Adding fuel to the fire

The increased ethanol content of petrol in the UK is causing all sorts of issues, and Frank says you need to start paying attention in this area

Published:  12 September, 2022

COVID-19 and the last two years may have reset how we, dare I say, plan, for the future. If the pandemic wasn’t enough, the events of the last four months have only reaffirmed the need to think further ahead than we have been used to doing. The war in Ukraine has affected parts supply as well as fuel stocks and delivery.
    
I have chosen to revisit bioethanol fuel and its effect on vehicle design and servicing. I’m not a farming expert but I do know that Ukraine is a supplier of raw ingredients, such as wheat, maze, and sugar cane. The UK has quite recently introduced E10 at our pumps. Fortunately, E5 is still available, reserved for our high-energy fuels. I’m glad about this on a personal level, because that is all I ever use.
    
I do not buy into some of the statements regarding the introduction of bioethanol fuels as they have their roots with political initiatives, reducing C02 levels, reducing farming subsidies and overproduction waste, and replacing fossil fuel production.
    
The process of creating bioethanol fuel by alcoholic fermentation is above my pay grade, but I wonder what the hidden pollution cost of farming, transportation and actual production is?
I suggest you look at biomass fuels for electricity production, which is one of the most dishonest clean energy claims. I am often found cycling through north Lincolnshire, where I am well-placed to watch the endless trains on their way to Drax power station. Biomass is wood or trees, a great deal comes from North America. It’s worth a thought while driving EVs!
    
Ethanol is an organic hydrocarbon which like petroleum consists of carbon molecules. The ethanol chain is comprised of two carbon molecules, each supporting three hydrogen atoms and a hydroxyl group; Oxygen with one hydrogen atom. Bioethanol can be identified as ethanol produced from biomass (a renewable carbon source),  or waste material, vegetables, timber (trees) straw, or plant-based material. My last statement is the biggest objection to claims of what makes a renewable energy source. Biomass fuel is combusted much faster than its source can be renewed. In short, trees do not grow quickly.
    
In Europe under DIN EN 228, 5% ethanol is allowed in petroleum fuels without additional labelling on the pump, whereas 10% and above must be identified. Percentages up to 85% are possible but only with highly modified vehicles.
    
Ethanol has a fixed boiling point of 78°C. This has a direct effect on the combustion process, especially from cold. Therefore, fuel delivery quantity and ignition adjustment are paramount to successful drivability. First generation biofuels compose of oil or sugar-based plants into diesel fuel by pressing and esterification. Sugar-based plants are converted into ethanol by a fermentation process.
    
Second generation biofuels are produced from a variety of energy sources including, organic waste, straw, wood, agricultural waste, old timber, low grade forest, including land set aside for future growth, and fast-growing plant material.
    
Low grade forest growth is normally 15-20 years. Renewable carbon source? Here come the politics. Plants convert atmospheric CO2 into biomass, this renewable energy source can then be subtracted from vehicle emissions. It even has a political expression, carbon credits, or carbon offset. It is accepted that bioethanol fuels have less calorific value than petroleum, however the increase in combustion cylinder pressures make up any differences in power output.

Effect
Autarkic cold starting, or poor start combustion has now been overcome without the need for preheaters, by re-introducing a cold start manifold injector n17, alloy manifolds and retardation of the ignition profile. Additional cylinder bore treatments will help counteract bore wash during adverse low temperature conditions. There is however a much-modified servicing requirement due to oil pollution increase. Oil replacement occurs every 15,000 kilometres or 9,000 mils or 12 months. Ethanol fuel is highly corrosive with respect to copper, aluminium, and rubber, therefor it is not advisable to operate vehicle’s non-bioethanol compliant.
    
Bioethanol fuels have a similar effect on valve seats as unleaded fuels did on their introduction several years ago. Further attention by Audi in addressing the combustion pressure increases focused on the design and strengthening of the con rods, big end bearings with an additional aluminium layer, and piston crown design.
    
The vehicle electronic control system must have a fuel quality sensor g446. This is fitted in the primary fuel supply line. This is necessary for correct adjustment to varying ethanol percentage. Its function is a capacitive change due to the two-bioethanol content. The sensor outputs a frequency between 55hz equalling 0% bio and 150hz equalling 100% bio.

Improvement
To improve cold start, Audi took full advantage of their multi-injection control system, with one injection event on the intake stroke. This period corrects for the additional cold start fuel requirement, with two injection events occurring on the compression event, with the timing shifted closer to the ignition point. This is augmented by a fuel pressure of 150bar. A conventional gasoline vehicle would have between 65 and 90bar.
    
There has been some speculation over adverse injector performance with bioethanol fuels. We at ADS have experienced what I would describe as an unusually high number of injector-related problems in recent months. With fuel delivery pressures of 350 bar and above, Care should be taken before attributing symptoms and cause. However, I do understand from a great friend and industry expert, that Bosch are experiencing filter baskets dissolving and or restricting fuel flow through the injector resulting in engine failure. Porsche is another manufacturer experiencing premature engine failures, although I have no evidence that there is any connection between these causes.
    
Other more obvious considerations with injectors focus on the obvious fact that the pintles are mounted directly into the combustion area. Therefore they subject to combustion related deposits. Also, pintles may open out, but not in.
    
Do not pre-judge my comments in this topic as negative to recent developments. I have been an automotive engineer for over 50 years. As such, I take a wider, fact-diven view of the rapid changes I have witnessed, including the comments at the beginning of this subject.

As a footnote, BMW and KIA have given directives to their dealership network to recommend named-brand gasoline only, without ethanol content.




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