Team from GM, Ford, FCA reviews how to calculate engine efficiency benefits of high octane fuels

Green Car Congress

The preflame reactions are a strong function of temperature, so evaporative cooling from the fuel can also play a significant role, which is particularly important for fuels containing alcohol. Knock and fuel octane rating are becoming increasingly important due to many powertrain design trends including downsizing, downspeeding, cylinder deactivation, and hybridization. … Alcohol and gasoline-alcohol blends also offer efficiency benefits independent of their octane value.

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