Quote:
Originally Posted by Buzzcut
Jordo,
Point of fact, ethanol, because it is an oxygenate, should be cleaner burning and NOT leave a residue. Of course, the ECU knows just how much oxygen there is in the cylinder, and will richen the mixture in response. Maybe that's why you get that residue.
You are absolutely right that ethanol is a "bang". Gasolines there days are precision mixtures of various hydrocarbons, all of which burn at slightly different temperatures and pressures, engineered to smooth out the "bang" as much as possible. Putting ethanol in there in such a high concentration kind of defeats that.
With that said, neither has been an issue for me so far. I had absolutely no issues in 15,000 miles of splash mixing E85 in my Saab. We will see if the X5 does well with it.
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IMHO,
Octane booster in premium gas doesn't come solely from ethanol, it's more likely Toluene or Xylene (very high BTU when burned), when I auto-cross with a bunch of friends most kids dump 2-3 gallons of Xylene before their heat run which can be had at Home-depot for around $10/gallon but the octane is like 116 on this puppy, it's alternative to race gas.
Ethanol packs less BTU than gasoline for the same mass/vol density. that's why E85 will cost less but poor mileage. OK, water probbaly has high number of octane(resistance to detonation at high temp and presure) but zero BTU
This is the same analogy betwen propane and natural gas, all backup home power generator will produce less wattage when switched from propane to natural-gas it's no way around it.