I'm pretty sure cold air is heavier than warm air, and will have more total content of all gases, o2 included. Have you heard of thermal lows in the weather? That means warm air is lighter and therefore the pressure is less. Cold air is heavier and will compact more, causing more air molecules per cubic in. Thats why cold air intake improves power, as well as some affect of advanced timing, I would guess.

I think your idea of the winds maybe a factor, but it'* not that strong all the way down the state that would account for the a 10% difference, at least I don't think, but it certainly is possible.

As far as oxygenation, I read that it will affect gas mileage by as much as 10%. Especially SO Ca is one of the worst in the country because of Los Angeles, and the gas is among the most expensive as well because of the "special reformulation".

http://www.chevron.com/prodserv/fuel...etin/motorgas/

This is a link I found pertaining to oxygenated fuels. Check the question and answer section for some interesting reads on current topics.

Good find. I read on the fuel economy page that for Ca gas they believe it to have a 3% reduction in fuel economy, but some individual drivers have reported from 10 to 20% reduction. They write it off as anecdotal, because they claim most drivers don't keep careful records. I can certainly see that as a possiblity, and in my case that is true, but I preceived a fairly significant drop in mileage when I moved from San Jose to San Diego. I haven't found proof yet, but it seems like * Ca. gas is weaker than N Ca. gas. I wonder if that is published anywhere.

I would also guess that even though the gas itself has a 3% reduction in heat value, depending on how the PCM was programmed, it may perceive a greater reduction and overcompensate for the weaker fuel. Maybe later models take this into consideration, but models made before oxygenation became a standard don't know how to efficiently compensate for this oxygenated fuel. That'* the way it looks to me. Is there an aftermarket chip out there made to compensate for this? I'd buy one if there was.

Here'* the section I read on fuel economy. The California part of it is especially revealing.

http://www.chevron.com/prodserv/fuel...p#fuel_economy

Hey guys, I just got my internet turned back on..signal dropped to near 0 for some odd reason..anyway

Time is short again so here'* a little bit...

This is JMO and totally up for debate..."not the D word!" haha

GreenMachine - Too much to comment on line by line but a few points to consider...
Hot air has less 'content' and the MAF (and o2) will pick up the difference and the computer will compensate by using less fuel. I've heard of 2-3gr/sec per 10deg difference. So a CAI with a 80deg intake vs. pulling 140deg hot air could make a difference of 120-180gr/sec which will make an impact on fuel usage..not entirely sure how minute though.

K&N - I think the vast majority of 'improvement' in MPG seen switching filters it just because they put a new one in. I think the only way to really check the difference is to use a brand new cheap-o filter vs. a brand new K&N. But then again some of that will be because of lower parasitic losses (?!?).

On oxygenation...The "official" statement is "no more than 3%" loss in mpg but I've been reading as much as 3-5mpg. Of course the government will use a PERFECT running little engine and an extremely light foot in their tests. Also it will depend on how much oxygen is added.

"Federal Clean Air Act - requires gasoline to have a year-round average of 2% by weight of oxygen in ozone non-attainment areas categorized as "extreme" and "severe" (e.g., Sacramento, eastern Los Angeles, Riverside, San Bernardino counties). The CAA also requires an oxygenated fuel that contains 2.7% oxygen by weight in areas categorized as non-attainment for carbon monoxide (only a concern in Los Angeles). "

The government always paints the brightest picture when they impose something on us. I suspect the 3-5mpg is more reality. I think San Diego and Los Angeles are treated pretty much the same, because we sometimes get L.A. air floating down here and vice versa, depending on the weather patterns. It sucks, but that'* the price of cleaner air, and it is working. I've noticed significantly less smoggy days in the last few years.

I've typed a little something out about the filter dilly in another thread. Debate shift! haha

http://www.bonnevilleclub.com/forum/...ic.php?t=24211

Up for thoughts on this one

Yeah, another "no dur" way to look at this is by thinking about how hot-air balloons float UP ...or why cold water sinks...yiddi yada

You guys are gonna make me wish I had paid attention in science and chemistry. Is the density of the air contributed to the oxygen content or the speed of the molecules in it?

haha thats ok, I just guess right a lot

Both actually, when something heats up the 'little bits' speed up and move apart. When they cool they slow down and bunch together. Using this to your advantage - Pump gas late at night when its cold

the tanks are at least 5 feet under concrete, I dont think they warm up much. Otherwise everyone would pump at night.