!
First-that 1.9 laguna wasn't an IDI 1.9, was it? We've established that you can run pretty much anything through an IDI engine.
Secondly, people HAVE reported running veg oil successfully through CR engines. But they usually fit a second tank. The journey is started and completed on petrodiesel, with a switch to veg oil in between. But this is far too much hassle for most people. Like hypermiling, this is more of an intellectual exercise, than a cost saving measure.
The snag with gambling with CR is that the fuel system components are very expensive. This leads to a paradox. If you can't afford a tank of forecourt diesel, you can't afford to risk damaging your CR fuel system. If you can afford the risk of junking the CR system, the savings just aren't worth the bother.
When it comes to fuel economy, it's usually worth looking to trucks. They've been using high pressure DI turbo diesels long before they became trendy in passenger cars. A typical 44 tonne truck does about 8mpg and covers over 70,000 miles p.a. The fuel cost is huge. Do they run them on vegetable oil? No, because if they did, then used chip fat would become a valuable commodity. in fact the price would rise until it was only marginally cheaper than forecourt diesel. Car drivers wouldn't get a look in because the truck firms would win on economies of scale.
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I quoted the Laguna story to partially refute the Renault "myth".
I wanted an explanation, not that we don't do it because they don't do it or we don't do it because this might happen.
I also wanted people who recoil in shock at the thought of running a CR on bio, to sit and think what they do actually know, and are not just joining in a mass hysteria.
I can afford forecourt prices, but I prefer wholesale veg oil prices, both for driving and cooking.
Edited by davmal on 08/02/2011 at 15:40
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I also wanted people who recoil in shock at the thought of running a CR on bio, to sit and think what they do actually know,
The converse also applies. Veg oil fanboys should think about what they don't know. I've seen a lot of mangled descriptions of combustion in diesel engines-public understanding of fuels is generally poor. Bio fans will point out that biofuel tend to have a higher cetane rating than diesel, therefore it burns 'more cleanly'. No. It ignites more easily. Bio fuels tend to have a higher molecular weight than petrodiesel. Molecular weight and cetane rating tend to rise together. Unfortunately, heavy weight fuels tend to burn less cleanly than lightweight ones. The fuel initially undergoes pyrolysis and there are many stages of oxidation before the final species of carbon dioxide and water are produced. The intermediate stages of oxidation are a problem. You need high temperatures and long residence times to get complete combustion. Typical automotive diesels have neither. They operate at comparitively high speed and low load. This means that 'deposits' are almost inevitable.
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Interesting debate this,going back to diesel when Rudolph Diesel inventend the diesel engine his first fuel used was peanut oil.
I believe in Germany they are working on diesel engines which can run on a far higher percentage of bio fuel.
Here in yorkshire a bio fuel plant will be running this year with a high output,the local farmers are happy anyway.
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Ahh, but that wasn't a common rail, was it ;)
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No it wasn't. There's a lot of pratting about and claims of 'breakthroughs' about converting engines to run on recyled peanut butter or what have you. It's not a technical problem (for OEMs). The problem is one of scale. There simply isn't enough bio fuel production capability for the OEMs to waste time converting the fuel system on mass produced cars. The world's arable land use is groaning under the stress of providing food for 6.5 billion people. Most of the rest of the land isn't fit for growing anything at all. I for one would rather not see virgin rainforest being destroyed to plant palm oil to produce biodiesel so that ignoramuses can dodge taxes and pretend to be green.
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The crops are growing here in yorkshire by local farmers like i said they are happy.
If we are talking about feeding over 6 billion people we are talking about genetic modifeid food for the future but thats another can of worms.:)
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Nothing common about a diesel davmal :)
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What's wrong with GM crops? I bet the farmers are happy-they have every incentive to increase the demand for land use-they have a vested interest. But it would make much more sense for British farmers to grow food for the British market. Nothing xenophobic here, it just can't make sense to import lamb from new Zealand!
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Nothing wrong with GM crops as far I am concerned if it stops people starving I am all for it.I dont know about cheap butter and lamb from New Zeeland thats all in the past.
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I quite agree with most of your points on sustainability, though production of diesel now involves extracting oil from sand and shale, which is not a pretty process and greatly affects flora, fauna and , most worryingly, the water table. However, my first point still stands, that many readers throw up hands, gnash teeth and rant - with anger of biblical proportion - about the terror of using bio in CR engines, with almost as much fervour as when someone puts petrol in a diesel, yet you cited that there are instances where a CR can. Bull about lubricity is the usual tale of woe.
Let's get some science and technology involved, someone explain to me why it's so bad? And explain doesn't mean "because it happened to my mate"
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Right . Here's a simple answer. Modern diesel fuel has additives for cleanliness etc..
Period.
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Go on then, what are they and what do they do? What is the "etc". Why can't they be added to bio? Would Miller's do the same job?
Where is the science, technology and subject knowledge in that answer?
An African Grey could be taught that kind of response!
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I thought I did explain my concerns regarding its molecular weight . The high molecular weight of most forms of bio really is the key to the problem. When cold, the high viscosity puts strain on HP fuel pumps. There is no effective additive that can reduce the pour point of 100% bio. The high molecular weight also makes clean combustion in a high speed diesel engine difficult (read not possible in all driving conditions).
There are other problems. Unlike petrodiesel, biodiesel tends to contain oxygen and has poor oxidation resistance. This is important since most of the fuel that passes through the fuel system is returned to the fuel tank. Whilst in the fuel system, it becomes heated and will start to oxidise, increasing acidity, viscosity and a tendency to form a 'gum' which clogs lines and filters. The high acidity has a tendency to attack seals. Water content: with 'home brew' it is difficult to get the water content to acceptably low levels. The presence of water will allow microbial growth which will form sediment and clog filters. With the exception of high viscosity cold weather issues, most of these problems are insidious, meaning the driver is blissfully unaware of the havoc being wreaked' inside his sophisticated modern engine.
Is that enough? No anecdotes of Uncle's Tom's 335D exploding at the sight of a bio diesel sign. Just chemistry.
in engineering, the salient question is not: CAN it be done?', but 'is it worthwhile to do?' With modern passenger car diesels, the answer is usually a resounding .'NO'.
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