[JLMounce]

Really depends on the power you're trying to make. A good starting point is to look at your power potential, then up-size your fuel system by 30% to accommodate the added fuel requirements.

What's the engine build look like? E85 itself has less btu that gasoline, so simply using it in an engine that could otherwise be fed gasoline doesn't typically have much advantage to it. Where you start to see an advantage in power production is when the engine's compression ratios are raised to take advantage of the better cooling properties of ethenol as well as it's higher knock tolerance.

If you're engine is coming in like a typical street build with aluminum heads in the 10 to 10.5:1 range or an iron head in the 9 to 9.5:1 range, you may want to simply consider premium pump fuel. That's really kind of outside of your question though, but something to consider nonetheless.

What I would recommend is a stainless steel tank designed for EFI ready operation with internal baffling and sump. You also want an E85 compatible fuel pump. Walbro makes a 400lph unit that when matched with e85, should supply enough fuel for about 700 hp at the tire. Because this is ethanol I would recommend a PTFE hose or stainless steel hard line. Stay away from mild steel, aluminum or aluminized steel hard lines. The problem with ethanol is it's pretty hydroscopic compared to gasoline, so it absorbs water from the air around it which then rots your fuel system. At power levels up to about 650hp to the tire, a -6an line size for both the feed and the return should be enough. Getting close to that or above and you're going to want a -8an line on the car.

If this car isn't going to be driven regularly, e85 is probably not the best option because of its hydroscopic nature. That's when you really see issues crop up, especially if the car is going to be sitting for a month at a time with a half full tank and why you specifically want stainless steel here.

The other consideration here is fuel quality at the pump. While it's called e85, the governmental standard is a minimum of 79% of the standard for denatured ethanol in the fuel. That means that when you fill up at the pump, you could be pumping as low as E67 or even higher than E85. My research indicates that most areas that have plentiful supply and demand will have fairly consistent ethanol percentages between 70% to 85% depending on the season. You'll see e70 in the winter and e85 in the summer and depending on demand will have some of that mixing together during periods where the mix is changing seasonally. You may wish to go test several fuel stations before making this switch to see how much actual ethanol content is in the fuel.

The obvious issue here is tuning. There are three basic items that can be done for tuning here. The most convenient, but most difficult to setup initially is to run an EFI system along with an ethanol sensor that is able to make changes on the fly based on what's going through the sensor. Another option is to tune for a specific ethanol content and purchase that fuel from a supplier like VP that guarantees an accurate blend. The third option is to test the fuel each time you fill up and manually adjust the tune as necessary based on the quality of fuel you're pumping. Finally you can tune the car conservatively, meaning you tune it for a somewhat higher ethanol content mix and don't worry too terribly much if you get a tank that has more gasoline in the mix. You'll end up running a bit fat in this circumstance when the ethanol content is lower, but on some EFI systems like a Sniper or FiTech, it's really the only way to do it where you don't have to purchase and store fuel yourself.