e85 and ls1
I don't think our cars can run on 85% ethanol out of the box. The owners manual doesn't say anything about the ls1 being a FFV (Flexible Fuel Vehicle). The main thing is the fuel system components. Most are made from plastic or rubber and a higher concentration of ethanol will quickly dissolve or corrode such components. The other is FFV's have sensors is the fuel system that detect the level of ethanol and adjust F/A ratio and timming. Its not impossible to convert your system but it would be a royal PITA. I think e85's octaine rating is like 100-105. So to get the best performance out of it you would have to increase compression to almost drag only ratios. Otherwise your fuel economy will suffer.....baddly.
