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gone.2 02-15-2014 09:14 AM

MPG difference btw. E10 and E0 gasoline?
Has anyone documented any change in their MPG by switching from the E10 gas that's available everywhere to the straight stuff (E0) without alcohol? Percentage increase? Driveability? Let's hear all your stories!

doviatt 02-15-2014 09:36 AM

I've been experimenting with this. No reasonable data yet as other variables like temperature and weather are having a greater affect on my numbers.

My first tank of E0 bumped me from 41 to 47. I was stoked but I can not account for how much the E0 helped as that week warmed up a bit from single digit temps, and I noticed my driving technique was better also.

My second tank E0 again went up to 49 but, again warmer and I was paying attention to driving more because of the improvement.

3rd tank I went back to E10 expecting to see a drop. But, No. Stayed at 49.

I do believe my car likes it but I will have to do more controlled runs with better data collection like temps to measure any difference. In the meantime I should at least see the average start to come back up. In the spring time. Due to the weather. :-P

Cobb 02-15-2014 11:02 AM

I put 5 gallons of e85 in my tank of 10 gallons half of which was e10 and I want to say mpg went up as well as performance.

I saw upwards to a 10mpg increase,but that was a difficult test to repeat with all this cold wet, frozen weather on the east coast.

I think its due to more of the octane rating vs ethanol.

puddleglum 02-15-2014 11:22 AM

It's hard to make an accurate test just driving tank to tank because of all the variables. Plus, E0 is only available in premium as well so octane is higher. I tried a few tanks of premium but I have not been able to confirm any significant change on a tank by tank basis, so I have not made a change to premium.
What I can say is this province only officially made the change to E10 regular a couple of years ago, before that we were getting straight gas as far as I know. In the last two years my annual mileage has dropped 3-4% Considering premium is 10-12% more expensive, I see no advantage.

doviatt 02-15-2014 01:44 PM

Premium does no benefit if your car doesn't require it. Higher octane definitely doesn't increase mileage.
However Ethanol has less energy than gasoline. E10 has 10% of this. So every ten gallons of fuel, you are putting in one gallon of ethanol.
Older cars like mine don't know what to do with ethanol in their system. Newer flex fuel cars can sense when ethanol is present and change accordingly.
As it has been stated....hard to measure the difference without tight control over the test.

Cobb 02-15-2014 08:39 PM

This was the very reason I tried e85. I heard a car needs more fuel as e85 contains less energy so you burn more. Others say e85 makes more oxygen in the exhaust stream so your car leans out the afr and performance suffers. Others say e85 has the octane of 110 so for a high compression engine it will rock. How can it rock if its going to run lean? :eek:

Anyhoo I got an instant 9mpg, the engine seems to be quieter and the ima system acted as one would think. I refueled at half a tank and confirm the mpg increase during a brief spell of room temperature weather.

When the weather was a high of 32 and 70 miles I managed a dtc for lean condition.

D.O.G. 02-16-2014 12:15 AM

I've found that economy differences with E0/E10 depend on the engine.

I can buy E10 at about $1.50/litre, or E0 at plus 2 or 3 cents/litre. They're both 91 RON octane.

I found E0/E10 made little difference in "BoB" - 88 Mitsubishi 4G37 with a carby.

Same story with "Zed"- 81 Nissan L28 with EFI.

On the other hand, Baa - 98 Mazda BP-ZE with EFI, gives enough FE increase to more than cover the extra cost of E0.

I guess you weren't looking for a "try it and see" answer, but that's what I'd advise.

abently 02-16-2014 01:04 AM

I had always believed E10 would perform worse mileage wise as well until I saw this (trying to find a BSFC map for a K11 Micra) >

Doesn't make sense.... :confused:

D.O.G. 02-16-2014 05:18 AM


Originally Posted by abently (Post 411358)
I had always believed E10 would perform worse mileage wise as well until I saw this (trying to find a BSFC map for a K11 Micra) >

Doesn't make sense.... :confused:

From memory, the reason given for E10 being 2% cheaper than E0 when it was introduced in Australia, was the expected 2% reduced fuel economy.

Maybe cars produced after that, like the Micra used in this 2010 study, are specifically tuned to run better on E10?

Superfuelgero 02-16-2014 10:41 AM

My mileage is 8.5% better on E0 v. E10 (same octane) in the corolla. In the Civic its 11.9% better. This is over 4000 miles of driving alternating fuels in the Corolla, and 3500 in the Civic. The civic is higher than normal due to being able to stay in lean burn longer.

Innovate Newsletter:

Tuning Tip: Ethanol Content

We've had a few reports where users could not “nail down” their tune on the street with the LM-1. The AFR's would jump about 0.5 AFR across the WOT band even in the same weather conditions in the space of a few days. Instead of holding a tune, the engine seemed to slowly “yodel.”

Naturally the first thing to blame was the LM-1. But it turned out that the users filled up at different gas stations, sometimes filling up on gas that had 10% ethanol mixed in. As expected, when Schnapps is mixed with cars, things get a little complicated.

If ethanol (stoich AFR of 9) is mixed with gasoline (stoich AFR of 14.7) the resulting gas has a lower stoich AFR than 'pure' gasoline. As the fuel injection is tuned to mix a certain amount of fuel for a given amount of air, the resulting mixture would be leaner when using a fuel with lower stoich AFR.

This can be calculated:

sAFR = (%ofAdditive * sAFRadditive + (90-%ofAdditive) * sAFRgas) /100

sAFR is resulting stoich AFR
%ofAdditive is amount in % of mass of additive (ethanol) mixed in
sAFRadditive is stoich AFR of additive (9 for ethanol)
sAFRgas is stoich AFR of base gasoline (14.7)

For a 10% mixture of ethanol to gasoline by mass the resulting stoich AFR is 14.13

So, for an engine that's tuned to certain AFR at a certain load and RPM on straight gas, the resulting (gasoline equivalent) AFR when running the mixture can be calculated as:

new AFR = tuned gas AFR * (gasoline stoich ratio) / blend stoich ratio

An engine tuned to 12.5 gas AFR will run at the equivalent of 13 gas AFR with a 10% ethanol blend. This is what these people were seeing.

Of course, when running in closed loop, the engine will run at 14.13 AFR instead of 14.7. O2 sensors (incl. widebands) don’t measure AFR, but Lambda. Lambda is defined as actual AFR/stoich AFR. It's a ratio. In closed loop part throttle the engine is just running at Lambda 1.0, regardless of fuel. The same would be true for other Lambda values when running closed loop at WOT using a wideband. The engine would run at the tuned Lambda and everything would be fine. Open loop systems would need to be retuned for alcohol blends though.

Until next time... Keep On Tuning!

-Innovate Motorsports

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