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Old 01-30-2012, 10:12 PM   #20 (permalink)
California98Civic
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Join Date: Mar 2011
Location: Coastal Southern California
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Black and Green - '98 Honda Civic DX Coupe
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90 day: 66.42 mpg (US)

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Old Mechanic and cfg83 suggest ways to mitigate higher emissions from a cool cat (pun intended). I like the idea of finding ways to mitigate the problem.

But how much of a problem is there? Does a CA smog check report fully correspond to what our cars are really doing on the road as far as emissions? The smog check is designed to measure what a car will emit when continuously running, right? But P&G and EOC mean the car is off quite a lot. So the test overestimates what actually comes from a hypermile car during an hour and a certain distance, no? The total emissions of our cars may be more than a normally driven identical car in some categories of pollutants, or it might be less, when the overall daily emissions are considered. We can't know for certain until we know a few other things about your driving. If our cars burn no gasoline 50% of the time because they are being driven through EOC, shouldn't we consider halving the numbers on our emissions reports to get a rough sense of what we might be emitting on our way to work?

Although the OP raises doubt, there are doubts about the doubts too. Seems like a perfect scenario for methodical investigation. We need test equipment and a test method.

One could test techniques and mods that attempt to mitigate or even improve overall emissions during a given commute using P&G and EOC and such. If overall emissions are less than a smog check indicates because P&G means the car is off at times, then couldn't an occasional mile or two of steady-state driving during your commute keep the cat warm enough that the overall emissions might be about the same or, who knows, maybe less than an ordinarily operating car? What mods would go along with technique (such as insulation for the cat)?

My car's cat is next to the block and attached to the exhaust manifold, so I imagine it gets hotter faster and stays that way longer, especially since I have completely blocked the grills. No cool air blows directly on the CAT. What else could I do to keep it warmer? Is overheating a possibility?

james
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See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.



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