I guess I thought upgrading the fuel system would be obvious. Stock lines can handle it. But the injectors and pump will need upgraded because they don't flow enough. I don't forsee anything else being an issue either. Yes ethanol may attract water and is corrosive to some materials. But I have switched over my 1992 Turbo Eclipse to E85 only. Walbro 255 and FIC 1250cc injectors. Stock lines, stock fuel filter, everything else. I've ran 20k miles with E85 and never once changed the tune after I started running it. The fuel filters have came out squeaky clean after the first fuel filter change. Car has sat for 6 months since it's gotten cold, fired it up about a week ago for the first time since then and it still runs great, even the with 6 month old water attracted E85. 3rd-4th gear pulls WOT and no knock even. I would not be scared to run it in a V with the flex fuel sensor and the ECM programmed for it. I would really like to do it to mine soon considering there's an E85 station less than a mile from my work place.

 

I'm using a MegasquirtII/Extra ECU, and that's one of the options. I can switch back and forth between differant fuel and ignition maps with just a toggle switch.

If you need different tunes for E85 and E10, why wouldn't you need a different tune for e30 or e60? That 20-50% increase in ethanol is going to be a reduction in BTU's, and an increase in octane. You would need to be adding more fuel to compensate for the alcohol content.

I don't know how the GN guys do it. I don't know much about those cars - except that they're cool.

I'v heard about it attracting water, but have not experienced it. It seems to me that the fuel system is sealed to control fume escape - part of the smog stuff. So if it's sealed, how does a significant amount of water get in there while sitting? IDK if that's a big issue or not? And why doesn't that happen at the gas station before you buy it?

I'v left some in a sealed plastic fuel container for a few months in the summer, and then tested it. It did not have a measurable amount of water in it. I have some in a container that's been sitting in the trailer since October. Maybe I'll test that and see if it has water in it.

While I was building mine, I considered adding the flex sensor. With my ECU it would be fairly simple. But there were a few things that pushed me away from that.
- They're kind of expensive, and seem to have a high failure rate. You can buy kits on e-bay to replace the sensor with a resistor, and fool the computer into thinking it's there and working. A work around instead of repeatedly replacing the sensor.
- The lines were too small. Which you could work around using a couple of Y blocks.
- I didn't see a reliable method for converting the nipples to AN fittings.

So I just wait for the tank to be nearly empty before I switch over. That seems to work well.

And we keep hearing from AAA and car makers that the new e15 will void the warrenty and kill the car. And yet people are running e85 simply by increasing the injector size. So is e15 a big deal or not? IDK.