Is using E10 in your car worth the 2 cents per litre saving?

[facthunter]

I wouldn't run E10 thinking I was getting value for money. Ethanol has much less energy for vol than ordinary paraffin type fuels. There are also some risks with fuel system components.

 

Some engines 'recognise" the higher octane fuels and retune themselves to take advantage of it.

 

Diesel stinks and often you are getting it all over your hands when you refill. This doesn't go down well with the ladies going to an occasion. European models are generally more high tech and fuel efficient. The small size and high output of some is a slight cause for concern, requiring everything be right ie expensive oil, on time servicing and operations in high load /temperatures, with larger payload vehicles.

 

Tiny cars SHOULD do good mileage as they are tiny. If you load them up and put a trailer on they aren't that economical then.Nev

 

 

[Ultralights]

years ago when i had a turbo petrol subaru forester, the manual stated any fuel octane above 95, i usually ran it with 98. but one day, the independent servo up the road advertised that E10 was also 98 octane. on the usual 98 unleaded, i would get around 450Km to a tank, and plenty of power. but on the 98 E10, i was lucky to get 300Km from that tank, and at full throttle and boost pressures, the ECU would retard the timing and other controls to the point where it would no longer accelerate. felt like the more throttle you gave it, the more someone was ripping on the handbrake. i decided that the cost saving for using the E10 was no where near worth the loss of economy and power. either that, or i just happened to get a bad batch of E10, either way, never used is since in a petrol car. (also, im not a fan of mandating a food substance to make automotive fuels)

 

 

[old man emu]

You will mostly experience fuel consumption reduction when you use E10 as the ethanol fuel component has roughly half the calorific energy of 91. It's not unusual to see a 5% reduction in fuel economy. I won't comment about the savings using E10, other than to say there is no such thing!Vev

I think you've hit the nail on the head by highlighting the calorific difference between E10 and pure fuel. There's also the added uncertainty of exactly how much ethanol is in each batch of E10, since the placard on the fuel bowser says "up to 10% ethanol".

 

If you compare the price of E10 to pure fuel, the E10 is 2% cheaper per litre than pure fuel. Let's assume that E10 costs $1.22 per litre and pure fuel costs $1.24.

 

My car has a capacity of 60 litres, therefore a tankful of E10 costs $73.20 -v- $74.40 for pure fuel. So I would save $1.20 per tankful.

 

On pure fuel, I get 10 km/l, or 600 km per tankful. If E10 produces a 5% reduction in fuel economy, that's 9.5 km/l, or 570 km per tankful. I'm 30 km short.

 

To go 30 km @ 9.5 km/l, I need 3.2 litres, which would cost me $3.85. I would be ($1.20 - $3.85 = -$2.65) worse off for having used E10.

 

OME

 

 

[facthunter]

I don't think anyone who has looked into the figures would disagree with you OME. It is elements of the sugar industry pushing it. Brazil has even used 100% ethanol in cropdusters. When it burns the flame is almost invisible which can be a bit of a safety hazard. Alcohol and petrol don't mix. Extra chemicals must be added. to achieve it. Alcohol is also hygroscopic. This can be good and bad.Nev

 

 

[old man emu]

I had a thought. Since city driving is a lot of stop/start, with the starting bit needing lots of energy, wouldn't it be wiser to use pure fuel for day-to-day driving in the city, then use E10 for trips on the open road?

 

On the open road, the main work that the engine has to do is overcome Drag from the road and air resistance to maintain a constant speed (hilly terrain excepted). Therefore, the difference in calorific value between E10 and pure fuel wouldn't be so noticeable.

 

OME

 

 

[Guest john]

E10 is a ratshxit fuel as it will even stuff up the composite float in a motor mower. So if you want to buy a cheap shxt fuel & put it in your vehicle , then be prepared for the unknown costs soon after. Under no circumstances should it be used in an aircraft unless you want to practice compulsary forced landings after the engine fails.

 

 

[old man emu]

I did some googling and found these energy values for common fuels:

 

The calculation was:

 

Mj/kg x (1/ density)

 

The energy values I used were the LHV which is known as the lower heating value (net calorific value (NCV) or lower calorific value (LCV)), andis determined by subtracting the heat of vaporization of the water vapor from the higher heating value. This treats any H2O formed as a vapor. The energy required to vaporize the water therefore is not released as heat which can be used by the engine to produce power and goes down the exhaust pipe to become visible as steam as it condenses outside the system.

 

PETROL: 44.448 MJ/kg x (1/0.77) = 44.448 x 1.35 = 60 MJ/l

 

DIESEL: 42.791 MJ/kg x (1/0.832) = 42.791 x 1.2 = 51.43 MJ/l

 

ETHANOL: 26.952 MJ/kg x (1/0.789) = 26.952 x 1.27 = 34.16 MJ/l

 

LPG: 46.607 MJ/kg x (1/0.55) = 46.607 x 1.82 = 84.74 MJ/l

 

OME

 

 

[Rastus]

E10 is a ratshxit fuel as it will even stuff up the composite float in a motor mower. So if you want to buy a cheap shxt fuel & put it in your vehicle , then be prepared for the unknown costs soon after. Under no circumstances should it be used in an aircraft unless you want to practice compulsary forced landings after the engine fails.

I won't use ethanol blend in anything.

 

Just had a thought: If a motor needs to burn more E10 than straight fuel, does that mean a motor with a carby will run too lean? I mean a fixed carby like an older car or mower.

 

We had a Mazda E2000 light truck (Carby) where I work which we ran on E10. It had 2 engine failures within 20,000 Km. Not sure if it was the E10 or the fact that it was seriously underpowered and had to be thrashed pretty hard to keep up with other traffic.

 

 

[Downunder]

Alcohol fuels have a higher octane than petrol?

 

If E10 is 91 octane, does this mean the actual fuel proportion has an octane less than 91 and the ethanol bumps it up?

 

 

[old man emu]

Alcohol fuels have a higher octane than petrol? If E10 is 91 octane, does this mean the actual fuel proportion has an octane less than 91 and the ethanol bumps it up?

You have to remember that Octane Rating has no actual meaning of itself. It is simply a way of saying how resistant the fuel under examination is to detonation in comparison to a reference fuel which is a mixture of heptane and iso-octane. The octane rating of gasoline is measured in a test engine and is defined by comparison with the mixture of 2,2,4-trimethylpentane (iso-octane) and heptane that would have the same anti-knocking capacity (resistance to detonation)as the fuel under test: the percentage, by volume, of 2,2,4-trimethylpentane in that mixture is the octane number of the fuel. Therefore, using this method of comparing fuels, the maximum octane value is 100, which represents means that the fuel under test has the same anti-knock capacity as 100% iso-octane. Octane ratings are not indicators of the energy content of fuels. They are only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner.

 

Where the octane number is raised by blending in ethanol, energy content per volume is reduced because we have seen above that ethanol has about half the energy per litre as petrol. Ethanol has an octane of 113 (don't ask how a fuel can have an octane rating which is equivalent to more than 100% - that's a subject for another discussion), so if you mix 90+% of petrol which has a higher octane rating than 91 with up to 10% ethanol, you'll end up with a fuel that has an octane rating of 91.

 

At this stage, let's also leave RON (Research Octane Number), MON (Motor Octane Number) and AKI (Anti-Knock Index = [RON + MON]/2) out of the discussion, since RON and MON are determined by two different, but basically similar, techniques.

 

OME

 

 

[facthunter]

The point is you don't save money and may/will raise concerns about reliability and maintenance costs. Why use it if you don't have to? Rotax already have a problem with their carb floats getting soaked and sinking causing flooding. . Avgas is the only fuel that meets a required standard. The rest is a gamble to some extent.

 

Any carburetter tuned for ordinary hydrocarbon fuel will run leaner with any ethanol in the fuel. 10% ethanol will be roughly 5% leaner 1/20 . Adding premix oil could do the same as there are viscosity considerations there, but the effect is the same. Life in storage is an issue too. Nev

 

 

[Guest AAA]

As a lot of cars have stood unused for a couple of months will we see a large number of breakdown due to the ethinol separating in the tank ?.

My lawn tools died after using ethanol fuel by mistake, they managed when in use through summer, but after the winter storage with that fuel evaporating.

They all went into the garbage. I tried mending them but was unsuccessful.

spacesailor

[red750]

Slightly off topic because I have never used E10 petrol. My old AU Falcon is only fed 91 octane. On Wednesday, before the price jumped 35c, I put in 22 litres at 95.9c./l. With the Woolies discount cardit cost me $19.99. The Distance to Empty showed 248 km. I did a bit of running around shopping, and when I finished for the night the DTE said 208 km. On Thursday, I had to go to Elwood to pick something up for the missus, then I went to Moorabbin Airport.Drove around a bit looking at the planes and taking photos. When I got home, the missus said "I need you to go to the hospital chemist at Box Hill to pick up some special medication." From Google maps, in round figures, the total trips were about 60 km. The DTE said 224km. I didn't add extra fuel.

[old man emu]

The way you drive, and where you are driving in will greatly affect the vehicle's calculation of distance to empty. If I drive at about 2500 RPM on a freeway, I can see the total distance from a tankful (sum of distance traveled plus distance to empty) increase quite a bit over a 20 km run. Short runs with traffic light stops cut the total distance from a tankful to pieces.

[ClintonB]

My great Wally was run on E10 most of the time for 8 years. When I did put premium in it I got less mileage. Same with our family car Kia carnival with 3.5V6

i run the wife’s Honda on premium because it’s a little high performance engine and all mowers, boat motor, whipper snippets and the Bushbaby 582.

some 30c litre difference in country or when we travel to the coast.

 

[Bruce Tuncks]

My ASX has a bar-indicator of instantaneous fuel rate, and it sure does make a difference how heavy your foot is. Of course we already knew this, and a good tip for economy driving is to hardly ever use the brakes. Braking represents energy being thrown away.

Another tip is to have tyres 5psi harder than the book says. Tyre-flexing is also energy thrown away.

Once I worked with a guy who complained about the cost of fuel to get to work. He had often overtaken me on the country road we used, and he was amazed when I told him he could save big money by slowing down to 80 kph.  Well he saved $20 a week and was very grateful. Apparently the $20 nearly doubled his discretionary money. Yep, going fast is expensive too.

[old man emu]

Also most people boast about the horsepower or kilowatts of their engines, but maximum power is only attained at the top end of the rev range. What is more important is the rev range around maximum torque, which will be at the lower end of the rev range.

 

This is not knew to pilots. We all know that to climb we need high revs, but to cruise along, we come back down the rev range. A constant speed prop give us better control of torque supply to the prop. In a car, most people forget that between the engine and the drive wheels there's a box of whirring cogs that are the heart and soul of fuel economy. What that box of cogs does is match the torque produced by the engine to the resistance of the drive wheels to the inertia of the car. If you graph torque -v- RPM for most modern cars, you will find that the slope of the graph initially rises steeply from idle revs of 750 - 800 to a plateau level roughly between 1500 and 2500 RPM. 

 

For best fuel economy, one should initially allow the vehicle to start moving slowly using its idle RPM, and as it begins to move, gently raise the RPM to around 2000 and hold them there. The gearbox, talking of automatics here, will make the changes as the torque required to overcome the car's inertia reduces and road speed increases. Once the desired road speed is reached, the required torque remains constant and the fuel consumption is minimised.

 

But that's old news to even student pilots.

 

Bruce's mate probably didn't use most of his extra $20 going faster than 80 kph. I'd bet that he was the type of driver who used sling-shot starts - foot to the floor from the word "Go!". Over-revving the engine for moving off, early gear changes and excessive use of the accelerator pump in the carby all suck fuel big time. The moral is, "slow and steady produces more discretionary spending power".

[Bruce Tuncks]

Believe it or not, this guy actually had a master's degree in engineering from Iran. In reality, he knew less than any Australian petrol-head kid I knew.

Gosh it's easy to hand out degrees. His whole family emigrated to Australia by converting to a non-islamic  religion and then claiming the likelihood of persecution if they stayed.

 

Last I heard of him, he had got an  executive-level public service  job in Canberra and would be doing very well, and his almost complete lack of any engineering knowledge would not be hindering him at all. Mind you, he did have the gift of conversation. I quite liked him.