Quote:
Originally Posted by Number_Cruncher
Most people talk about colder air being denser, and hence being more efficient. However, our engines are power limited by the fuel pump settings - they are still running with a large excess of air when they begin to smoke.
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OK, let me try. The reason colder inlet air is more efficient has nothing to do with the amount of O2 available for combustion. You have to think of an internal combustion engine as a thermodynamic air cycle, all the fuel does is provide the energy to heat (and expand) the air. The maximum efficiency is obtained by having the maximum density difference between the cold inlet air (that must be compressed) and the heated air that provides the pressure during the power stroke. The net energy generated by the engine is really just the difference between the energy obtained by the power stroke and the energy required to compress the air. That is why inter-coolers provide higher efficiency on turbo-charged engines. End of Thermodynamics 101 class.
