Lowering NOx

[Jay Negrin <jmnegrin@domain.elided>]

Raymond asked about lowering oxides of nitrogen emissions.

Whoo boy, what a task.  They tried that with low-tech solutions in the early
70s here in the states.  You are trying to lower the combustion temperature,
thereby cutting down on oxides of nitrogen (which makes up nearly 80 percent
of the air we, and our cars, breathe. 

The typical strategies used were:
Decrease the compression ratio
Decrease the spark lead (advance)
Increase the exhaust gas percentage being recirculated to the intake.

ALL of these ideas have, as a side effect to lowering combustion temperatures,
lowered specific horsepower and torque output.  This is just what we want,
right??!!  Not quite, please. 

Running the air/fuel ratio a bit lean will increase the combustion
temperatures, which is what we are trying NOT to do, so we wqant it to run a
little on the rich side, to cool things down in the motor.  The catalytic
converter, at least in older cars, like mine, only oxidize the unburned
hydrocarbons, and perhaps some of the carbon monoxide.

Oxides of nitrogen are difficult to deal with, especially in a simplistic manner.

I wish you luck in your endeavor.

Jay Negrin
76 Alfetta GT (still has a cat, here in southern California)

------------------------------