How much E-85 you using Brad??? My statement was based on gasoline.

Some info on E-85:

http://www.experiencefestival.com/a/...nol/id/1345236

The following table shows the range of air fuel ratios typically used for burning gasoline, E85, and pure ethanol (E100) under an assortment of assumed operating conditions:

Fuel AFRst FARst Equivalence Lambda
---- ----- ----- Ratio -----
================================================== =======================
Gasoline stoich [14.7] 0.068 1 1
Gasoline Max power rich [12.5] 0.08 1.176 0.8503
Gasoline Max power lean 13.23 0.0755 1.111 0.900
================================================== =======================
E85 stoich [9.765] 0.10235 1 1
E85 Max power rich [6.975] 0.1434 1.40 0.7143
E85 Max power lean 8.4687 0.118 1.153 0.8673
================================================== =======================
E100 stoich [9.0078] 0.111 1 1
E100 Max power rich [6.429] 0.155 1.4 0.714
E100 Max power lean 7.8 0.128 1.15 0.870
=======================--================================================

The term AFRst refers to the Air Fuel Ratio under stoichiometric, or ideal air fuel ratio mixture conditions. (See stoichiometry.) FARst refers to the Fuel Air Ratio under stoichiometric conditions, and is simply the reciprocal of AFRst.
Equivalence Ratio is the ratio of actual Fuel Air Ratio to Stoichiometric Fuel Air Ratio; it provides an intuitive way to express richer mixtures. Lambda is the ratio of actual Air Fuel Ratio to Stoichiometric Air Fuel Ratio; it provides an intuitive way to express leaness conditions (i.e., less fuel, less rich) mixtures of fuel and air.
Air Fuel Ratio is always computed on the basis of ratios of mass (not volume). The following is a computation of the theoretical E100 (100% ethanol, C2H6O) Air Fuel Ratio, based on stoichiometric (perfect combustion) principles:
C2H6O + 3 O2 = 2 CO2 + 3 H2O
Adding up the molar mass for ethanol: (6 x 1.00794) + (2 x 12.0107) + (1 x 15.9994) = 46.0684 grams/mol of Ethanol
1 mol x 46.0684 g/mol Ethanol : 3 mol x 2 x 15.9994 g/mol Oxygen
46.0684 : 95.9964 = 1:2.0838 for the fuelxygen ratio for perfect (i.e., stoichiometric) combustion.
Now, oxygen is 20.9% of air by volume, or equivalently, 23.133% of air by mass, assuming that atmospheric gases behave as ideal gases. (See Earth's atmosphere.)
Hence, the theoretical air fuel ratio for E100 (100% ethanol) is:
(2.0838/0.23133) : 1 = 9.0078 : 1
So, for E85 (summer blend), the required air fuel ratio can be estimated as:
0.85 x 9.0078 + 0.15 x 14.64 = 9.8526
Likewise, for E85 (winter blend), the required air fuel ratio can be estimated as:
0.70 x 9.0078 + 0.30 x 14.64 = 10.6975, which is closer to the gasoline air fuel ratio.
The estimated required E85 summer blend air fuel ratio compares very closely to the value of 9.765 given in the table. In practice, though, the exact stoichiometric air fuel ratio for gasoline varies as a function of the exact blend of gasoline, which, in turn, is varied by time of year by refineries to increase or decrease volatility, prevent vapor locking, etc., for better matching seasonal climatic changes.
Deviations from stoichiometric combustion computed values are required during non-standard operating conditions such as heavy load, or cold weather operation, in which case the mixture ratio can range from 10:1 to 18:1 for burning 100% gasoline. Slightly wider ranges than even this on the low end of the air fuel ratio, dropping to below 8:1, are required for burning all possible blends of E85 and gasoline efficiently under all conditions of engine loads and inlet air temperatures.
At inlet air temperatures below 15 C (59 F), it is likewise not possible to start the typical internal combustion engine on pure ethanol (E100); for cold engine starts, starting the engine on gasoline and then transitioning to E100 can be done. Similarly, for starting a vehicle on E85 summer blend in extremely cold weather, it is likewise required to add additional gasoline during at least the starting of the engine, before transitioning to burning the E85 summer blend. In practice, it is easier simply to add more pure gasoline to the fuel tank when extremely cold weather is expected, prior to the arrival of the cold weather, to avoid cold engine start difficulties.
Fortunately for those converting non-FFVs to operate on E85, the wide range of inherent air fuel control required for burning pure gasoline is very nearly the same range required for burning many blends of E85 with gasoline up to approximately 60% E85, at least for non-extreme engine loads and non-extreme weather conditions. Hence, the common success seen in practice for burning many blends of E85 with gasoline even in non-FFVs at blends in excess of 50% E85, especially under light engine loads cruising under benign weather conditions.
All of these theoretical stoichiometric combustion estimated values should be taken only as approximations to what may really be required for achieving perfect combustion. The lambda sensor is what ultimately confirms whether stoichiometric combustion is taking place in practice.
Additionally, the ideal "stoich" (common shorthand way to indicate stoichiometric) mixture typically burns too hot for any situation other than light load cruise. This is the target mixture that the ECU attempts to achieve in closed-loop fueling to get the best possible emissions and fuel mileage at light load cruise conditions. This mixture typically can give approximately 95% of the engine's best power, provided the fuel has sufficient octane to prevent damaging detonation (i.e., knock).
The "Max Power Rich" condition is the richest air fuel mixture (more fuel than best power) that gives both good drivability and power levels, within approximately 1% of the absolute best power on that fuel.
The "Max Power Lean" condition is the leanest air fuel mixture (less fuel than best power) that gives good drivability, acceptable exhaust gas temperatures to prevent engine damage, and power levels within approximately 1% of the absolute best power on that fuel.

Tom V.
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