My experience of using SVO in a XUD9TE Xantia

[XantiaMan]

I thought it was worth writing about my experience using SVO, and its pros and cons!

I started using it last October time when the weather was still fairly mild.

Back then, it was still 54ppl from Asda but i only used small amounts of it and noticed no difference in the way the car started or performed.

As time went on, diesel started getting more expensive Nov/Dec and i was doing alot of miles, so i tried higher amounts of SVO to diesel. Having read the success of people using 5-10% unleaded to cut the SVO to improve cold weather performance, i waited till i started having issues with cold morning lumpyness.

I added just 5% and this almost completely cured the lumpy idle issues from cold, and also when hot!

Happy that everything was ok and the car still performing well with only a slight top end performance loss compared to diesel i piled the miles on.

One day i noticed alot of oil on the back of my car, and a puddle started emerging on the floor overnight. Upon closer inspection it appeared to be leaking from the rear of the pump timing cover, not serious by the time i spotted it, and once i stopped using unleaded and more amounts of diesel to SVO, the leak virtually stopped to be insignificant.

Back then, i was not certain of what caused the pump to spring a leak, and it was easy to point the finger at SVO, however, i am certain that it was a combination of using unleaded which having octane boosters like toulene added that causes seals to swell or shrink depending on age and what they are made of, together with the SVO that IMO, hardens rubber. The icing on the cake was a small amount of acetone that i used as an experiment, again after reading much about it on the veggie forums and generally on the internet.

Had i not used unleaded or SVO, i dont think my pump would be leaking like it has done. It also emerged this weekend that the cause of my lumpy running for the first few seconds overnight was yet another seal leaking, this time from the front of the pump behind the immobiliser guard/injector outlets. This leak was not apparant until i created extra pressure inside the pump by pressing the priming bulb about 30 times! It stopped after the engine had been run for a while, but it seems air is being drawn into the pump overnight.

A problem i can live with for now, at least until the summer has passed!


Now, beyond the basic physical side and the effect it can have on an 11 year old injector pump, there are other downsides.

When run on a high % of SVO, it will smoke at idle, not black, more cloudy blue. Pop some diesel in and the problem goes away. The cause, again IMO, is the higher viscosity of the oil which reduces the fine spray produced by the injectors when a thinner viscosity is used, so what i was seeing was unburnt fuel. Not a good thing at idle, as eventually this could cause ring gumming and worn out cylinder bores.

Again, when on high amounts, you will start to notice the cold start performance is not as good, and in really cold weather the engine will hunt violently unless the car is driven. You may also notice the idle is lumpy when hot too. The smell from the exhaust will be a very rich chip shop aroma which may be sickly to some!

Performance wise, overall you would be hard pushed to see the difference in normal driving. The differences i can tell are a rougher, peakier power delivery, the engine actually feels more urgent on anything over 30-40% SVO, but does start to lose its edge on more than 80% SVO.

MPG is another drawback. I reckon you will see a 5-10% drop in economy, as it does not contain as much energy as diesel. I am easily seeing close to 50mpg on a run on diesel, and not got much better than 45mpg on high SVO mix, with 38-40mpg normal.

Get the mix right and you will see some decent savings in your fuel costs but beware of the potential problems it may cause if you get too greedy!

My engine has had no mods to make it run SVO, only a tweak of the fuelling and boost. It uses virtually no oil between changes and seems to pull better the more miles it has. This is true of an XUD9 running diesel of course, but i see no long term ill effects by having run SVO for over 15,000 miles.

It is a shame my IP has been affected, but i do not regret using SVO and its been good whilst the price of it has been cheap. But with it being close to a £1 a litre and diesel £1.16 a litre around here, there is very little reason to use it and you will make up the difference in the mpg.

One other good thing for me though is a little unusual. Since i got my car it always seemed sluggish to start from hot, taking 3-4 turns to catch although its always been an urgent starter from cold. The cure? Let it sniff some SVO! I've really no idea why it helps but its excellent starting from hot, so thats one reason why i will continue to run up to 40% SVO in my Xantia as long as its 20p a litre cheaper than diesel!

Please note all the above is in my opinion and everyone will have different experiences which would be great to hear about!

Gareth

[CitroJim]

Gareth, excellent That encompasses virtually everything you could ever want to know about using SVO. A very fine post.

It is interesting you speak of hot starting. In my experience, every Bosch pumped car I've had exhibits those symptoms whereas every Lucas pumped car I've had does not. Over the years I've now had just about an equal number of both. Interestingly, Lucas pumped cars also start very urgently from cold

I have pondered this isue many times and discussed in briefly with a diesel specialist. The conclusion is that it is all to do with fuel viscosity changes with temperature and clearances in the pump with heat. Pumps run hot and a hot pump and hot fuel will leak internally within the pump much more than cold fuel in a cold pump. Putting SVO in mainatins a higher viscosity and therefore a hot pump will pump it better than it will hot diesel and therefore improve hot starts.

The Bosch pump uses a different style of HP pump than the Lucas. The Lucas runs closer tolerances in the HP pump and this both may explain why they're better hot starters and certainly explains why they blow up on veg. The very close tolerances in a Lucas pump won't allow cold, thick veg to effectivey lubricate it and it promptly seizes. The Bosch pump runs more generous clearances (as the design does not rely quite so much on very close tolerances) and this is one reason why they survive veg as well as they do.

For my money, and I know some may disagree, the Lucas is a superior pump.

You're bang on the money about cold running on veg. Firstly it does not atomise as well from the injectors and secondly, cold veg does not have the same amount of readily combustible fractions as diesel and rather a lot, those with the lowest vapourisation points, in fact hardly burn and form gums like you see on the edge of a well used chip pan. these can cause trouble by polymerising, leading to gumming of the rings and contamination of the oil. This is less of a problem in an IDI engine but can cuse lots of bother if you try to run a DI engine on veg. Wet veg just sprays directly onto the cylinder walls and runs straight to the rings and sump whereas in an IDI it gets heated and partially burned in the pre-chamber and exits the engine as smelly blue smoke! They make no contribution to the engine running and result in the hunting and rough running.

[MikeT]

A good read Gareth, thanks for sharing.

I'm just about in agreement with all you say, particularly unleaded being a contributor of IP seal failure though I only have one instance of experience. Shortly after using unleaded I had a fuel pump leak - location unknown but suspected at the lower rear plate. I stopped adding unleaded and had no further leaks while the current leak got no worse - this is true during and after 6000 miles of 95% SVO.

Personally, I think acetone is far too powerful and corrosive to risk even when highly diluted but I applaud your experimentation.

I honestly believe all the disadvantages of SVO can be put down to the same single problem - the viscosity. I have read rapeseed oil has the same cetane rating as the best pump diesel so I'm not convinced it has less energy than diesel though I'm not disputing you experienced power and economy losses.

SVO will make the fuel system and engine work harder than it's been designed to tolerate. I suspect injectors are the biggest weak point for all the performance issues you state though the extra work the IP has to do comes purely from the crankshaft which will always be sapping more power than diesel even at idle. JMHO.

[Penguin]

I have read on other forums that people using an XUD have removed the thermostat from the fuel filter to preheat the veg oil lowering its viscosity. I know from previous posts that Xantiaman hasn't done this but I would be interested to hear from other owners regarding this modification. Also on various Veggie burner forums I have read where a number of people have fitted one of the XUD filter housings into their non-XUD car just for its heating effects.

[lexi]

I know people are running all sorts of Veg blends at different percentages etc. It is all reallly a way of trying to avoid the inevitable which is a proper two tank system and an approved heater for the oil.

I run B50 in the Xantia as I do in a Nissan Patrol as well. It is a lot safer and takes the sting out of fuel bills. You also cut the risk of any unfavourable effects should an odd batch of Bio be less than perfect.

Obviously will let everyone know of any issues.....Bosch pump

[Xaccers]

Well, on a trip down to Winchester late one night and in a bit of a hurry, I used up the diesel I had in the tank, and added 20L of soy SVO.
Gave me a 5mph increase on top speed

[Peter.N.]

Very interesting post Gareth. I have heard of many of these charactaristics in other posts, but you have put them all nicely together.

The 2.1 XM uses a fuel heater bolted to the end of the cylinder head, most of which leak and have been disconnected. They are very effective though but I dont know if they would fit the 1.9, they probably would the 2.1 Xantia though.

My experience with pumps is that the Bosch is more reliable and is easier to alter the fuel delivery on but I have never used one with vegie oil.