Chevy Colorado & GMC Canyon banner

1 - 17 of 17 Posts

·
Registered
Joined
·
388 Posts
Discussion Starter #1
Since many of us are not getting the mpg we thought we would
(i was and am attributing it to winter gas, 2-3 mpg drop)

and since ethanol gives less BTU that gasoline
and we can expect our mileage to be lower from now on due to increased ethanol usage

and since potentially compensating for this by increasing energy ie octane may help, at least in winter

I am going to switch to Higher octane (super) the next couple tanks to see if it compensates for the lesser mpg caused by ethanol

can't hurt and if it helps it justifies (more than) the increased cost by increasing mpg

anyone else? Orange Whip?
 

·
Registered
Joined
·
1,519 Posts
Or just move to Florida and have summer gas year round, lol. My truck is definately doing better here since coming here the end of december, getting around 20 mpg now, was getting 14 to 17 in R.I with the winter gas.
 

·
Registered
Joined
·
388 Posts
Discussion Starter #3
no fair Curt!

This is the first time i have seen this much drop
and there are no factors other than winter gas that would cause it ie no mods, different driving habits, etc
 

·
Registered
Joined
·
388 Posts
Discussion Starter #5
I figure that in normal conditions and usually burn regular or plus

But with ethanol cutting down btu, maybe running higher octane in the winter will help compensate by providing some additional power thus bringing up the energy level?

Gonna give it a try and see if any difference
 

·
Registered
Joined
·
3,901 Posts
I'm not an expert on the subject, but I don't think octane denotes energy level. It just shows how much it will resist detonation. I would think higher octane would be worse in the winter because it burns slower.
 

·
Registered
Joined
·
2,019 Posts
Our midgrade 89 comes with ethanol, so that's what I usually get. Along with the winter additives, and 600lbs of sandbags in the bed, I get 13 mph around town, and just did a road trip to Minot and back, 430 miles, got 20 mpg at 70mph.

I get the about the same with plain 87.
 

·
Registered
Joined
·
9,570 Posts
brakenit said:
I'm not an expert on the subject, but I don't think octane denotes energy level. It just shows how much it will resist detonation. I would think higher octane would be worse in the winter because it burns slower.

Higher octane gas actually contains LESS energy ( btu's per gallon ) than lower octane.

Enjoy: http://www.offroaders.com/tech/octane.htm
 

·
Registered
Joined
·
1,180 Posts
Our regular and mid grades here contain up to 10% ethanol and I found this winter that by switching to premiun with no ethanol I can get about 30-40Km more between fill ups then I was getting on Regular.
I don't think it has anything to do with the octane, I think it is just a result of the BTU difference between the two types of fuel.

I have noticed that on really cold days the truck smells like it is running very rich. There is a strong smell of gas(like some has been spilt in the garage) right after I start the truck and for the first little while until it heats up. If the temp drops again this winter I am going to take it to the dealership and get it checked but I was wondering if anyone else has noticed this as I would think this could really effect winter gas mileage.
 

·
Registered
Joined
·
9,570 Posts
Our trucks run REALLY rich at idle
 

·
Registered
Joined
·
1,895 Posts
rangerbob said:
Our trucks run REALLY rich at idle
I am sure you are right. I am guessing the rich low speed mixture is needed to keep the cats hot to keep the emissions clean.
I have heard lots of new '08 diesel truck (Ford and GM owners) are screaming mad about 8-10mpg fuel mileage in their new trucks. The low fuel mileage is apprently caused by strict emission standards. These trucks have several cats to keep visible smoke and soot from occurring. The diesels are set to run rich to keep the cats hot to burn off the pollution. You can recognize these new diesels with their GIANT exhaust tips.
 

·
Registered
Joined
·
1,180 Posts
upflying said:
rangerbob said:
Our trucks run REALLY rich at idle
I am sure you are right. I am guessing the rich low speed mixture is needed to keep the cats hot to keep the emissions clean.
I have heard lots of new '08 diesel truck (Ford and GM owners) are screaming mad about 8-10mpg fuel mileage in their new trucks. The low fuel mileage is apprently caused by strict emission standards. These trucks have several cats to keep visible smoke and soot from occurring. The diesels are set to run rich to keep the cats hot to burn off the pollution. You can recognize these new diesels with their GIANT exhaust tips.
This got me thinking about carb sync on a motorcycle.
On a I4 motorcycle(the ones I have the most experiance with) you usually have 4 carbs and they need to be in sync.
When you have a carb that is out of sync and running lean you have one exhaust head pipe that is very much hotter then the others.

Thus I would have thought that if they needed to keep the cats hot they would be more inclined to run the engine lean for heat rather than rich.

Also, if the exhaust smells that heavily of gas would that not indicate that a lot of fuel vapor is being alowed to pass through the system unburnt and I would think that would make it hard to pass an emmissions test in one of those places where they stick a sniffer up you exhaust pipe.
 

·
Registered
Joined
·
3,881 Posts
Weston said:
there are no factors other than winter gas that would cause it ie no mods, different driving habits, etc
Weather and warm up times are always a factor.
 

·
Registered
Joined
·
48 Posts
When i run the e10 91 octane fuel, my gas mileage absolutely blows. Maybe 13 at best, and thats on the highway
 

·
Registered
Joined
·
141 Posts
Same rich mixture noticed here on cold mornings....smells like raw gas. Even with the ethanol mixture in the winter, I've only noticed a 1 or 2 mpg drop on any of my other vehicles. Anyone have Hptuners to play with the mixture settings?
 

·
Registered
Joined
·
388 Posts
Discussion Starter #17
Found this from December article

"Supporters of biofuels have this week begun a drive to increase the percentage of ethanol used in conventional transport fuels.

According to a report in The New York Times, advocates of the biofuel said blends of 20 to 30 per cent of ethanol in conventional fuel, as opposed to the current 10 per cent blend, produce "better fuel economy than ordinary gasoline".

Supporters of ethanol claim to have discovered a "sweet spot" where fuel economy increased above that boasted by conventional fuel. This was unexpected because ethanol is around two-thirds less powerful as a fuel compared with gasoline.

During tests this summer, a Chevrolet Impala using new flex-fuel engine technology that allows it to run on fuel blends containing up to 85 per cent ethanol reportedly achieved 15 per cent more mileage when using a blend of fuel containing 20 per cent ethanol than it did when running on standard fuels.

A General Motors spokesman told The New York Times that engineers were unsure how a mix expected to contain less energy could produce better mileage, adding that more robust testing of the technology was needed.

However, despite the test, automotive specialists are sceptical about the environmental benefits of fuels containing more ethanol and have questioned their potential impact on engine durability.


re fuel smell - Cold mornings also cause the fuel mixture to be richer until
the vehicle gets to normal operating temperature and the computer can maximize efficiency. And it appears also since cold air is denser than warm it causes more air to be available in the same cubic space so the system adjusts by adding more fuel to the mixture.
So the trucks will run richer on a cold morn until optimal running
temp is reached
 
1 - 17 of 17 Posts
Top