andrewr, answers inserted in red.
Would you care to elaborate on that?
I did already, you just failed to copy and paste the rest of the answer.
Formation of CO2 releases more than 3x the energy of CO.
OK, and by running richer and richer you generate a lot more CO. This was graphed way back before computers…I have the graph. I can't easily print the graph I know to be accurate but this one is probably near enough
My high school chemistry calculations (admittedly with 25+ years of rust)
Don't worry….I am worse off 
suggest that 10% excess fuel reduces the energy (heat) released by about 3%.
Not really, it slows down the burn rate, and the peak pressure occurs later, therefore at a lower peak pressure. Just like your air compressor, compress to a lower pressure you don't get the heads as hot. And no fuel used at al.
You get more molecules and hence more pressure at the same temperature, or the same pressure at a lower temperature.
