Engine variant for E85 fuel: Theory

E85 is a mixture of 15% petrol and 85% ethanol. Ethanol has the formula C2H5OH and accordingly differs from petrol as it is one substance and not a mixture of several.

E85 has the following properties that distinguish it from pure petrol:

• Lambda 1 at 9.8:1 instead of 14.7:1.
• Worse evaporation at low temperature.
• Higher octane rating (104 RON).
• Faster combustion.
• Colder exhaust due to greater fuel mass at Lambda 1.
• Better fuel-air mixture cooling during evaporation.
• More aggressive against certain metals and plastic/rubber.