Quote:
Originally Posted by RustyLugNut
... Modern computer controlled engines are far easier to tune for lean burn if you have a programmable electronic control suite. PfgPro and others have done it. If you can improve the combustion so that even extended lean burn does not result in increased COV ( co-efficient of variability ) you will not have the increased CO and HC output and thus will not need the help of the three way catalyst to meet emissions as NOx is very small...
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I have toyed with the idea of a second ECU that I might chip or otherwise hack, then swap out for SMOG testing. But I always have too many projects, so I wait. Still, it seems a 17.5:1 is a pretty modest lean burn and ought to be accomplishable on a car like mine, without a knock sensor, harmlessly. Would be fun to see what FE numbers would result in my aeromodded 98 DX with its tall '93 VX/CX transmission.
Quote:
Originally Posted by RustyLugNut
... Continued research in catalysts is resulting in materials that operate in lower temperature regimes. A close coupled CAT ( tucked right up against the engine head output ) utilizing lower temperature catalysts will allow lean burn operation again.
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Are there publically available research papers on such catalyst materials? I would be interested in attempting a read but I have failed to idetify good search terms or something.
Much of the time I would think I could minimize the somewhat cooled CAT problem at the end of a long LB cruise by going into neutral and coasting with the engine on for maybe 10 or 15 or more. The catalyst would warm up quickly but without the heavy load on it at the same time.