Read My Conversion to E85 Page 1

16 Jun 2008.

I have decided the car is running lean.
The car has less power at low rpm and more power at higher rpm, above 3000.
The car goes up hill at low revs when cold better than hot: this is when the choke is on, and fuel mixture would be richer.All the literature I have read is saying 30% extra fuel is required to make the correct A/F mixture.
The injector control box has settings 0 to 10: 0 is nil, 10 is 27% extra. It was set on 5.
I have changed it to 8: this is about 22 % extra fuel instead of 13.5%.
I did not wind it all the way because I may need to run normal petrol occasionally.

Low rpm power 1000-2000 is noticeably improved.


18 Jun 2008.
I have increased the compensation on the box to 10 or 27% extra fuel.
I wonder if the fuel injectors are capable of delivering this extra quantity.
I took the car for a quick test run and it feels good. The only difference is more power at 3000+rpm. At low rpm it feels the same as normal unleaded.
The engine has a growl when it is revved up: it's fun to drive.
This is still the first tank of E85; next tank I will drive normally, less engine revving and testing. I expect the economy to be poor on the first tank of fuel. I am reasonably sure the engine was running too lean. The next tank full will be a good indication of economy.

19 Jun 2008.

My petrol tank emptied down to a quarter full today.
I have refilled the tank with E85, adding another 40.95 litres.
It cost $43.00; E85 was $1.05. If I had used regular unleaded petrol priced at $1.65 per litre, it would have cost $67.56.
I traveled 383.4 km; the first 150km of this was on a 13.5% increase in injection. The car did not perform as well as usual at this level, and I increased injection to 22%. I traveled about 100km at this level then increased it to 27%.
Only the last 134 km were done with the closer to optimum injector setting for E85 AFM. (air fuel mixture)

20 Jun 2008

How much ethanol is in the fuel tank?
I have been thinking about the fuel in the tank, particularly the % of ethanol in the fuel.
If I have filled up my tank with E10 many times, say 5 or 6 in a row It would be reasonable to expect that I have a fuel tank with 10% ethanol in it.
If I have a tank that is 1/2 full of regular unleaded 87- 91 octane and fill with E10 then my tank will be 5% ethanol.
(0.5*0)+(0.5*10) = 5

If I have a ¼ of a tank of E10 (10% ethanol) and I fill up with E85 (85% ethanol), the fuel in the tank is  (0.25*10)+(0.75*85) = 66.25%. ethanol

If I add ¾ of a tank of E85 again when I get down to ¼ the new % is  (0.25*66.25)+(0.75*85) = 80.31%.
Repeat this two more times  83.82%, 84.70%.
After filling up four times from ¼ of a tank with E85 I am running fuel with 84.7% ethanol.

27 Jun 2008 am

I have added a table in What's in the tank, to try to show changes in cost of fuel and alcohol content of fuel in the tank.

27 Jun 2008pm

cost of fuel and alcohol content of fuel in the tank

This table shows the changes in economy that have occurred. The tank was filled with E85 three times at $1.05 per litre, taking Ethanol concentration to 84%, then because of location and no E85 pump within 200km, E10 at $163.7 p/L was added and the ethanol was diluted down to 43%. The litres used per 100km was the same at 43% as it was at 10%. The $ per 100Km was always better when extra ethanol was in the tank. Best so far was 23% improved on a tank of 84% ethanol.

I will continue to calculate and publish fuel economy and the changes in performance of the car.

07 July 2008

refer to new fuel economy table in

Table of Economy using E10 and E85 blended in fuel tank.

Interesting % difference $ compared to E10.

So far every blend of higher alcohol content has saved me money.

The last two figures for approx 82% ethanol saved 29%.
Savings since Flex Fuel conversion is $159.
Kilometers travelled 2804
Litres of fuel used 294.
I have had the conversion for 3 weeks and it is well on its way to paying for itself.

17th July 2008

Filled up again this morning, car was on low fuel warning since last night. I noticed that the petrol station in town (Shell) was $1.669 per litre for ULP and $1.639 for E10. I put in 47.5 litres of  E85 at $1.05 per litre. It cost me $49.90 at the bowser and when it paid they gave me $10 off, I use the station rewards card ( $10 after every $200 spent ). If I had filled with ULP it would have cost me $79.30.
I have done the litres / 100km economy calculations again. click here to View the  tables.  
The car ran at 19% improvement on cost per 100km compared to E10.
I am considering changing my fuel filter, it is recomended to change after 1000km on a couple of the other sites I have looked at. I dont think its too bad otherwise I would have changed it already. I think because the car has always used E10 the problems from water in the fuel that others who have only used ULP have experienced probably won't occur. The 10% alcohol in E10 would have been absorbing the water into the fuel rather than it building up in the tank.


25th July 2008
Almost same fuel economy and saving as last fill. Table of Economy using E10 and E85 blended in fuel tank

Still experiencing some feathering at cruise, thats with the throttle only open enough to maintain speed.
It has occured at different speeds, at 80, 100, and 110km/h.
Car is smooth on take of and when power is applies at other speeds.
It may be timing/AFM changes occuring when car is cruising, computer leaning out mixture and advancing timing to save fuel.
Car has a power band at about 3000 to 3500 reves, higher in higher gears.

Going to auto parts store to check out thinner oil and discuss spark plugs.