Help me learn more about petrol
Discussion
Very interesting thread and I applaud your scientific approach. Unlike mine for adding acetone to fuel to get a boost in economy.
I took the approach that there are so many threads on forums across the internet extolling the benefits of adding acetone (and just as many not)
I decided to give it a go.
3 vehicles. One a 1.6 ti-VCT Ford Focus (variable cam timing, stnd FI) a high mileage Rover 400 1.4 (Stnd FI, cat etc... 175K on the clock) and a Honda VF500 Motorcycle of 1987 vintage (V4 motor, 4 carbs, 4 cams, 16v and 11,500 rpm). so a broad range of vehicles to test.
I tried different quantities per tank and different ways of adding it over a couple of years comparing tanks with it added and tanks without and came to the following conclusions:
Ford Focus, improvement in mpg = 0%
Rover 400, improvement in mpg = 0%
Honda VF 500, improvement in mpg = 0%
If anyone else has tried this with better/worse results, please let me know what you did, ratio mix etc... as I have a large container of acetone left and don't wear nail polish.
I would also like to point out that I have no affiliation with any major/minor fuel company or automotive manufacturer as often cited by advocates of Acetone in fuel flame wars to those who say it doesn't work.
Cheers
I took the approach that there are so many threads on forums across the internet extolling the benefits of adding acetone (and just as many not)
I decided to give it a go.
3 vehicles. One a 1.6 ti-VCT Ford Focus (variable cam timing, stnd FI) a high mileage Rover 400 1.4 (Stnd FI, cat etc... 175K on the clock) and a Honda VF500 Motorcycle of 1987 vintage (V4 motor, 4 carbs, 4 cams, 16v and 11,500 rpm). so a broad range of vehicles to test.
I tried different quantities per tank and different ways of adding it over a couple of years comparing tanks with it added and tanks without and came to the following conclusions:
Ford Focus, improvement in mpg = 0%
Rover 400, improvement in mpg = 0%
Honda VF 500, improvement in mpg = 0%
If anyone else has tried this with better/worse results, please let me know what you did, ratio mix etc... as I have a large container of acetone left and don't wear nail polish.
I would also like to point out that I have no affiliation with any major/minor fuel company or automotive manufacturer as often cited by advocates of Acetone in fuel flame wars to those who say it doesn't work.
Cheers
250GTE said:
Doubt it on E10, especially after Brexit. Who is lobbying for it ?
It's needed to meet government emissions targets.The Petrol Retailers Association are concerned.
http://www.ukpra.co.uk/pra-news/press-releases/
Trabi601 said:
V-Power Nitro Plus is 99 octane.
And E10 will hit the UK within a couple of years.
forgive me for going slightly off topic and being more than just a bit dim here ( I've got a Physics degree so know F-all about Chemistry!) but am I right in thinking its the bio-ethanol content of modern fuels that is responsible for rotting of older type rubber fuel pipes and seals etc? So anyone with an old ( sorry 'classic' ) car -or in my case old mower/strimmer/chainsaw etc is likely to suffer from leaky fuel systems if they increase the bio-ethanol content ? Or have I got completely the wrong end of the stick?And E10 will hit the UK within a couple of years.
I know a little about this so I'll chip in my tuppence worth. I'm a chemist and have done some further bits around refining, although my day job is in a different area of chemistry altogether.
Petrol is obviously not a single substance but is a blend of all manner of bits and pieces. The crude comes in to the refinery from the oil field or off the ship and goes through a series of pre-treatments before it goes to the first fractionating column. This takes out the heavy ends (residues, no use for fuels directly), light ends - that's the c1- c4 stuff, gases basically - and splits everything in the middle into the major fractions - naptha (c5-c6), kero (c7-c8) and diesel (c9-c10), sometimes a light cycle oil just between the diesel cut and the residue if the crude feed is at the 'sweet' end of the range i.e. high quantity of lighter fractions. The light ends get separated out to C1,2 for fuel to drive the refinery, either to produce syngas for heating or hydrogen for chemical treatments, the C3 is sold as propane and the C4 has a special use. The heavy ends is full of horrible rubbish like metals, suplhur, nitrogen, and needs intensive treatment to render it useful - you can still get the premium cuts from it, it just costs more and takes more effort.
The naptha is the primary gasoline fuel cut. Some of this goes direct to the gasoline blending pool (so-called straight run SR naptha), but as said the octane rating isn't great, only around 75 or so off the top of my head and it's quite volatile. So some might get cracked i.e. split into c1-c4s and the rest goes through a process called reforming, where the parrafinic (i.e. linear chain) molecules get re-arranged into a more unsaturated form, i.e. more branching, also generating some aromatics and olefins. This 'reformate' has a higher octane rating, higher energy density (more C-C bonds per molecule) and lower volatility, so more valuable as fuel.
Octane rating gets increased further by adding stuff like ethanol, but you have to be careful because like SR naptha this stuff is volatile. If the fuel has a vapour pressure that is too high, you get an effect in the fuel system called 'vapour lock' which I gather is essentially a bit like an air lock, so no fuel gets to the engine. This effectively limits how far you can improve the octane by adding in volatiles like ethanol.
Remember the c4 cut from the top of the column and the cracker? This is probably the most valuable stream on the refinery apart from hydrogen. c4s go through a process called 'alkylation', where they basically get added together to get c8s - octane. This alkylate is a highly branched c8, most desirably 2,2,4-trimethylpentane or iso-octane.
Your fuel is a mix of SR naptha, reformate, alkylate and oxygenates like ethanol, TAME, MTBE, ETBE etc (Google!). The blend properties are constrained by ISO standards for things like viscosity, vapour pressure, octane - there's more than one way to hit the spec and what proportions of what ingredients go in to make up the final blend will depend entirely on (i) the refinery feedstock, because not all crude oils are the same and (ii) refinery product mix and economics. For example if the refinery has a petrochemicals plant as a major customer, they're going to be skewed to producing c2-3 and c6-8 aromatics for the petrochem feedstocks, so there'll be a lot of cracking going on to convert up the residue. You'd expect more c4 by-product this way so the alkylate gets a little cheaper and offsets the over-supply of naptha into the cracker. One example, but the parameters that dictate product mix are very complex.
I'll check on this when I get in later as its been a while since I last looked at this stuff. That's basically where the fuel comes from and what's in it. But I can't help with what it means for combustion efficiency etc, that's a different field again.
Petrol is obviously not a single substance but is a blend of all manner of bits and pieces. The crude comes in to the refinery from the oil field or off the ship and goes through a series of pre-treatments before it goes to the first fractionating column. This takes out the heavy ends (residues, no use for fuels directly), light ends - that's the c1- c4 stuff, gases basically - and splits everything in the middle into the major fractions - naptha (c5-c6), kero (c7-c8) and diesel (c9-c10), sometimes a light cycle oil just between the diesel cut and the residue if the crude feed is at the 'sweet' end of the range i.e. high quantity of lighter fractions. The light ends get separated out to C1,2 for fuel to drive the refinery, either to produce syngas for heating or hydrogen for chemical treatments, the C3 is sold as propane and the C4 has a special use. The heavy ends is full of horrible rubbish like metals, suplhur, nitrogen, and needs intensive treatment to render it useful - you can still get the premium cuts from it, it just costs more and takes more effort.
The naptha is the primary gasoline fuel cut. Some of this goes direct to the gasoline blending pool (so-called straight run SR naptha), but as said the octane rating isn't great, only around 75 or so off the top of my head and it's quite volatile. So some might get cracked i.e. split into c1-c4s and the rest goes through a process called reforming, where the parrafinic (i.e. linear chain) molecules get re-arranged into a more unsaturated form, i.e. more branching, also generating some aromatics and olefins. This 'reformate' has a higher octane rating, higher energy density (more C-C bonds per molecule) and lower volatility, so more valuable as fuel.
Octane rating gets increased further by adding stuff like ethanol, but you have to be careful because like SR naptha this stuff is volatile. If the fuel has a vapour pressure that is too high, you get an effect in the fuel system called 'vapour lock' which I gather is essentially a bit like an air lock, so no fuel gets to the engine. This effectively limits how far you can improve the octane by adding in volatiles like ethanol.
Remember the c4 cut from the top of the column and the cracker? This is probably the most valuable stream on the refinery apart from hydrogen. c4s go through a process called 'alkylation', where they basically get added together to get c8s - octane. This alkylate is a highly branched c8, most desirably 2,2,4-trimethylpentane or iso-octane.
Your fuel is a mix of SR naptha, reformate, alkylate and oxygenates like ethanol, TAME, MTBE, ETBE etc (Google!). The blend properties are constrained by ISO standards for things like viscosity, vapour pressure, octane - there's more than one way to hit the spec and what proportions of what ingredients go in to make up the final blend will depend entirely on (i) the refinery feedstock, because not all crude oils are the same and (ii) refinery product mix and economics. For example if the refinery has a petrochemicals plant as a major customer, they're going to be skewed to producing c2-3 and c6-8 aromatics for the petrochem feedstocks, so there'll be a lot of cracking going on to convert up the residue. You'd expect more c4 by-product this way so the alkylate gets a little cheaper and offsets the over-supply of naptha into the cracker. One example, but the parameters that dictate product mix are very complex.
I'll check on this when I get in later as its been a while since I last looked at this stuff. That's basically where the fuel comes from and what's in it. But I can't help with what it means for combustion efficiency etc, that's a different field again.
monoloco said:
Trabi601 said:
V-Power Nitro Plus is 99 octane.
And E10 will hit the UK within a couple of years.
forgive me for going slightly off topic and being more than just a bit dim here ( I've got a Physics degree so know F-all about Chemistry!) but am I right in thinking its the bio-ethanol content of modern fuels that is responsible for rotting of older type rubber fuel pipes and seals etc? So anyone with an old ( sorry 'classic' ) car -or in my case old mower/strimmer/chainsaw etc is likely to suffer from leaky fuel systems if they increase the bio-ethanol content ? Or have I got completely the wrong end of the stick?And E10 will hit the UK within a couple of years.
I had an issue with a Mk1 MX5 due to running it on E10 when on a Euro Tour - the ethanol destroyed the seal on the fuel tank drain plug and I lost nearly a full tank of unleaded into the street outside the Grand Hotel in Torquay.
Some interesting things on fuel blends from my line of work...
The RON quoted at the pump is the minimum, not the actual or anything else. Reference fuels (as used in test houses) are very tightly controlled in terms of RON and other factors for characterising engine hardware and are quite expensive, fuels that are bought at the forecourt are much cheaper because the base stock is not as tightly controlled (and nor are the additives). This means that there can be some variability in different batches which still meet the same legislative criteria. What typically tends to happen so far as I can tell is that the base stock is blended and the RON is "topped up" with the ethanol content which can lead to 95 being anywhere between 96 and 98 RON on the road and accordingly a difference in calorific value stoichiometry. This is worse in markets like Brazil where they sell fuels with higher ethanol content (E26 for example) where the base stock can be (almost) any old s
t. In terms of energy content, an E0 95 RON road fuel is going to be in the range of 42-43 MJ/kg LCV and a stoich AFR somewhere in the region of 14.6:1. For an E10 fuel the LCV will come down to somewhere in the range of 41 MJ/kg and the stoich AFR around 14:1.
The LCV change is one of the major impacts to fuel economy. Example: fuel A has an LCV of 42.5 and fuel B is 41 - this means that 3.5% more fuel is required for fuel B to extract the same amount of energy that 1kg of fuel A has.
There are lots of things to consider from an emissions point of view. For example, the constituent components of the fuel will result in a boiling curve shown as percentage mass against temperature. The final boiling temperature of the fuel can be anywhere from 170°C to over 200°C. With PN being the major focus for gasoline engines with coming legislation, final boiling temperature has been a bit more important to consider than it might have been in the past. For example, if the fuel spray impinges on the liner, the liner temperature doesn't exceed 170°C so not all of the fuel is immediately vaporised. This is the stuff that tends to cause problems with PN emissions, and it is the same for any surface impingement whether that is the piston, liner or cylinder head or even the injector surface. As you can imagine, the problem is worse still when the engine is cold.
The RON quoted at the pump is the minimum, not the actual or anything else. Reference fuels (as used in test houses) are very tightly controlled in terms of RON and other factors for characterising engine hardware and are quite expensive, fuels that are bought at the forecourt are much cheaper because the base stock is not as tightly controlled (and nor are the additives). This means that there can be some variability in different batches which still meet the same legislative criteria. What typically tends to happen so far as I can tell is that the base stock is blended and the RON is "topped up" with the ethanol content which can lead to 95 being anywhere between 96 and 98 RON on the road and accordingly a difference in calorific value stoichiometry. This is worse in markets like Brazil where they sell fuels with higher ethanol content (E26 for example) where the base stock can be (almost) any old s
t. In terms of energy content, an E0 95 RON road fuel is going to be in the range of 42-43 MJ/kg LCV and a stoich AFR somewhere in the region of 14.6:1. For an E10 fuel the LCV will come down to somewhere in the range of 41 MJ/kg and the stoich AFR around 14:1.The LCV change is one of the major impacts to fuel economy. Example: fuel A has an LCV of 42.5 and fuel B is 41 - this means that 3.5% more fuel is required for fuel B to extract the same amount of energy that 1kg of fuel A has.
There are lots of things to consider from an emissions point of view. For example, the constituent components of the fuel will result in a boiling curve shown as percentage mass against temperature. The final boiling temperature of the fuel can be anywhere from 170°C to over 200°C. With PN being the major focus for gasoline engines with coming legislation, final boiling temperature has been a bit more important to consider than it might have been in the past. For example, if the fuel spray impinges on the liner, the liner temperature doesn't exceed 170°C so not all of the fuel is immediately vaporised. This is the stuff that tends to cause problems with PN emissions, and it is the same for any surface impingement whether that is the piston, liner or cylinder head or even the injector surface. As you can imagine, the problem is worse still when the engine is cold.
Trabi601 said:
monoloco said:
Trabi601 said:
V-Power Nitro Plus is 99 octane.
And E10 will hit the UK within a couple of years.
forgive me for going slightly off topic and being more than just a bit dim here ( I've got a Physics degree so know F-all about Chemistry!) but am I right in thinking its the bio-ethanol content of modern fuels that is responsible for rotting of older type rubber fuel pipes and seals etc? So anyone with an old ( sorry 'classic' ) car -or in my case old mower/strimmer/chainsaw etc is likely to suffer from leaky fuel systems if they increase the bio-ethanol content ? Or have I got completely the wrong end of the stick?And E10 will hit the UK within a couple of years.
I had an issue with a Mk1 MX5 due to running it on E10 when on a Euro Tour - the ethanol destroyed the seal on the fuel tank drain plug and I lost nearly a full tank of unleaded into the street outside the Grand Hotel in Torquay.
battered said:
Anecdotally - I had a 3 month spell of work in France. I took my ratty old Astra out there and ran it on E10 because it was cheap. I got the distinct impression that the fuel consumption was about 5-10% down for similar running, which wrote off the cost saving.
Yes, a friend of mine shuffles his family too and from Geneva in one of those old Chrysler people carrier thingies, he is convinced he is better off putting 98 octane petrol in there. No perceptable performance diff on the bus , but pays for itself in better economy (or less worse).The OP is right to be wary of most of the stuff on the internet, so much 'knowledge' from forum experts! I applaud you trying to understand a bit more about things. I did try to do something similar on the MLR years ago but didn't get very far.
I have only a layman's knowledge of such things, but Mrs LLA is a qualified chemist (not Boots etc., you get a swift kick in the nads for that patter with her!) and worked in strategic polyolefin procurement for an oil major for many years buying, yes, additives for road fuels. She had to know a fair bit about the fuel value chain and how to maximise things balancing additive prices, base stock availability/price, seasonal demand, plant efficiency etc.
I'll keep an eye on this thread and if there are any specific questions she might be able to help with I'll see if she has any insight.
I have only a layman's knowledge of such things, but Mrs LLA is a qualified chemist (not Boots etc., you get a swift kick in the nads for that patter with her!) and worked in strategic polyolefin procurement for an oil major for many years buying, yes, additives for road fuels. She had to know a fair bit about the fuel value chain and how to maximise things balancing additive prices, base stock availability/price, seasonal demand, plant efficiency etc.
I'll keep an eye on this thread and if there are any specific questions she might be able to help with I'll see if she has any insight.
battered said:
Anecdotally - I had a 3 month spell of work in France. I took my ratty old Astra out there and ran it on E10 because it was cheap. I got the distinct impression that the fuel consumption was about 5-10% down for similar running, which wrote off the cost saving.
Fuel consumption was down? Wouldn't that increase the cost saving? Or do you mean fuel economy was down?
xRIEx said:
battered said:
Anecdotally - I had a 3 month spell of work in France. I took my ratty old Astra out there and ran it on E10 because it was cheap. I got the distinct impression that the fuel consumption was about 5-10% down for similar running, which wrote off the cost saving.
Fuel consumption was down? Wouldn't that increase the cost saving? Or do you mean fuel economy was down?
Some absolutely fantastic replies here folks! Far too many (and too much) to quote individually, but rest assured they've all been read and taken on board. I've already learnt a lot, and have a lot more I can read up on now. Thank you. 
Feel free to keep it coming! PH ranks very highly on Google, so it'd be nice to have a decent informed thread on page 1 rather than the guff that's there presently. 
Feel free to keep it coming! PH ranks very highly on Google, so it'd be nice to have a decent informed thread on page 1 rather than the guff that's there presently. battered said:
Anecdotally - I had a 3 month spell of work in France. I took my ratty old Astra out there and ran it on E10 because it was cheap. I got the distinct impression that the fuel consumption was about 5-10% down for similar running, which wrote off the cost saving.
(Also anecdotally) A mate and I took my old 1.2 Nova to France in about 1991.I can't recall what we put in it. Probably Super-Duper sans plomb, knowing us. Don't know what RON it was, but the car seemed tangibly up on power.
One V-max episode saw an interesting number, even allowing for a speedo error of 15% it was WAY more than it should have been.
So much so that a photo was taken.
It was definitely pretty flat, and In wasn't aware of a tailwind.
Were French fuels better (in terms of energy density) back in the day?
battered said:
Aromatic hydrocarbons (with rings, eg benzene) are very energy dense, less volatile than linear HCs of the same C-chain length, and reduce knocking (not entirely sure why, prob less volatility).
As knocking is the product of detonation (rather than ignition) the reduced volatility would presumably be crucial to aromatic hydrocarbons reducing knocking. I'd hazard that the ring structure would provide a more stable molecular bond compared to an equivalent linear chain, thus making it less susceptible to breaking under increased temperatures driven by compression.A quick question about diesel for the chemists - I understand that diesel is engineered to have a low octane rating for the specific purpose of detonating easily, and that the equivalent performance rating to a petrol's RON value is the cetane rating. What does this actually mean? As in, if a high octane petrol is more resistant to detonation, what makes a higher cetane rating diesel better than its lower rated equivalent?
Here in Scotland and down in the North of England, most petrol comes from Grangemouth,
It's a base mix which is (so I've been told) that's the same for each brand. Some brands than put a mixture of additives and cleaners in the downstream tanks, which is what you pay for from a "premium" brand. This varies so different brands effective different cars in ways. I do wonder if there is sometimes a Placebo" effect and the car performs better because you expect it too, although higher RON will give you a boost.
It's a base mix which is (so I've been told) that's the same for each brand. Some brands than put a mixture of additives and cleaners in the downstream tanks, which is what you pay for from a "premium" brand. This varies so different brands effective different cars in ways. I do wonder if there is sometimes a Placebo" effect and the car performs better because you expect it too, although higher RON will give you a boost.
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