Quote:
Originally Posted by Ecky
Best I understand, you're running a 30:1 AFR under boost, so it isn't like you're reducing vacuum. I would guess that the extra gasses in the cylinder are acting as a medium of expansion, and are causing some thermal efficiency gains as well. Water injection can increase economy because of the expansion from the phase change, which more than offsets the energy lost to the phase change itself, just as an example. And, if you have twice as much air in a cylinder, and you add a given amount of energy to it (combusting a fixed amount of fuel) the temperature will be lower and you'll be losing less energy through the cylinder walls and combustion chamber. The turbocharger also harvests some of the expansion energy and puts it back to useful work.
Just an educated guess, however.
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Upper class and graduate courses expand on these concepts. You are but a hop, skip and jump from a doctorates.
We also must add that pgfpro has certain advantages built into his engine system. His head design as well as the turbocharger produces increased turbulence and adds heat to the combustion mixture. The reaction rate ( increased thermo-chemical reaction rate ) is reflected in his need to only add 4 degrees ignition timing. In our attempts to run ultra lean mixtures with a Daihatsu engine with hemispherical combustion chambers, we found we had to add over 15 degrees additional timing to reach our torque potential.
I am not sure if his 4 degrees of timing included the NOs injection?
The bottom line is that . . . increased heat, increased turbulence and increased thermochemical activity result in increased flame speed.
Compressing the air/fuel mixture increases the heat.
A high swirl/tumble head design increases turbulence as well as the force of a turbocharged system.
The addition of oxygen, ozone or hydrogen allows for increased thermochemistry to occur.
In the run-up to the AutoXprize, a team proposed to run an engine on pure oxygen and gasoline. This was an extreme proposal that would need ceramic materials and water injection. The longevity of the ceramic materials was questionable and the amount of water needed was considerable to carry about. Outside of how to produce and carry the pure oxygen the idea was sound in that the ignition initiation could be carried out just before top-dead-center (TDC). I do not recall their expected target for BSFC (brake-specific-fuel-consumption).
Using the nitrogen in our surrounding air as a working fluid is much more plausible if we can keep combustion temperatures below 2300 degrees Centigrade or if reactions occur quickly enough to prevent the formation of NOx pollutants.