The higher the altitude, the lower the required octane.I will run any octane of ethanol-free gas before I'll put 10% ethanol blend in. QT stations around here mostly all have the 87 octane ethanol-free for $2.95 and I get - you guessed it - 10% better mileage when I'm running 100% gasoline. I have not noticed any difference in power going from lower to higher octane. I don't think our engines have enough compression to really need higher octane gas. When I was in Durango Colorado a couple of years ago, I was running 85 octane gas the whole time and got great performance out of it in the 8500-11000 foot elevations.
On our engines you will probably not ever hear ping because the knock detection system is working. If the engine is knocking slightly (incipient knock, not readily audible), the system is sensitive enough to detect it and will retard the ignition timing, which reduces performance and raises the exhaust temp. So you might benefit slightly form higher Octane fuel even if you can't easily sense the difference in performance or fuel economy. The worst-case for engine knock is hot and dry ambient and high baro.If the engine pings on 87, then a higher octane fuel may give better performance. However, if this is an OE engine, then there is something wrong with it. If the compression has been increased or the timing artificially advanced, then the engine may need higher octane to take advantage of the modification.
You can expect 3% better fuel mileage with Ethanol free because it has 3% more energy per gallonI haven't tried ethanol free gas since my last Civic... Which also got 10% better mileage when burning ethanol free. It became unavailable at the pumps in my area for several years, when it came back it was only 87 and I was in cars requiring 91+. I haven't been brave enough to try 87 puregas in a vehicle requiring 91 yet but I may soon now that the seed has been planted.
You can expect exactly 10% better gas mileage because there is exactly 10% more GAS in your tank. The alcohol doesn't do a damned thing to help the car go forward.You can expect 3% better fuel mileage with Ethanol free because it has 3% more energy per gallon
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Sounds like your car just doesn't run very well on E10. Ethanol works perfectly well as a fuel by itself, as long as the engine is tuned for it.You can expect exactly 10% better gas mileage because there is exactly 10% more GAS in your tank. The alcohol doesn't do a damned thing to help the car go forward....
Yes, alcohol burns and you get a tiny amount of energy from it.
Well, good question. Not everyone has gasoline readily available, or at least not at a reasonable price. Gasoline has to be made from petroleum, but anyone can make ethanol. If you lived in a land that had no oil and was under embargo, then ethanol might look pretty good.I wonder why I would bother tuning a car to run alcohol when I have gasoline readily available?