Gas mileage gone WAY down

[warsw]

I couldn't stand it any longer. I just have to through in my .02.

I have ridden in temps ranging from 16 deg F to 110 deg F and altitudes from sea level to 12K ft. I check my mileage every time I fill up and I have never seen any significant difference in mileage that I could contribute to either one. I see more of a change in mileage from raising and lowering my windshield.

I do know that, in my cage, I can see a big difference when they change to winter grade gas. The motor will run rough, have less power and get less MPG. I suspect this is what most are seeing with their bikes in the winter.

 

[Mississippi]

Sorry - have to type message before hitting enter key

 

[HaulinAshe]

Gawd, I should be a politician. Look how much debate I started!



Excluding all the aforementioned math, this is my formula:

%RoastedNuts = LEO Density x AmbientTemp / %Ethanol x AvailableVacationDays

When the LEOs and the temps are high, the Ethanol and VacDays are low, therefore I have to ride slow and get my nuts roasted way more.

Now in theory and due to my personal observations, fuel mileage tracks with %RoastedNuts.

 

[Mississippi]

Well, after much deliberation - and several adult beverages - I find that I may have been over analyzing the cause for reduced winter fuel mileage. The true cause is the basic human need to increase body fat during the cold winter months, very similiar to a bear. Here's the documentation:

https://www.usatoday.com/money/industries/e...ty_x.htm?csp=34

The math on this one is simple - as we all know, if you are carrying around a lot of stuff in your trunk of your car, your gas mileage will suffer because of the extra horsepower required to accelerate this increased mass and the formula for that is........... Oops, sorry - started to get technical again.....better have another beverage..........Aahh, OK, that was damn good, now, where was I, oh yea...the math:

Normal Weight + Extra Junk-in-the-Trunk=Reduced Gas Mileage

Pure and Simple

Can't believe it took us all day to figure that one out.

 

[ejworthen]

I don't think turbines are the same as internal combustion in this case. Density is adjusted for the O2 sensor and changes mixture. I think it's a very small x, but can't find the math. I think the fuel composition is the big X in the equation.

Well I think you're wrong. Anything that burns fuel would be effected in the same way. Whether it be a turbine, internal combustion engine, etc. I tried to find more info but have been unable to locate anything as of yet.

They only statement I can find on the internet is that in cold weather gas mileage can be reduced by as much as 50%. That would indicate to me cold weather is more of a factor than fuel composition. They do not indicate what factors of cold weather contribute to the reduction in mileage other than the engine not reaching operating temperature. They do state that an engines efficiency is reduced in cold weather.

How about a source my friend?

I meant to say mixture and not density there. I don't think turbines have O2 sensors and adjust mixture with a feedback loop.

Gasoline has 125,000 BTU's per gallon and ethanol has 84,400. Gasoline that is amended with 10% ethanol like done in some regions during the winter months will get 3.3% less mileage. Source

I would agree that the colder air will be more dense and require more gasoline, but it will also have a similar increase in the energy the charge has....which seems to me would offset it more or less. I still think temperature difference is a smaller factor than this, but look forward to any math or documentation supporting it.

If anything the colder air's density would increase wind resistance and that one would not be gained back, but I think it would be a fairly small variable unless cruising around at FJR nominal speeds.

I wish I could find a definitive source but have not as of yet. I’ve found some obscure references but they don’t apply to internal combustion engines. Thus I don’t think they are good reference materiel.

Gas turbines have a much more sophisticated means of monitoring combustion. Flame intensity and temperature of each combustion chamber are measured along with exhaust temperatures at various points. They also monitor oxygen, NOX, and opacity. It still maintains a set optimal fuel/air mixture. A motorcycle does the same thing. Just because it has a FI system doesn’t mean it changes that fuel/air ratio. It just helps it maintain the proper mixture more precisely. As air density changes it adjusts fuel flow to match air flow.

It would also seem to me a turbine would be better suited to measure the effects of air density on fuel consumption. The particular turbine I’m referencing is indoors and maintains a pretty consistent ambient air temperature. The only thing that changes is the air inlet temperature. It’s not affected by things such as tire pressure, air resistance, lubricating oil temperature, or fuel blends. Since it uses natural gas the BTU content of its fuel is pretty consistent unlike a motorcycle. The fuel is also heated before use to a consistent temperature year round so even that is a constant.

In my experience a turbine uses significantly more fuel at 30 F than it would at 60 F at the same load with all other variables being equal. This would indicate to me that air density has much more to do with fuel consumption than expected. This seems counterintuitive to me but that’s just how it is. I would think with an increase in air density you would also get an increase in efficiency but that is simply not the case. The increase in fuel consumption is greater than the increase in efficiency.

Combustion is still combustion no matter how you look at it. Whether it takes place in a turbine, gasoline engine, or diesel engine. It all works on the same basic principals.

I have yet to find a good reference or any math to back this up. I’m not so sure it will be available in reference to an internal combustion engine. It's out there somewhere, I just need to find it. I'm going to ask a couple of engineers at work if they can provide me some reference.

I do know the EPA is proposing new test methods for fuel economy window stickers. One of the changes is measuring cold temperature operation. There are some factors listed but I’m not sure what all the cold temperature measurements entail. I’d be curious if inlet air temp will be factored in.

 

[Grumpy]

Gee, I don't know about you guys, but when it gets colder I raise the winshield higher. I believe that this is likely Jeff's major contributor to lower gas mileage?

Jim

 

[warsw]

Gee, I don't know about you guys, but when it gets colder I raise the winshield higher. I believe that this is likely Jeff's major contributor to lower gas mileage?Jim

This is going to sound really strange but, last summer I was going across the desert, about a 120mi stretch. I was totally bored, not a turn in site. I started playing with my windshield and watching my MPG meter. I was shocked to see that as I raised my shield my mileage actually went up. I tried it over and over and it was the same every time. I even tried locking the throttle while raising the windshield and it was still the same.

All I could figure was that the shield was cutting the wind, when up, better than my body was when the shield was down. I tried to hide behind the shield when the shield was down and then I would get the same results as when the shield was up. Go figure.

Has anyone else found themselves so bored that they have tried this? Did you see the same or was I just hallucinating.

 

[PMC FJRider]

Over the summer I put a calsci windshield on, & noticed a drop in milage. I didn't think anything of it because I was driving a LITTLE faster than before. Because of the heat, I cut about 4"off the stock windsheild & put that one back on. After doing that, my milage went back up (from 48 to 41, back up to 48mpg). I thought it would get worse with the shield being shorter, because of more wind drag from me.....but I guess not. The calsci windsield is back on because my early morning commutes have been in the 20's in a few spots up here. And as expected, my milage went back down to around 41/42mpg.

DK

 

[madmike2]

Perhaps the BTU rating of gasohol is only 3% less, but once I leave the "Golden State" and the metropolitan area of Reno, my gas mileage jumps from 38-40 mpg to 48+ mpg. That's considerably more than 3% difference. Even riding twisty roads from Moscow a couple of years ago I was getting in the 46-47 mpg range. A drop from 46+ mpg to 40 mpg is more in the 15% range.

The above differences were on the '04 with a "AMAHAY" windshield, but I've noticed similar results on the '05 with a CeeBaileys +4+3.

Anyone else who travels into different states with "real" gasoline rather than gasohol notice as drastic a change?

 

[HaulinAshe]

Gee, I don't know about you guys, but when it gets colder I raise the winshield higher. I believe that this is likely Jeff's major contributor to lower gas mileage?Jim

Sorry Grumpy, but I run the shield in exactly the same position almost all the time. I raise it when the bugs are REALLY bad. I lower it when it's raining to get more air on my faceshield which helps keep the rain moving off.

It's been such a sudden drop in mileage that I thought perhaps something might be wrong with the bike that I am not realizing. But it seems to be mostly attributable to the winter gas mix and the extra warmup times.

NC misses you Grumpy. Come home and ride!

 

[krashdragon]

Perhaps the BTU rating of gasohol is only 3% less, but once I leave the "Golden State" and the metropolitan area of Reno, my gas mileage jumps from 38-40 mpg to 48+ mpg. That's considerably more than 3% difference. Even riding twisty roads from Moscow a couple of years ago I was getting in the 46-47 mpg range. A drop from 46+ mpg to 40 mpg is more in the 15% range.
The above differences were on the '04 with a "AMAHAY" windshield, but I've noticed similar results on the '05 with a CeeBaileys +4+3.

Anyone else who travels into different states with "real" gasoline rather than gasohol notice as drastic a change?

yes, even last April I was getting 43mpg on the last tankful I bought in Cali... after that, went back to 43 mpg... oh yeah... this was on the Harley, noticed the same thing happened with the JFR and my Jeep on return trips this summer.... except in Montana... have no idea what they put in the gas there, but my milage drooped there as well...

And the gas in New York state looks like greasy dishwater... NO idea what they do there....

But as I sit here in Frostbite Falls, Ohio grumbling at my friends in Hawaii complaining about how hot it is....

Hawaii does not experience much difference in temps, ok, it might get down into the 50's, and it gets up into the 90's in the summer. BUT...

Did you ever notice the calibration stickers on each gas pump...?

They take a calibrated can and measure the ampunt of gas, if it's not up to specs, then they have to adjust the pumps... The calibration takes into account the TEMPERATURE , you dont' get as much gas in the summer as in the winter. There was a lawsuit in Hawaii, basically saying the people wer gypped cause we were only getting the summer amount, and not the greated amount of gas during the cold weather... no cold weather there... (heat= expansion)

My ex is a calibration technician for the Navy in Hawaii.... otherwise I'd have no idea about this...

So it's gptta be the additives, and they are different for different states.... winter gas vs summer gas....

anyway, dumb question... how can gas be "oxygenated" anyway? Isn't that like the shampoo with all the bubbles in it, where we're paying more because it's full of air? Oh well...

Mary

 

[HaulinAshe]

It's supposed to be cold blowing rain tomorrow. Maybe I'll break down and try the cager on the same gas. That should answer the question.