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Gas Mileage
Posted: Tue Dec 05, 2006 9:56 am
by cheshirecat
The gas mileage in the soob has taken a piss poor turn. I'm about to fill up and I've gone 200 miles with average->occasionally hard driving. Any ideas on why this might have occured? I can think of a few possibilities but let me know what you guys think....
Posted: Tue Dec 05, 2006 10:36 am
by complacent
Oxygenated Gasoline... It sucks the big one here,
every winter
Posted: Tue Dec 05, 2006 10:52 am
by cheshirecat
explain
Posted: Tue Dec 05, 2006 11:05 am
by Mr Kleen
there is a different gas blend during the winter months. they add oxygen to help with emissions, but it just ends up diluting the gas and you burn more.
the google will have more info if everybody else is as lazy as I am...
Posted: Tue Dec 05, 2006 11:07 am
by complacent
here
and
here
and
here
and
here
Basically, they "water down" the gasoline in the wintertime, using O2 to do it. The "reduced emissions" comes at a MPG hit. The regulatory groups involved claim a "1 to 3 %" reduction in mileage... IRL it is much worse than that.
Re: Gas Mileage
Posted: Tue Dec 05, 2006 12:07 pm
by sirwilliam
cheshirecat wrote:The gas mileage in the soob has taken a piss poor turn. I'm about to fill up and I've gone 200 miles with average->occasionally hard driving. Any ideas on why this might have occured? I can think of a few possibilities but let me know what you guys think....
Aside from the "Winter Gas", have you tweaked the tune on your car recently?
Posted: Tue Dec 05, 2006 12:15 pm
by Sabre
Yep, Oxygenated gasoline sucks, esp. with turbo cars. One other thing to think about is that the colder air expands a good bit more in your engine, so you have to use a little bit more fuel to keep your AFR's. Depends on how your car is setup though wether it will compensate like that.
Posted: Tue Dec 05, 2006 12:29 pm
by sirwilliam
Sabre wrote:Yep, Oxygenated gasoline sucks, esp. with turbo cars. One other thing to think about is that the colder air expands a good bit more in your engine, so you have to use a little bit more fuel to keep your AFR's. Depends on how your car is setup though wether it will compensate like that.
23 degress at 5AM and my boost cut on me
do not like that at all. Never did that on my other tunes
Posted: Tue Dec 05, 2006 3:01 pm
by Libra Monkee
Is there any fuel additive that can be used to offset the amount of suckage caused by the ethanol?
Posted: Tue Dec 05, 2006 3:03 pm
by Sabre
Will: Yep, time to turn down that boost! I'm guessing you wpiked bad b/c of the cold air.
Chuck: Not sure!
Posted: Tue Dec 05, 2006 3:23 pm
by Libra Monkee
Crap, time to get the chemistry set. Once methanol bonds to ethanol they cancel each other out, right?
Posted: Tue Dec 05, 2006 3:51 pm
by Mr Kleen
octane booster?
Posted: Tue Dec 05, 2006 4:31 pm
by Cereb Daithi
i think that there really are times i do sort of enjoy not having a turbo
Posted: Tue Dec 05, 2006 4:40 pm
by Mr Kleen
more power, more problems
Posted: Tue Dec 05, 2006 5:13 pm
by Sabre
Mr Kleen wrote:more power, more problems
lol, ain't that the truth!!!!!!
Posted: Wed Dec 06, 2006 10:29 am
by cheshirecat
or just more money....
Posted: Wed Dec 06, 2006 10:23 pm
by zaxrex
The crux of the problem comes out to energy density and stoich point of your fuel.
Both methanol and ethanol have lower specific energies (but higher octane ratings). That means that you have to add more fuel to get the car to see 14:1 because the alcohols run about 10:1 stoich and has less energy than regular gas.
If you have the ability to tune your car, you can run fuel leaner due to the knock resistance of the alcohol aditive, but that will increase the operating temp of the engine. In the cold weather, that won't be a problem because the radiator will be working at higher efficiency and you will probably have the heater on.
Posted: Thu Dec 07, 2006 7:35 am
by sirwilliam
zaxrex wrote:
If you have the ability to tune your car, you can run fuel leaner due to the knock resistance of the alcohol aditive, but that will increase the operating temp of the engine. In the cold weather, that won't be a problem because the radiator will be working at higher efficiency and you will probably have the heater on.
"Uh, honey...looks like I am going to have to upgrade to a FMIC and upgrade my radiator to keep up w/ the new gasoline."
Posted: Thu Dec 07, 2006 7:57 am
by chicken n waffles
Posted: Thu Dec 07, 2006 8:51 am
by Mr Kleen
see, they
WANT to be driven hard!
Posted: Thu Dec 07, 2006 9:37 am
by chicken n waffles
subaru wants me to die, apparently.
well, if i gotta go, it might as well be with the only girl i know who isn't a whiny, blood-sucking demon.
Posted: Thu Dec 07, 2006 9:47 am
by Mr Kleen
chicken n waffles wrote:well, if i gotta go, it might as well be with the only girl i know who isn't a whiny, blood-sucking demon.
QFT
Re: Gas Mileage
Posted: Thu Dec 07, 2006 1:19 pm
by avriette
cheshirecat wrote:The gas mileage in the soob has taken a piss poor turn. I'm about to fill up and I've gone 200 miles with average->occasionally hard driving. Any ideas on why this might have occured? I can think of a few possibilities but let me know what you guys think....
bad o2 sensors, clogged cat, leaks in various manifolds and piping, dirty or deformed spark plugs, clogged fuel filter, clogged air filter... that's probably too drastic for it to be alignment, but subtle alignment changes can also affect mileage. are your tires properly inflated?
Is the car otherwise acting normally? No new sounds or smells? No misses? I notice it's gotten really cold in the last couple days, pretty quickly. How long has it been doing this?
We typically are close to empty at 260. The light comes on around 220-240, and we know we've got another 30 miles or so to go before the car quits.
