Smog "hypothetical"

[DFXR]

You got that backwards. NOx happens from high combustion temperatures. Gasoline has 2 more carbon atoms and 12 more hydrogen atoms than ethanol, and about 1.5 times the amount of chemical energy than that of ethanol.

The reason you run it, is there are less carbon atoms to make CO, less Hydrogen and thus less unburnt hydrocarbons and a cooler reaction to reduce NOx emissions.

As for this test, I like to have it down around 3-4 gal gas per gal ethanol. Or if there is E85 in your vicinity, wait till you're almost empty and put a few gallons of that in the tank.

That's weird ... I ran a ratio like the one you describe (3 or 4:1) and got NOx numbers off the charts. Took it back with 10 gal gas / 1 gal DA and passed with normal NOx numbers.