Alternative fuels
Ethanol is an alcohol-based fuel made by fermenting and distilling crops that have been broken down into simple sugars. While it can be made with other crops such as sorghum, sugar cane, or sugar beets, in the united states it is primarily made from corn.
A bushel (56 lbs) of field corn will yield 31.5 pounds of starch or 33 pounds of sweetener or 2.8 gallons of fuel ethanol plus 1.5 pounds of corn oil plus 16.1 pounds of high-protein feed.
E85 fuel is 85% ethanol and 15% gasoline while most pump gas is 10% ethanol and 90% gasoline, Again, pure gasoline is not sold at many stations were reported t sell E85. These pumps are more common in the midwest. However; the numbers are growing and there is also some feel use across the country.
Ethanol has less energy than gasoline and E85 provides about 30% less power per gallon than regular gasoline. This results in reduced performance and economy. As newer vehicles are introduced, the difference in economy between E85 and E10 becomes less.
The test on 2008 chevrolet impala in the summer during an extended highway trip.
The mileage was calculated over 3 tanks of E10 both by the vehicle and using a calculator. The Vehicle averaged 32 MPG.
The vehicle was driven to near wmpty and filled with E85 twice. The miles per gallon dropped from 32 to 27. This represents about a 15% loss in economy.
E85 generally costs about 7% less than E10 when E10 is in the $2.00 per gallon range. However, as the price of gasoline increase, so does the price offset between E85 and gasoline.
Due to the corrosive nature of ethanol, some special components are needed. Magnesium,aluminum, or rubber may not be allowed to come in contact with high concentration of ethanol. The vehicle must be equipped with non-arcing fuel pump and spark arrestor in the filter neck. High flow injectors are needed because more fuel must be injected during cold engine operation.
Note: Some manufacturers use E85 compatible components across the board so improper use of E85 might not cause any damage to the system. On other vehicles such as honda, extensive damage will be done.
A spark arrester in the fuel filler neck is needed due to the danger of explosive vapors coming from the fuel tank during refueling. The alcohol in E85 will quickly turn to vapor if the vehicle is in the sun. The spark arrester also doubles as an anti siphon valve.
The Technology
E85 has ⅓ less energy than gasoline
Injecting the same amount results in lean mixture
Stoichiometric
Gasoline 14.7:1
E85 9.8:1
Max power burn for E85 is 7:1
Large injectors needed.
Since E85 contains about ⅓ less energy than gasoline, injecting the same amount as gasoline under a similar operating condition will result in an effective airfuel mixture that is lean.The stoichiometric ratio for gasolineIs 14.7:1 where as E85 requires a 9.8:1 mixture.
In order for engine to achieve a maximum power rich burn with E85, the mixture must be about 7:1. This will require higher flow fuel injectors than would normally be used with gasoline.