Nov 9 2007, 10:08 AM
Citreon ZX 1.9 TD (with a Bosch injector pump)
Currently running approximately 30% vegetable oil. Chugs a little on cold startup for about 5 seconds, and then drives and idles perfectly as before. Seems noticeably quieter at idle as well once warmed up, and driving at night, there's now no smoke at all visable in the headlights of cars behind under full boost/load. At idle atleast, the tale-tale "chippy" smell is barely noticeable.
With diesel at 102.9p/litre and vegetable oil at 56p/litre, running a 30% veg oil mix reduces the cost of a 50 litre tank from £51.45 down to £44.42 - a saving of £7.03 a tank, or approximately £400 a year.
Nov 12 2007, 11:57 AM
Continued the experiment over the weekend, and increased the veg oil concentration upto about 50% or so.
It's now noticeably lumpier for 5-10 seconds when started in the morning and the neighbours don't look too impressed at the cloud of grey smoke that comes out the back as it sits there chugging away, but it still starts first turn of the key and after a few seconds it settles down to a nice smooth idea (well, as smooth as diesels ever are) with no smoke. Seems to drive fine even with the engine still cold, and the only give away is the smell - you can now clearly smell it at idle and when crawling along in traffic, and the words from a friend who followed me at the weekend (and didn't know anything about the veg oil) was "your car stinks"
Nov 20 2007, 10:41 AM
1500 miles of running on veg oil and diesel mix now, and all is well still
Economy seems to be about 5% worse running on veg oil mix from what I can tell, although the fuel savings more than offset that given the price of diesel is continuing to rise. Currently running a 40% mix which still starts easily in the morning, although it chuggs and smokes noticeably more when it's below freezing outside and takes a few seconds longer than normal to settle down to a smooth idle - I have a suspicion that atleast one of the glow plugs has failed which really won't be helping matters mind you. Once it's settled though, it behaves and drives just like on straight diesel, but with the added aroma of chips...
Quick calculation suggests that over the 1500 miles or so that I've been using veg, it would have cost me about £160 if I was running straight diesel, whereas running a 40% veg oil mix saved me about £33 or so - a 20% saving, give or take. OK, so it's not going to make me my first million anytime soon, but another £50 minimum in my pocket every month for minimal time/hassle isn't to be sniffed at
Dec 13 2007, 03:02 PM
Since my last update, I've been increasing the percentage of vegetable oil in each tank until I've got to the point I'm at now where the car is happily running on straight vegetable oil with no diesel or anything else added to dilute it
The engine still starts first turn of the key when the glow plug heating light has gone out even when it's below freezing outside, but it's very lumpy for the first 20-30 seconds or so and chucks out quite a lot of smoke and then "hunts" with the revs rapidly rising and falling by a couple of hundred rpm like you're lightly blipping the throttle. Once the engine begins to warm up though it's fine and on the move you don't notice the difference over running on diesel.
Only issue I've noticed since running on straight veg oil besides the rough cold starting is that when warmed up the idle seems slightly lumpy, like it's not quite firing perfectly on all four cylinders - it's very subtle, but you can feel it missing slightly through the vibrations entering the cabin. However, given that the head gasket failed shortly before running it on straight veg oil, I'm not sure whether this lumpiness (and indeed some of the cold start roughness/hunting) is a side-effect of the veg oil, or whether one of the cylinders is down on compression thanks to the HG fault and thus isn't firing properly.
The price that I'm able to easily obtain vegetable oil has risen sharply from 54p to 70p a litre - I assume as a result of so many people now running their cars on it - but moving to straight veg oil (rather than the 40% mix I was running previously) means that I'm saving a significant amount of money over regular diesel (currently 106p/litre locally, and over 1.10p on motorways).
I'll update this thread again in a month or so to let you know how the Bosch pump fairs in terms of reliability running on straight veg oil, and whether the replacement engine (without the failed HG of the existing one) improves the cold start and warm idle lumpiness
