Fuel economy variatons with different fuels

[LowRyter]

On 2/5/2022 at 2:25 PM, LowRyter said:

I got gas at BucEe's and the MPG Tracker on my Corvette lost about 4 mpg and never caught up to the previous readings despite costing a dime+ more a gallon.  Then the stores are so big you have to walk two blocks from the gas pumps to the bathroom.  And TMI, usually when I stop, I need to go.  BTW- the crap sold there, whether consumable or not, ain't cheap, and it ain't special.  

Just another instance where Texans think they invented the first gas station, or BBQ, beer, kolaches, tacos, football or any other common place thing or idea.  Just making it bigger and expensive or putting a star on it doesn't make it better or even as good.

I could tell ya what I really think but I think I'll keep tactful about it.   

Well, it a happened again.  Got some 91 at Casey's for the Ducati.  Mileage went from 42 down to 38.   Just filled it with Phillips 66, within 10 miles I was back to 42.5.

How do they put filler in gas?  Is it the same volume but less weight? Air? 

 

[Pressureangle]

I haven't been able to turn up any science on gasoline formulation that gives any clues, but I can assure you that you are not insane. I regularly see + or - 5mpg on my Sport, and on my recent 3k mile trip on this BMW GSA, + or - 3mpg. These are consistent across an entire tank of gas, and I've been very careful on both to ensure my usage was similar enough not to affect it. The BMW needed a good tune and one stick coil (2 plugs per cylinder) has a hot fail, so that may explain the lesser difference since efficiency is down overall. 

Meh.

[LowRyter]

@Pressureangle

Don't purchase Buc-ee's or Casey's gas.  

[docc]

New topic from split posts for further, ongoing discussion . . .

 

[80CX100]

I don't pay close attention to such things,but from a trusted source;

With his chainsaw,he gets 15-20% less cutting time from a full gas tank of premium with ethanol,compared to pure,alcohol free,premium gas.

fwiw ymmv

 

[Pressureangle]

Ethanol content; no clear data. However, Ethanol takes x3 the liquid volume per horsepower than 'gasoline'. So if you have 10% ethanol content, that instantly removes 3% of your horsepower; that then is also dependent on your engine- if it's carbureted, it can't adjust for the ethanol's additional oxygen requirement, and the engine runs lean, reducing power. This is the chainsaw scenario. On an EFI engine with oxygen sensors, the fuel system can increase the amount of liquid mixed in to maintain power, but then increases volume consumption. Either way, it sucks. But it doesn't explain the huge difference in mileage in the same vehicle of either type, with the same usage, using what is expected to be similar 'mandated' pump fuels. 

We're being skinned, simple as.

[GuzziMoto]

Another aspect of Ethanol in gasoline is that while different pumps may dispense gasoline with Ethanol in it the percentage of Ethanol may vary considerably. In theory, it should contain no more then 10% Ethanol unless it is labeled E15, which can contain up to 15% Ethanol. But often gasoline contains less then the max Ethanol content. The less it contains, the better your fuel mileage tends to be.

Funny enough, the other side to it is an engine can make more power burning gasoline with Ethanol in it if it is tuned to do so. Ethanol has less power for a given amount then gasoline does. But Ethanol contains oxygen, so more Ethanol can be burned then gasoline, offsetting the reduced power density. Fuel mileage will decline even further, but if you want power it is an easy way to make more. Sadly, most V11 engines don't adjust their fueling on their own (no O2 sensor), and they certainly don't adjust their fueling based on Ethanol content of the fuel. Flex fuel vehicles tend to do that, the tech is out there. But that is beyond Moto Guzzi and the V11. You could likely tune a V11 to run on higher Ethanol content fuel, but given the fuel tank has issues with E10 I am not sure it would be a good idea.

[LowRyter]

Casey advertized 100% gasoline 91 octane.   The difference was nearly 4 mpg

[80CX100]

On 11/13/2023 at 6:10 PM, LowRyter said:

Well, it a happened again.  Got some 91 at Casey's for the Ducati.  Mileage went from 42 down to 38.   Just filled it with Phillips 66, within 10 miles I was back to 42.5.

How do they put filler in gas?  Is it the same volume but less weight? Air? 

 

Iirc,I read recently on this forum or another one idk?

Apparently fuel distributors sell the primo higher quality gas from the top 1/2 or 2/3 of the huge gasoline storage tanks,to the big,brand name fuel companies.

The bottom 1/2 or 1/3 is sold to the discount gas chain outlets;logically,it will contain more sediment & water.

If storage tank maintenance or management is sub par,that fuel at the discount gas station might contain a lot more water & sediment.

HHhhhmmm

[80CX100]

9 hours ago, Pressureangle said:

We're being skinned, simple as.

[LowRyter]

I usually buy cheap gas for the car.  Many times ethanol.  For the bikes I'm a little more careful.  Usually 100% gas / 91.  

I've only seen precipitous mileage drop on these two occasions.  91 in the Corvette from Buc-ees and 91 in Duc from Casey's. 

Anymore, I just run 87 in the Corvette, makes no difference how it runs. 

 

[ScuRoo]

That ethanol helps those fossil fuel resources last a little longer …

Ya think? 

[Pressureangle]

I worked at a friend's Texaco station in the mid-80s. He was scrupulous about quality in everything, starting with the bathrooms. His friend owned an independent station halfway through town ("Woody's Gas" lol). One time we couldn't get gas from any regular channel, so my friend went to Woody for enough low-grade to get by. Woody said, "@#$$#!, I would rather see you turn them away than let them catch you selling what I do". Heh. Yes, there's a difference. And they're very careful never to let you know all the secrets.

[80CX100]

7 hours ago, Pressureangle said:

And they're very careful never to let you know all the secrets.

There are many bottomless rabbit holes you can go down;anything to do with energy,are always huge ones. 

History is nothing more,than lies agreed upon. 

Question  Everything  Friends 

 

[LowRyter]

23 hours ago, 80CX100 said:

Iirc,I read recently on this forum or another one idk?

Apparently fuel distributors sell the primo higher quality gas from the top 1/2 or 2/3 of the huge gasoline storage tanks,to the big,brand name fuel companies.

The bottom 1/2 or 1/3 is sold to the discount gas chain outlets;logically,it will contain more sediment & water.

If storage tank maintenance or management is sub par,that fuel at the discount gas station might contain a lot more water & sediment.

HHhhhmmm

Casey's is brand new station, less than year old.  And Buc-ee's is the latest in "super stations", bigger than cable!