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How much ethanol you can run depends on how much oversize the injectors are and how hard you drive. It takes 43% greater volume of E-85 compared to E-0. The computer with the oxygen sensors will extend the injection pulses to keep the mixture correct. If you don't drive hard the injectors will keep up and won't run lean. If you demand full power from the engine and the injectors can't supply enough fuel, the engine will run lean and probably ping. Knock sensors should retard the timing to protect the pistons, but too much pinging can melt piston tops. And that retarded timing will significantly affect performance and fuel economy. E-85 has a higher octane rating, so it can run leaner without knocking than straight unleaded, something like 110 compared to 87. A characteristic of an engine running lean is increased exhaust temperature. If I was going to run E-85 in an engine not factory rated for E-85 (and a lot of the rating is likely to be special EPA testing of the parts and the vehicle) I would add an exhaust gas temperature gauge and when that started to shoot up when working the engine hard, I'd back off on the throttle to cool it down. I've read several reports of non E-85 engines running fine on a 50/50 blend of E-85 and E-10. There are those that say any more ethanol than E-10 will do damage and with some engines under some conditions that may be true, but then those vehicles must stay out of Minnesota because in a year or so all Minnesota gas will be E-20. All Minnsota gas (though not labeled on most pumps) is now E-10. Back about 2000 there was a college contest to convert a vehicle to E-85. The process and results from U T Austin were on the internet. They changed the injectors, they changed fuel system gaskets, the fuel pump, and added a flash suppressor to the gas tank, they did not change or chip the computer, and they added graphics to the sides of the truck. For years Ford Taurus were available with a flex fuel option at no added cost, so the changes much not have been significant. As far as I can learn, EPA and CARB are strongly against conversions on the basis that they expect fuel system seals and gaskets to fail after several years of E-85 and those drips and leaks they consider will contribute excessive volatile organic compound pollution even though the engine exhaust will be cleaner. Gerald J.
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