CARBOB energy content.

[omgwtfbyobbq]

Apparently, CA uses a different oxygenate blend than the rest of the nation uses, as well as cutting everything with 6% ethanol. Does anyone happen to know what the difference in energy content between CARBOB and BOB is? I'm curious because I stumbled on something The Toecutter posted.

Wrong. It was pretty shabby. Because, driven just as hard, Nevada through Utah, then on to Denver, fuel consumption suddenly shot down, to 43 MPGs. Just peetering around Denver, for a week, visiting people I know, I saw fuel consumption numbers, on the Prius, I've never seen, in California. Urban driving, I saw numbers in the readout, over 12 miles per gallon higher, than anything I've ever experienced, in California. Driving this car, exactly the same as I do, in California, the Prius was averaged 12 miles to the gallon better, in urban Denver, than it does, in urban Los Angeles.

~ Long drive, 13 hours and 40 minutes home, exactly same thing: Denver, through Utah, corner of Arizona, to Nevada, the Prius got over 43 miles to the gallon. Last fuel stop, topping off in Baker, California, heading westbound, to Los Angeles, driving this thing just as hard as ever, fuel consumption inexplicably crumbed, to 36 MPGs. Some reason, mere act of purchasing gasoline formulated, for California, cost 5 MPGs.

[bones33]

I've noticed similar effects with CA gas. My old mazda truck always ran stronger and got better FE with non-CA gas. Motorcycle all of a sudden was running really rich when I moved back to WA. Whatever oxygenates they use cause carbureted engines to run a little leaner, that's why motorcycle manufacturers have different carb specs for california models. I definitely noticed that CA gas produced less power, requiring more fuel to go the same distance.
Sorry, no help on the particulars but I seem to remember more benzene.

[mrmad]

Wow, I guess that means the 47.4mpg on my last tank is really 52.4mpg? That would put me in the top ten, wohoo!

While there certainly could be a difference in mileage between CA gas and 49 state gas, the post Toecutter made on his Prius indicated he was getting much better mileage in Denver. I wonder if this could have something to do with the altitude and how the ECU in the Prius handles the difference in pressure? If the gas was the same, you'd almost think the car would get worse mileage at high altitude, but who knows?

I'll try to do some research on this, but I do know that CA changes gas formula from winter to summer. It'd be interesting to know the difference between these two types as well.

[Hockey4mnhs]

When do they change from summer gas to winter gas. is there a spicific month or is it temp related

[zpiloto]

I thought that the energy content would be the same as any other E10 blend and that the main difference was that in CA they were using a low sulfur content gas. Also didn't all gas to low sulfur this year along with diesel?

[Bill in Houston]

Originally Posted by Hockey4mnhs

When do they change from summer gas to winter gas. is there a spicific month or is it temp related

Specific month.

It would seem to me that being at high altitude would increase your gas mileage. Less wind resistance, lower pumping losses, etc...

And for the OP, I cannot think of any reason for CA gas to have a much lower energy content. No reason at all. The gas in Denver should have been an oxygenated winter blend, so it's not even a conventional vs rfg thing...

[cfg83]

Hello -

There was a fellow here by the name of koinos :

Hi, another Paseo from Long Beach CA
http://www.gassavers.org/showpost.ph...00&postcount=1

... As I am working at the refinery as an engineer I have practical knowledge and experience about fuels ...

He only posted a few times, so maybe he is gone. But if he is lurking, then I'll bet he would know.

CarloSW2

[VetteOwner]

Originally Posted by Bill in Houston

Specific month.

It would seem to me that being at high altitude would increase your gas mileage. Less wind resistance, lower pumping losses, etc...

And for the OP, I cannot think of any reason for CA gas to have a much lower energy content. No reason at all. The gas in Denver should have been an oxygenated winter blend, so it's not even a conventional vs rfg thing...

dont forget about less power. My family and i took a vaction to colorado in elevations of 7000+ feet above sealevel while we live in a measily 600 feet above sealevel. our van (96 Aerostar)seemed to be a noticeable difference(huge one might say) in power. so it may not get better MPG because you will have to press the pedal harder to get the same force out...i would think.

[ELF]

California banned mtbe starting 1/1/04 as a oxygenate, now they use ethanol, supposed to be 5.7%. but can be from 4% to 9% depending on the fuel supplier.
zpiloto is right they recently switched to low sulfer, but I think there is more to it than that.
Carbob has limits on lots other chemicals like benzene, xylene,Toluene,Ethyl Benzene,Nhexane,cyclohexane to name a few. adding more or less of some of these could change how much energy the fuel has.
I'm not sure the oxygenated gas is doing what its supposed to do though.
Carbob will be changing the max. oxy % on 7/1/07, the max oxy content is going from 0.25 to 0.009

[MetroMPG]

Originally Posted by VetteOwner

dont forget about less power. so it may not get better MPG because you will have to press the pedal harder to get the same force out...i would think.

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).