Quote:
Originally Posted by dr249
So you think normal engines are running richer than stoich in order to protect the parts from over-temperature?...
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Yep, we do that, but only under high load because of the fuel economy hit. There are a number of engineering and manufacturing issues with water that make it unattractive on a mass-production car. Fuel doesn't freeze, the injection systems are already in place, most folks wouldn't like having another tank to fill every time they stop for gas, there'd be a significant cost hit...
One thing to remember is that the mixture isn't homogeneous, so even at stoich there are lean and rich zones in the burning charge - which means that in order to get every BTU out of the fuel you have to run
leaner than stoich. But if you do that then you get more NOx, and have no way to get rid of it in the exhaust stream because the converters need to have alternating rich/lean excursions in order to function.
Of course, if you manage to get the aluminum to burn it gets REALLY hot.
