Club 80-90 Forums

CO = 0.1%, HC = 50
You do know you're supposed to test with the engine running?

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ajsimmo wrote:CO = 0.1%, HC = 50
You do know you're supposed to test with the engine running?

I’m not making those numbers up...

I was putting the results down to the quality of my rebuilding but you are bursting my bubble.

Maybe the MOT kid didn’t know he had to put the pipe on the exhaust?

Tested today. Similar HC reading. 2.1 DJ auto. Has a tendancy to cut out now and then. But a good runner. About 19mpg

You can only estimate by calculating the theoretical amount
http://ecoscore.be/en/info/ecoscore/co2" onclick="window.open(this.href);return false;

Good link, thanks.
I like the bit that shows one way that LPG is better for the environment:
Diesel = 132g CO2/km
Petrol = 120g CO2/km
LPG = 83g CO2/km

That's a massive difference, even allowing for slightly reduced mpg on LPG.

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ajsimmo wrote:Good link, thanks.
I like the bit that shows one way that LPG is better for the environment:
Diesel = 132g CO2/km
Petrol = 120g CO2/km
LPG = 83g CO2/km

That's a massive difference, even allowing for slightly reduced mpg on LPG.

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And yet my mates Citroen C3 diesel 1400 car tax is £30 annum. against my last LPG Camper RFL tax of £270. Do we feel an injustice?

ajsimmo wrote:Good link, thanks.
I like the bit that shows one way that LPG is better for the environment:
Diesel = 132g CO2/km
Petrol = 120g CO2/km
LPG = 83g CO2/km

That's a massive difference, even allowing for slightly reduced mpg on LPG.

Slightly unfair though because the energy content of the fuels is different, so using the same volume of fuel per distance is not comparing apples with apples

Good find though - he must have had a good mole to find that.

My euro6 is £140 pa (standard rate).
To get £30 ved it must have been registered 2001 - 2017 and is in band C.
All the differing rates are a minefield.

937carrera wrote:

ajsimmo wrote:Good link, thanks.
I like the bit that shows one way that LPG is better for the environment:
Diesel = 132g CO2/km
Petrol = 120g CO2/km
LPG = 83g CO2/km

That's a massive difference, even allowing for slightly reduced mpg on LPG.

Slightly unfair though because the energy content of the fuels is different, so using the same volume of fuel per distance is not comparing apples with apples

Good find though - he must have had a good mole to find that.

I realise including diesel is not a direct comparator, but with all the other nasties in diesel emissions I think we can write that off as the worst overall.
Petrol v LPG is close enough to show LPG a clear winner as least worst.

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937carrera wrote:

ajsimmo wrote:Good link, thanks.
I like the bit that shows one way that LPG is better for the environment:
Diesel = 132g CO2/km
Petrol = 120g CO2/km
LPG = 83g CO2/km

That's a massive difference, even allowing for slightly reduced mpg on LPG.

Slightly unfair though because the energy content of the fuels is different, so using the same volume of fuel per distance is not comparing apples with apples

Good find though - he must have had a good mole to find that.

Advanced Google skills

ahhh, my chemistry joke has gone unrecognised

You really can't ignore the energy density though

LPG 25-27 MJ / l
Petrol 34.2 MJ /l
Diesel 38.6 MJ / l

So, assuming the same conversion efficiency you need 48% more LPG and 13% more petrol than diesel to go the same distance

So energy content adjusted petrol becomes 136g / km and LPG becomes 123g / km against 132g / km for diesel.

Next of course in the evaluation is the relative conversion efficiency of the different fuels within their own engine type.

I was never a fan of the dash to diesel, and believe it makes sense to take full advantage of the lighter fractions coming off from refining crude, my comments here are primarily to try and get the engineering maths closer to reality (primarily because the implied assumptions behind the example in the webpage can lead to incorrect interpretation.) Think of this another way...... you LPG users know that one litre of LPG does not go as far as one litre of petrol.

Yes, well, sometimes. In reality, our WBXs very often run better on LPG than on petrol, and similar mpg results are often obtained. This can be because of inherent inefficiencies in the way a petrol carburettor works, and that petrol enters the engine as droplets of liquid compared to LPG entering as a much more readily combustible mix of gas and air. If the metering of LPG is also more accurately matched to demand, the whole process of turning fuel into motion can be markedly more efficient with LPG. That's why we don't often see the large real world differences that your figures would suggest.

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937carrera wrote:ahhh, my chemistry joke has gone unrecognised

No, it hasn't, Adrian (aged 13 3/4).


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That's why I referenced relative efficiency, the "cleanness" of the burn is another way of describing this effect.

Which is why although ethanol has a lower energy value than petrol, fuel consumption remains about the same, until you start running at blends in excess of about 10% when the efficiency gains from the oxygenate effect get overtaken by the loss in energy density.

By the time a car is running E85 (as Saab used to with their BioPower models) the increase in volumetric fuel consumption was much closer to the energy density difference.

I know what I know, and I also know that I'm only scratching the surface of the complexities.

ajsimmo wrote:

937carrera wrote:ahhh, my chemistry joke has gone unrecognised

No, it hasn't, Adrian (aged 13 3/4)

Aww, you made my evening