Quote:
Originally Posted by Daox
I went to the EV club's build day this weekend and ended up bringing up this project with a friend there. I told him about the two limits that I might run into and that I thought it would probably be the dilution problem more than the pinging. He suggested something I hadn't thought of. Ethanol apparently is more combustible and able to be run leaner than gasoline. So, he suggested that if I run into this limit that I try increasing the ethanol content of the fuel to run a richer EGR mix. So, I now have an option should I find that I can dilute the mixture too much for gasoline (E10 in my area).
I am going to have to do more research on ethanol though. I really don't know much about it.
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In this case, I would imagine that the real difference is not combustibility so much as it is the oxygen that ethanol carries. Compared
against ethane, ethanol liberates about 11% less energy, but requires 14% less air (3.0 moles O2 per mole C2H5OH versus 3.5 moles O2 per mole C2H6). Comparing ethanol to other non-oxygenated hydrocarbon fuels will yield comparable results. If pumping losses are the big issue, then ethanol will improve performance. If not, the loss in energy will hit you. (I suspect that certain high performance engines prefer ethanol for this very reason... not only does the higher octane allow for higher compressions, ethanol also requires less air in an already air-limited WOT system.)