Quote:
Originally Posted by Ecky
How lean, exactly, I wonder? Honda's lean burn motors run well at 22.5-24.0:1.
Are they going to need exotic emission controls?
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The toughest standard is something like 0.02g/mile NOx (need to check on that again), which works out to something in the tens of ppm depending on how much fuel you burn in a mile.
I think if you drop the combustion temperature by a little bit it is easy to go below 100ppm (which should be able to squeak by the minimum standards on a smaller engine car). HCCI supposedly should be able to control the burn speed so that maximum temperature is lower.
I am not sure exactly how this works, but my hunch is that they use a lot of hot EGR to control the charge temperature (to induce autoignition) and reduce the burn temperature, and somehow avoid knock.