California emissions and tall transmissions
 

So, IIRC, the California smog test runs the car at a handful of different speeds measured in mph, not rpm, and tracks emissions. If my car runs at lower RPMs at those speeds due to 20% taller gearing, will it also show lower emissions?

Makes sense lower RPM slightly higher load should produce at least lower volume of emissions. Not sure about percentage content which is how the gas hogs get away with their volume.

regards
Mech

My experience: http://ecomodder.com/forum/showthrea...since-126.html

Still well within spec.

The numbers vary so much from year to year, even when no other changes have been made.

Another suggestion: pump up the tires if your test is on a dyno. :)

Thanks for this, Metro and Old Mech. Looks like the gearing will have little relevance, which is fine. Last time I barely passed on one category (I forget which), but I have replaced the O2 Sensor as the tech recommended (it was original from 1998, I think).

Taller gearing increases the load on the engine, thus emissions tend to suffer. But if you could go 20%, that might be enough to force the transmission into a lower gear, which should help. Besides, 20% less cruise RPM doesn't necessarily mean more MPG anyway. Try it if you wish.