Calorific value of diesel????

[The Lovely Boyo]

Hello,

Does anyone know the calorific value of diesel versus that of vegetable oil?

The reason I ask is that I am curently running on 20% veggie. Whilst this allows me to fill up for £10 less per tankful, my fuel economy is definitely worse. Detailed figures to follow.

If veggie oil has a lower energy content then I would need to use more to do the same work (milage in this case). Is this what I am seeing as worse fuel economy?

Discuss (PhD students please keep it simple for us) Thanks

[TonyN]

http://www.indiasolar.com/cal-value.htm

This is interesting, but it doesn't list veg oil.

[pops]

Veg oil is more fattning diesel just makes you sick

[Apache]

Hello,

Does anyone know the calorific value of diesel versus that of vegetable oil?

The reason I ask is that I am curently running on 20% veggie. Whilst this allows me to fill up for £10 less per tankful, my fuel economy is definitely worse. Detailed figures to follow.

If veggie oil has a lower energy content then I would need to use more to do the same work (milage in this case). Is this what I am seeing as worse fuel economy?

Discuss (PhD students please keep it simple for us) Thanks

Definitely a real effect. I find I get around 50 miles less to a tankful when using Bio. I reckon it works out about cost equal to standard diesel overall.

[Bobby Doc]

I will answer this briefly....

2/3=xy+z-y2"/47%+a,2(x+z=Y)
(-47)+Co2=4

O.K.

[Matt the Cat]

I will answer this briefly....

2/3=xy+z-y2"/47%+a,2(x+z=Y)
(-47)+Co2=4

O.K.

I always thought it was 49% in the middle of that equation, but i suppose it depends on wether it's followed by +a or +c. Still equals 4 though, so it doesn't really matter

[DaveD]

Veg oil is more fattning diesel just makes you sick

[dirtydog]

Definitely a real effect. I find I get around 50 miles less to a tankful when using Bio. I reckon it works out about cost equal to standard diesel overall.

I defo get less miles on Veg.

[joe112]

I don't find much difference in milage/tankful on veg - I am running upto 50% at the moment with no probs... the only real noticible difference (apart from the smell) is a lack of power... the engine doesn't have as much 'guts' as it does on diesel

its currently costing me about £40 to fill up on diesel and veg.. about a £15-£20 saving... well worht loosing a bit of power for

[BUSHWHACKER]

You'll probably find that power will be restored when the warmer weather comes, or if you fit a fuel heater.

[dirtydog]

ive got one
is a tiny bit slower on veg

[Morr]

The calorific value of Vegetable oils is around 37,000 kJ/kg, whilst Diesel is around 42,000kJ/kg.

This means that Diesel has around 10% higher calorific content per kg, however the rate and measurement of your engines consumption is by volume not weight.

The density of veg-oils is up to 10% higher than Diesel, so the weight of oil consumed is higher than diesel for the same volume, this means the the calorific content available from veg-oil is higher when measured volumetrically, and should be nearly equal to that of Diesel.

A very small loss of energy by volume can be expected, however this is only slight, and should be in the order of 5% at most.

This can therefore translate into a potential drop in economy of up to 5%. This is however assuming a switch to 100% veg-oil. Use of a 50% mix would therefore yield an increase in consumption of up to 2.5%. On a vehicle returning 25mpg, this works out at 0.625mpg worse off, this should hardly be noticeable, and far outweighed by the environmental and monetary savings.
Personally, when I first starting using veg-oil I was keeping records of my fuel consumption and could detect no difference whatsoever.

[The Lovely Boyo]

Hello,

I've had a look at the interweb and it confirms most of the technical points (95% energy content by volume etc, etc).

Still leaves me with less per tank - looks to be about 10% at first glance.

Curiouser and curiouser.............

regards

[Morr]

Other factors can also come into play, comparing energy content is really only relevant if both fuels are to be burned under ideal conditions. Considering the modern compression ignition engine has been tuned to burn fossil fuels, it will therefore offer an injection/combustion process that can prove better suited to diesel when compared to veg oil. This is why certain engine types readily take to veg oil, whilst other may require modification before successful use, and some some not use it at all.

A number of elements are crucial to successful use of veg oil including the fuel pump, the injectors, combustion chamber design and overall condition of the engine. On Surf's the fuel pump is fine and the combustion chamber is not something you're likely to try and modify, of the remainder the injectors are the most influential item. If these are in poor condition, worn, clogged, etc. then whilst not at optimal on the diesel they're designed for, they could potentially be even worse on alternate fuels such as veggie. They may be spraying inefficiently, a problem which would be exacerbated by the higher viscosity of the veg oil.

Injectors in poor condition would certainly be a prime suspect if a vehicle is getting noticable worse mileage on veg-oil.

[joe112]

as mentioned in previous posts... I've got no probs with MPG on Veg... More lack of power, not to the point where I would stop using it, but could this also be down to injectors.. I've had the turck just over a year and ive never touched the injectors otyher than for bleedin'... how often/shoud you service/replace injectors???

Basically I have no idea if they've ever been changed at all


EDIT: Morr - Those posts above may well be worth adding to the sticky veg thread?