What are the mechanical differnces between a flex-fuel vehicle and a regular one?

Larger fuel filter. Fuel injection computer programmed to allow for greater flow rates so as to account for ethanol's low energy density (normal fuel injection computers are programmed to stop increasing flow rate at 35% ethanol).

All cars since the 80's are required by law to have fuel paths hardened against ethanol and most fuel injectors are capable of the flow rates needed to burn 100% ethanol, this was to avoid the damage caused by gasohol (up to E15) in the 70's, note they also renamed gasohol of up to E10 as "premium unleaded" in the 80's. The fuel pump probably doesn't need to be changed.

Most conversion kits involves a unit that goes between the fuel injection computer and the fuel injectors which triples the flow rate signal from the computer, since the computer works on feedback from the knock and oxygen sensors, it will think it's adjusting the fuel rate for ethanol content between 0% and 35% when in reality it's adjusting it for ethanol contents between 0% and 100% but in greater increments. It's advisable to replace the fuel filter after the first tank of E85 as the ethanol will loosen residues that had settled out of the gasoline over the years when it ran on gasoline. Unless the fuel pump doesn't have the capacity to pump enough fuel (like the injectors, most do) the pumps don't need to be changed. You may also want to paint the gas cap yellow and apply a flex fuel label.

Depending on the model of the car, the conversion kit may include replacement fuel injectors. I'm not aware of any kits that include a replacement fuel pump.

There's only one conversion kit that has completed the lengthy and difficult EPA certification.

Larger fuel injectors and all the rubber in the fuel system must be replaced. Ethanol is corrosive and would destroy the stock fuel system.

E85 is a waste of money. It costs almost as much as gas and gets you 2/3 the mileage. If you took out the government subsidies it would actually cost more than gas. It also take more energy to make than you get out of it.

Nata - E85 cars can run regular gas just fine. It just doesn't work the other way around.

if you do not replace all the seals and carbon steel parts in your fuel system, the ethanol will leak and cause a fire. Cars can handle 10% ethanol, at 15%, your are in serious trouble.

If you switch with a kit, you can then only run E85, if you can't find a E85 station, then you will be stranded. The cars sold as E85 from the factory can run anything from 0% ethanol to 85% as they have sensors that measure the ethanol content.

More power from E85, absolutely not UNLESS you change out the pistons and maybe the heads. If some one says they have more power, its because they advanced the timing, not from the E85.

Finally, E85 cost more than plain ol gasoline, why would you spend money that will make you buy more expensive fuel???

As John mentioned above, the site is change2e85.com They are very helpful if you call them too. Best of luck.

I had a 2006 ford crown victoria that was flex fuel and it seemed to perform better and had more power on E85 than on gasoline.

Nata, E85 here is 1.89/gallon. Gasoline is 2.65/gal And regardless of the pennies difference between the two I support US farmers, not foreign sheiks.

Most of the cars made after the 80's are already flex-fuel.

To check if yours is go to the following list:

http://www.agua-luna.com/ffc_sheet.html