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Iso-stoichiometric ternary blends - in which three-component blends of gasoline, ethanol and methanol are configured to the same stoichiometric air-fuel ratio as an equivalent binary ethanol-gasoline blend - can function as invisible "drop-in" fuels suitable for the existing E85/gasoline flex-fuel vehicle fleet. This has been demonstrated for the two principal means of detecting alcohol content in such vehicles, which are considered to be a virtual, or software-based, sensor, and a physical sensor in the fuel line. Furthermore when using such fuels the tailpipe CO₂ emissions are essentially identical to those found when the vehicle is operated on E85. Because of the fact that methanol can be made from a wider range of feed stocks than ethanol and at a cheaper price, these blends then provide opportunities to improve energy security, to reduce greenhouse gas emissions and to produce a fuel blend which could potentially be cheaper on a cost-per-unit-energy basis than gasoline or diesel.

A study was conducted to investigate the relative influence of charge cooling and autoignition chemistry on the greater knock resistance seen by alcohol fuels compared to petrols when operating under “Beyond RON” conditions in a Port Fuel Injection (PFI) engine. The methodology employed was that of a modelling study calibrated and validated using experimental data, with ethanol and iso-octane used as representatives of the alcohol fuels and petrols respectively. A two zone combustion model combined with an empirical knock model formed the centre of the modelling work, with the experimental investigation conducted on a boosted PFI engine. The comparison of knock resistance between ethanol and iso-octane showed that autoignition chemistry plays the largest role in the knock resistance advantage of ethanol. This dominance by autoignition chemistry is partly aided by PFI's poor use of the charge cooling capacity of ethanol.