Quote from tristancliffe :

With a bit more work you can show that exhaust gas temperatures cause further reactions, which often result in NOx, and these are much worse than plan NO2.

You mean CO2, don't you? Because NO2 = NOx.

Maybe

@ Tristan, I didn't know if it was directed at me, but as you point out, I'd already pointed out my own pig ignorance, so if you HAD been directing it at me, I'd pre-agreed with you anyway

If anyone has read Terry Pratchett's "Science of Discworld", it has some fairly well argued observations on us as a race with regard to our impact on the environment, and on a larger scale our impact on nature. It's worth a read, if for no other reason than for his humorous interjections, analogies and similies, but if you're an environmentalist it's probably gonna piss you off.

Quote from bal00 :

You mean CO2, don't you? Because NO2 = NOx.

NOx includes all of the oxides of nitrogen, some of which do have different deleterious effects than plain N02. Running leaner than stoichiometric creates dramatic (orders of magnitude) increases in NOx emissions.

Running lean does not dramatically increase CO2 emissions as far as I can remember.

Quickie

Quote from skiingman :

NOx includes all of the oxides of nitrogen, some of which do have different deleterious effects than plain N02. Running leaner than stoichiometric creates dramatic (orders of magnitude) increases in NOx emissions.

Running lean does not dramatically increase CO2 emissions as far as I can remember.

Running lean doesn't really affect CO2 emissions at all for the same power output. The air-fuel ratio does affect the composition of the cylinder-out gases (Tristan's graph is very good but his NOx peak is a little too far into the lean region) but by the time these gases reach the tailpipe any partially combusted material (either as hydrocarbons or CO) should have been oxidised (assuming the car has some sort of catalyst fitted) to CO2...net result is that CO2 scales with fuel input, regardless of whether it's rich or lean.
The only way to reduce CO2 emissions is to reduce the fuel consumption of the engine.

Quote from tristancliffe :

Quickie

I was actually looking for that graph to post. Nice work.

Quote from tristancliffe :

Aren't you meant to have left us in peace?

I'm going. Got till the end the end of the week . . .lol.

It's friday. Has he gone yet? Can we talk about him yet, or would it be safer to wait til Monday?