Quote:
Originally Posted by CT335xi
Although there are cons to running ethanol based fuels as they dry up seals and rubber components due to its alcohol content , the one thing it doesn’t do is rob you of power. Ethanol runs cooler , higher octane, and less resistant to knock which anyone running a turbo or boosted vehicle wants. As far as power it’s more then a 10 whp difference from 91 to 93. I would think on our n63tu engines with tune running 17-18 psi it’s more like 20 whp at least. I’ll take the 94 with 10% ethanol all day, wish we could get that in the states, and if I had e85 near by I would run that in my evo don’t know how the 50i would like it though but I’m sure 3-4 gallons of e85 would work nice with 91 or 93.
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Yeah, you are right. If you want serious power, and maximum the power gain, then higher octane is definitely the way to go.
But as you have mentioned above, Ethanol is a highly corrosive chemical that can eat through a lot of things along the fuel delivery system. While it is true that BMW sold in North America will take fuels with up to 10 percent Ethanol, but who knows if we are really getting no more than 10%. I prefer to be safe than sorry so I am sticking with No Ethanol fuel. Also ethanol has less energy content than gasoline, and I have detailed fuel mileage records from my past 3 cars and see at least 1 MPG better fuel economy with ethanol free gas. Last reason, for my daily drive, I do hope the tune can put slightly less stress on my stock drivetrain, just for inner tranquility.