Thursday 3 October 2013

Fuelling Debate

There's been a kerfuffle about the imminent introduction of E10 fuel (10% ethanol) to the UK. There have been the usual "THIS EU DIRECTIVE WILL KILL YOUR CAR" horror stories, but an SKCC member found a report on the consequences online, so I read it. It's conclusion is that you can't use E10 in several million vehicles in the UK, but as usual that's not the full story - particularly where kit cars are concerned. Here's what I think, read & decide for yourself, but first a link to the report.

Right - I've read the report end to end - yes, still not much going on at work.
The first thing to note is this:-
"The study was funded by Olleco, a business which collects and refines waste cooking oil to be used as biodiesel in vehicles, which Mr Bailey found was a better option to be mixed with fuel than ethanol."

Not an un-biased view then.

Secondly, no practical experimentation was done under this report, all it does is report the findings of other reports & note comments found on internet forums.

There are several important areas it comments on:-

Fuel filter blockage caused by the ethanol dissolving fuel tank sealants & fuel hoses.
It says there is a small amount of evidence this happens, BUT the use of E5 & detergents already in petrol mean the chances are that if it was going to be a problem it would've happened by now.

The only repeat problems identified were with cars with sealant in fuel tank seams, in-tank hoses made from incompatible material & one make of camper where the filler hose was eaten by the ethanol in six months.

Our cars generally have welded tanks, so no sealant, have the outlet at the bottom, so no in-tank hoses, the filler hoses we’ll have to keep an eye on.

Galvanic corrosion (dissimilar metal corrosion) caused by the ethanol being a conductor & having water dissolved in it.

One of the few bits of actual science in the report says that Amal (they make carbs in the UK) has done soak tests & found that after a while a white powder collected in the float chamber & the brass jets showed signs of corrosion, they have changed materials to cure the problem. On aluminium it notes a number of reports, some say aluminium is fine, others say it’s not. Those that say it’s not, seem to regard tarnishing / discolouration as being unacceptable because it shows the Ethanol has “an effect” – significantly one report on fuel storage tanks states that aluminium is OK if it’s anodised, ethanol contains a lot of oxygen, tarnishing of aluminium is the oxidation of the surface – which when it’s done deliberately is known as …… anodising. There’s little actual info about brass, but it looks like it’s the zinc content rather than the copper that’s the issue & zinc is right at one end of the dissimilar metal table, just above magnesium, so that seems likely. GRP fuel tanks seem to be a particular problem, but they only seem to be used on boats.

On my car I have copper fuel lines, so I assume these won’t be a problem. When I built the car I earthed the fuel lines to prevent static build up, so that may help to reduce the electrical potential & therefore any galvanic corrosion, but I’m guessing there. I also have an aluminium fuel tank, but aluminium corrodes to a white powder, so I can look for that in the pre-pump filter, if you’ve not got one, now could be a good time to fit one.

Here the report states that as Ethanol contains about 35% oxygen, the air/fuel mixture will be wrong on carb engines, with EFi, it’s only when running open loop that there is an issue & the issue is that the exhaust temp could rise by up to 30deg C, which it sees as a problem only for the longevity of the cat, which I haven’t got.

So at worst it’s a rolling road session for a re-jet or a re-map. If you have carbs, get jets made of the more recent materials, though it’s worth noting that if the jets corrode, the holes get bigger, richening the mixture.

It says there is the potential for carburettor icing because the ethanol vapourises faster, lowering the inlet temperature more. It reports that internet forums dealing with running light aircraft on mogas (car petrol) suggest there’s a problem with carb icing. It goes on to say that in Canada they adjust the mix of petrol depending on the season to prevent carb icing, in the winter they add – ethanol.

So, inconclusive.

Deposit formation
The report says increased levels of inlet system and combustion chamber deposits have been reported with the use of E5 and E10 blends compared to E0. It goes on to say that those reports come from areas where they don’t add detergent so it’s unlikely to be a problem here.

So this shouldn’t be a problem either.

My conclusion is that the only real issue for my car is the flexible hoses. However, the major manufacturers all said that their cars made this century should be OK, all the fuel hose on my car was bought this century, so should be OK unless it was old stock when I bought it. But I had a similar problem with this when I built the car with some hoses not being compatible with unleaded. The first sign was a smell of petrol in the garage as the hoses soften & allow fuel to seep through, so I’ll be watching (sniffing) out for that.

Having said all this & concluded that the evidence is sparse, contradictory & apart from one or two instances (like the camper vans) not really serious, it goes on to say:-
Vehicles ten years old or older, carburettored vehicles (including powered two wheelers) and first generation direct injection spark ignition vehicles should not be fuelled on E10 unless the manufacturer can state the vehicles are compatible with E10.” Which I guess is a legal disclaimer.

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