Flex Fuel Engines

flex fuel engine

Flex fuel engines have an injection system that can operate with gasoline, with any mixture ratio of gasoline and ethanol, or with pure ethanol. Which means they are capable of running on 100% petrol or 100% bio-ethanol or a combination of both. Regardless of the supply, customers are supple when it comes to the choice of fuel and are able to respond to possible price developments immediately. Clearly flexibility with the choice of fuel is the key argument for buying vehicles with flex fuel engines. The market share of such flex fuel engines are high while other markets still show great potential to establish those systems. The main advantages of Flex Fuel Engines for Your Vehicle is resource saving mobility with ethanol as fuel. Flex Fuel Strong Hybrid Electric Vehicles (FFSHEV) basically houses an electric motor which powers the vehicle alongside the traditional petrol engine.

Dual fuel vehicle means the engine that uses two fuels (gas and diesel) together. Bi Fuel means the engine could run on either fuel but separately. On the other hand FFV is capable of running on either petrol or ethanol or a combination of both. Hence it is a combination of Dual fuel vehicle and Bi fuel vehicle.

How do flex fuel engines work using ethanol?

A flex fuel car looks just like any other kind of car. The main differences between the two lie with the engine and fuel system. Flex-fuels vehicles can run on regular gas, various ethanol blends and other types of fuel . Production of ethanol is mainly by fermenting agricultural residues. The main ethanol blends on the market today are E85 and E95, which get their names from their compositions. E85 is 15 percent unleaded gas and up to 85 percent ethanol . While E95 typically used in diesel powered vehicles is up to 95 percent ethanol. An engine that runs on regular petrol can also run on flex fuel which means any car with the spark-ignition engine can run on this flex fuel .

Components that comprise the fueling system of flex fuel vehicles are also crafted to be ethanol compatible. Otherwise higher water content of ethanol could cause rust to form and damage the fuel system from the inside out. Despite these different components, maintenance costs for FFVs are generally the same as for other vehicles, and sometimes are even lower, since flex fuels burn fuel more cleanly .

Comparison of flex fuel Vs gasoline vehicles

Apart from few differences, a flex fuel engine and a gasoline car have almost similar components.

Flex Fuel Engine

  • Battery: The battery provides electricity to start the engine and power vehicle electronics/accessories.  
  • Electronic control module (ECM): The ECM controls the fuel mixture, ignition timing, and emissions system; monitors the operation of the vehicle; safeguards the engine from abuse; and detects and troubleshoots problems.    
  • Exhaust system: The exhaust system channels the exhaust gases from the engine out through the tailpipe. There is a 3 way catalyst to reduce engine-out emissions within the exhaust system. 
  • Fuel filler: A nozzle from a fuel dispenser attaches to the receptacle on the vehicle to fill the tank. 
  • Fuel injection system: This system introduces fuel into the engine’s combustion chambers for ignition.        
  • Fuel line: A metal tube or flexible hose (or a combination of these) transfers fuel from the tank to the engine’s fuel injection system.
  • Fuel pump: A pump that transfers fuel from the tank to the engine’s fuel injection system via the fuel line.        
  • Fuel tank (ethanol/gasoline blend): Stores fuel on board the vehicle to power the engine.            
  • Internal combustion engine (spark-ignited): Here fuel inject into either the intake manifold or the combustion chamber, where it is combined with air, and the air/fuel mixture is ignited by the spark from a spark plug.            
  • Transmission: Transfer mechanical power from the engine and/or electric traction motor to drive the wheels.          

  Gasoline Car

  • Battery: The battery provides electricity to start the engine and power vehicle electronics/accessories.
  • Electronic control module (ECM): The ECM controls the fuel mixture, ignition timing, and emissions system.Similarly it monitors the operation of the vehicle, safeguards the engine from abuse, detects and troubleshoots problems.            
  • Exhaust system: The exhaust system channels the exhaust gases from the engine out through the tailpipe. A three-way catalyst is there to reduce engine-out emissions within the exhaust system.            
  • Fuel filler: A nozzle from a fuel dispenser attaches to the receptacle on the vehicle to fill the tank.    
  • Fuel injection system: This system introduces fuel into the engine’s combustion chambers for ignition.            
  • Fuel line: A metal tube or flexible hose (or a combination
  • ) transfers fuel from the tank to the engine’s fuel injection system.            
  • Fuel pump: A pump that transfers fuel from the tank to the engine’s fuel injection system via the fuel line.            
  • Fuel tank (gasoline): This tank stores gasoline on board the vehicle until engine require it.            
  • Internal combustion engine (spark-ignited): In this configuration, fuel inject into either the intake manifold or the combustion chamber. Then it is combined with air, and the air/fuel mixture is ignited by the spark from a spark plug.            
  • Transmission: The transmission transfers mechanical power from the engine and/or electric traction motor to drive the wheels.            

The Mechanism Behind Flex-Fuel Vehicles    

The engine of a FFV is designed to run on more than one type of fuel .Usually gasoline or a combination of fuel is stored in the same tank . When you start the engine a sensor mounted in the fuel line can detect the percentage of fuel blend . The ethanol/methanol/gasoline ratio, or the fuel’s alcohol concentration and sends a signal to an electronic control module. The electronic control module then adjusts the engine’s fuel delivery control to compensate for the different fuel mixtures.The engine then delivers the precise amount of fuel into the engine via injectors. Rest, it works similar to a conventional engine.

In order to ascertain the exact proportion of gasoline and ethanol in the fuel tank the engine management parameters should set accordingly.The virtual sensor to helps in adjusting the fueling rate. Knowledge of the ratio between the two fuels is necessary because of the different parameters of the various fuels . Nowadays, physical alcohol sensors have become more common, especially in markets with challenging emissions and on-board diagnostics requirements.

During a re filling time the sensors check the fuel tank level sensor. This helps get an approximate value for the volume of fuel . Thereby use an algorithm to allow the EMS to calculate two approximate new values of the stochiometric Air Fuel Ratio( AFR ). And then it check that the fuel added was either gasoline or a combination. On restarting it monitors the O2 sensors and looks for a perturbation in their signal. Once when the AFR is swinging in the rich or lean direction it adjusts the operating parameters gradually until it locks on to the new value and the vehicle has been ‘conditioned’. Figure shows a representation of a sensor detection system. The initial swings to the new AFR is quite rapid, but an extended period of conditioning is necessary .

Since flex fuel engines are increasingly popular they are not a miracle solution. The good news is they enable us to consume fewer fossil fuel as plant-based bio ethanol is a renewable energy source. It also burns much more cleanly, which is great for the entire environment. But flex fuels get fewer miles than gasoline-powered vehicles. Also they can be pricier and there aren’t many gas stations selling E85. Higher blending of ethanol results in higher manufacturing costs which translates to pricier vehicles. Some engine parts especially those that come in contact should be replaced with a compatible product to avoid corrosion. Despite all these ,automotive companies say that they are ready to move with government regulations on ethanol blending of E20 by 2025. Government officials have said that many popular car making companies have agreed to make flex fuel engines in coming future.