NOX is always increased if combustion temperature goes up. CO decreases generally in the same situation. Chucking hot exhaust gas back into the engine will increase it's operating temperature, thereby putting NOx even higher.
Any anyway, what about the green thing. Somewhere in the world factories and chucking out dirty fumes as a result of the fabrication and manufacturing process.
All we're doing is moving the source of emissions really. I think cats were a step too far, too soon. Back in the early 1980's Honda had some very successful prototypes of the CVCC engines. These ran on incredibly lean fuel/air mixtures. Sadly, legislation trashed two decade's worth of investment and research by making the cat virtually mandatory for petrol cars.
That's the reason that diesels now generally flatten petrols with similar sized engines in performance terms (and they do, without question).
The legislation was also a step not far enough because at that time diesels were truly horrid, noisy, slow things that belched soot and all sorts of other crap from the exhaust. |