FFV vehicle and regular Gasoline vehicle

FFV(Flexible Fuel Vehicle) is some times called multiple fuel vehicle is also an IC engine and this is designed to operate on gasoline, E10, E85 and mixture of E85 and gasoline. The main part of FFV is Electronic Control Unit (ECU) that enables to use various fuels with proper management inside using software and electronic sensors. In FFV there is mechanism of detecting the ethanol and gasoline ratio and make appropriate adjustment to engine ignition timings and air fuel ratio that accounts for ethanol and optimize performance and emission control. All processes are done automatically according to the actual blending detected by the sensors. However FFV does not need cold start ancillary system. Some modification needed such as some rubber, plastic, magnesium and aluminum which are used to make gas tank, pump, and tubes for distributing oils and injector nozzle needs replaced with other materials or may be corrosion resistant. The width of the injector nozzle has to be expanded to meet higher circulation of fuel and valve, the piston, piston ring and spark plug has to be modified.
Pure ethanol is different than conventional gasoline in the sense that it has the constant boiling point temperature, higher octane rating, lower energy density and needs more heat for vaporization. If we consider the blend of E85 fuels by volume then this blend now have higher octane, low energy density than the regular gasoline and this contains only 69-74% of energy of regular gasoline. Hence this shows that this needs 35% more fuel and fuel handling infrastructure (fuel tanks and delivery) than the original gasoline engine to enable the same level of mobility (total vehicles miles of travel).with stoichiometric air fuel ratio of 10( it is almost 15 for gasoline),E85 needs more fuels per pound per air for optimum combustion.
Operating priciple of FFV:The operating principle is some how different than the using bioethanol as fules. These engines are operating on compression ignition principles (CI engine).All most all diesel engine runs happily with biodiesel if the biodiesel is of high quality and pure. New diesel engine does not need any engine modification when there are running up to 20% blending (B20) blending and the biodiesel is pure (as per ASTM). However engine needs the following modification when to run with biodiesel.
Rubber Seals: Rubber used for seal should be replaced with non rubber products such as VITONTM because biodiesel reacts with rubber
Cold Start: Problems for cold starting when high blends biodiesel are used and the concentration is more .This is overcome by the adding fuel heating system or using biodegradable additives reduces viscosity of the biodiesel.
Oil Change: Frequent oil changes are necessary when operating biodiesel. This depends on the type of the bio diesel used on the engine.
Engine Timing: Higher blends engine performance will improve when 2-3 degree changing on the engine timing for 100% blend. Use of advance injection timing and increase in injection timings are necessary for reducing NOx emission.