Fuelly Forums - CARBOB energy content.

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Depending on temperature difference rolling resistance may increase or decrease, and aerodynamic drag would decrease because of lower pressure/density. Pumping losses shouldn't change as long as the percentage of oxygen per other stuff (Nitrogen, etc) doesn't change since the only drop is in pressure, not oxygen content iirc. I'll PM that chem engineer, and keep on looking online.

edited due to idiocy. ;)

Found a CA gov website that claims CA gasoline has 111,500 Btu per gallon. 0nl1nec0nv3r510n dor c0m says U.S gasoline has ~124,900 Btu per gallon. Which is 12% difference in energy content! :o

Edit- yup

Quote:

Originally Posted by EIA

1 gallon of gasoline = 124000 Btu

Quote:

Originally Posted by CA gov

A gallon of gasoline in California contains approximately 111,500 Btu

Not only do we have to pay ~30-40 cents more per gallon, we get about 10% less energy! Which translates to about 60-70 cents more per 124000 Btu.

Quote:

Originally Posted by omgwtfbyobbq (Post 44969)

Found a CA gov website that claims CA gasoline has 111,500 Btu per gallon. 0nl1nec0nv3r510n dor c0m says U.S gasoline has ~124,900 Btu per gallon. Which is 12% difference in energy content! :o

EPA website list RFG with ethonal blended fuels at 111,836 so CA not that far off then the rest of the country that has winter blend it just that CA runs it year around right?

Quote:

Originally Posted by MetroMPG (Post 44943)

That would theoretically also improve FE due to reduced throttle (pumping) losses Bill was referring to (assuming you didn't also use lower gears more).

Generally speaking, cars driven at higher altitudes should get better mileage than cars at lower altitudes (all else being equal).

well it is a van (ranger truck frame. engine, and most likely the same trasmission) it is an automatic + mountains = shifting around a bit when goin up hills/mountains but down the hills/mountains we just put it in either 3rd or 2nd and let the engine do the brakeing.

Quote:

Originally Posted by zpiloto (Post 44971)

EPA website list RFG with ethonal blended fuels at 111,836 so CA not that far off then the rest of the country that has winter blend it just that CA runs it year around right?

I don't think it's the winter blend since that only varies 1.7% per gallon (Avg energy content per gallon, summer versus winter) for most of the US, but the RFG like you mentioned. It's widely used in CA, but on a county by county, not state basis. It seems like if a driver lives in one of the blue areas they use it.
https://www.epa.gov/otaq/rfg/images/rfgmap.gif
Winter RFGs/summer RFGs show a respective 3% and 1% drop in relative energy compared to the same conventional gasoline. However, one thing that's still not covered is the difference between CA and federal oxygenated blend... For instance, in CA if 10% (the label on the gas pump states up to this figure) ethanol were used, the energy content would drop by 3.4%. This is required by law in order to get the oxygen content at around 2%, iirc the AQMD is supposed to have the Oxygen at .2% in a few months, so I still have no clue as to what the difference between CA RFG, other RFG, and conventional gasoline is... Talk about a PITA. :confused:

I applaud your research, I spent about 1/2 hour on the weekend and the best I could find was a description of the many chemicals that were banned and what they are replacing them with. Reminded me of how much I hated organic chemistry.

Quote:

Originally Posted by omgwtfbyobbq (Post 45054)

I just gave up. What I find interesting is the large swing in the allowable BTU for gasoline that alone can make a difference. From the EPA site:

Energy Content (btu per gallon)

Minimum Maximum Difference

Summer 113,000 117,000 3.4%

Winter 108,500 114,000 4.8%

How many stations get the maximum allowed you think?:rolleyes:
Any way good luck on your quest?

Heh, yeah... if there's ~4% difference between stations, who knows? I just think that anecdotal blurb may be onto something... May just be a lark. I'll keep on looking in a bit, I should configure a comp for my uncle. mrmad, thank god ochem wasn't a requirement for me. ;)

Well, the last spike in mileage must have been caused by switching away from the winter blend, since according to this, we switch back to regular CARB gas in March

Quote:

10/1 - 2/291.8% to 2.2% Approved SIP

Course, that's only a .5mpg difference for me, so I'm wondering where the other ~2mpgs came from? Probably the drop in average speed, or it could be the AFM mod? Too bad I can't use this gas tank for a comparison, ~15 minutes of idling at 1000rpm and ~10 minutes of reving to 3000rpm in N should shave at least 10% off of my mileage figures. Shows me for leavin' my truck's parking lights on! :D

Quote:

California RFG
California implemented Phase II of their RFG program a number of years ago. There are some differences between the California RFG program (referred to as California Cleaner Burning Gasoline or CBG) and the federal program. We frequently receive questions on this topic since details on the differences were not covered in the manual.
The California CBG program is required statewide. The State of California uses their own computer model for compliance. This model, called the “California Predictive Model,” is similar to the federal complex model but does not incorporate evaporative emissions. California’s CBG program attempts to achieve greater emissions reductions than the federal program by placing more stringent requirements on certain gasoline parameters. The California specifications place maximums on aromatic content (22%), olefin content (4%), and sulfur content (30 ppm). In addition the maximum distillation temperature for T50 and T90 are lowered.