Can't break 40 MPG, should I be concerned?

[repoe3]

Originally Posted by bikerfish1100

that ethanol impregnated stuff sux, btw- worse fuel economy, weaker performance...ethanol sux.

yep and yep. thats what i noticed. been scratching my head why kevinSBX's stock 02 prep gets substantially better mileage. but then i had to consider the fact that he never sees stop-n-go traffic like i do in DC and he never has to run enthanol-blended fuels. add to that fact that my 04 is running a chip and a PCIII, its bound to brun a bit more gas. that said, even commuting, i dont get worse than 35mpg, so the light comes on around 125 miles. not bad for dense traffic. when out cruising, its more like 40mpg. cant complain, really, other than "ethanal sux."

repoe3

[DavidSoine]

I have been paying a little more careful attention to fuel economy lately...I am in the midwest (low elevation).

Last 2 expressway only runs: 43.3, 42.7 mpg
Last 3 around town/varied usage: 35.8, 33.4, 39.7

If you are not seeing 40+ on expressway only runs then I would be concerned. Around town or with varied usage, there is just too much variability in the fuel economy numbers to tell us anything really useful.

best,

Dave
99 R11S 69k miles.

[Daniel Restrepo]

if any of my bikes got 10 MPG i wouldnt ride it because i'd be at the gas station every 40 miles. how bad would that suck on a cross country tour or at a track day. you'd run out of fuel before finishing a 20 min session!!

[Guest24]

I get 153 miles from fill-up-tank neck not drilled- till the reserve light illuminates. City, Twisties or X-C all the same with nominal differences.

[Eisernkreuz]

From my experiments with 4 stroke internal combustion engines here at the university, if the engine has a load placed on it at 1800 rpm, it will suck gas at a much higher rate than if it was at 3600rpm. This was a direct-drive setup, no gearing. So, for those of you opening the throttle a lot from way down in the basement, you're getting worse fuel consumption than if you were to slightly open the throttle in a lower gear and higher rpm.
On the other hand, if you can keep it low rpm and small throttle angles, you'll get great fuel economy, but you'll be consistently beaten off the line by Priuses.

[markjenn]

Originally Posted by Eisernkreuz

From my experiments with 4 stroke internal combustion engines here at the university, if the engine has a load placed on it at 1800 rpm, it will suck gas at a much higher rate than if it was at 3600rpm.

I know nothing about your "experimennts" but this runs counter to everything I've ever read about IC engine fuel economy. Engine friction and pumping losses are highest at high RPM and small throttle openings. Best economy generally occurs at lower RPM and large throttle openings.

The general rule of thumb if you're stretching fuel has always been to short-shiift. Several of the car magazines have runs tests and found that using relatively aggressive throttle and short-shifting yields the bests fuel economy.

- Mark

[Eisernkreuz]

Ah, the old "sucking air against a partially-closed throttle" argument. It wasn't a constant-rpm thing. It had to accelerate against a water-pressure dyno. For the record, the engine was a carburated 200cc air-cooled ohv single But when loaded at 1800rpm, it ate 8mL of fuel in 18 seconds, vs something like 33s for the high rpm. But those things don't put out that much torque at 1800 rpm anyway, and from the way it was shaking, it wasn't happy hahaha

I think as far as our bikes go, the engine management system does a great job of figuring out how to make the most with the least regardless of what you're doing. I'm rarely above 4k on mine.

[ckcarr]

I get 50 mpg. Got slightly less with the r1100s but not much less.

But I have no traffic or rush hour to deal with and once I hit the road it's 5th and 6th gears only, usually. And importantly, I know every gas station within 100 mile radius of my home.


Of course the fuel economy ratings are BS anyway as the government standards call for 60 mph under a very light load.

[zimm]

After a couple thousand miles on the bike, I'm getting 45mpg around town with a mix of hwy- no heavy throttle, just commuting. At 75mph on the highway with the throttle lock on, I got 59mpg- 180 miles to the low fuel light. I thought the light broke and wasn't going to come on since it normally lights up at 140 miles around town.

[klennop]

Does the twin-spark improve mileage? I would think that it would help??

I noticed that his bike is a 99 so that would make it a single spark if that does make a difference?

[DavidSoine]

Higher elevation helps fuel economy on our bikes, as ckcarr has described. I regularly hit 50 mpg touring in Colorado - my buddies Sprint ST gets 60 there!

best,

Dave
99 R11S

[wswartzwel]

Yes I noticed the same thing, and could not believe the fuel mileage I got when riding in CO. However power was way down, and wheelies took some effort...

[pmc847]

I don't mean to hijack or start an argument on global warming or carbon foot print stuff but this is interesting.

To recap an earlier post,

My 03 BCR use to average in the low 40s and some times dip into the upper 30s. My 04 BCR has always been in the mid 40s and when out west 48 to 52 was not uncommon. Even after the mods it remained in the mid 40s. While out west this past Sept, driving the Passat, we averaged 15% better mpg and that is in states that have 5 and 10 mph higher speed limits. On our way home we got into Nebraska and got a tank of 10 % ethanol and our mileage dropped back to what we are use to here in WI. The next tank was ethanol free and mpg when back up. We have found some stations here in WI that sell ethanol free gas and our mpg have stayed consistently 15% better.

So I thought I would do a few calculations on the use of ethanol and our Passat, of course your mileage might vary.





Based on these calculations ethanol ( E10 ) is causing us to use more fossil fuel and therefore cost us more money per miles traveled and more pollution and still have the same dependence on foreign oil. This also doesn't take into consideration the amount of fossil fuel needed to make, and deliver, a gallon of ethanol vs. gas. Maybe E85 might prove to be the ticket but then again read the following. The ripple effect and costs might really impact the logic of using E85 made from food. Maybe the answer might be making ethanol from food waist products or other non consumables.

"Bio-fuel subsidies result from excessive lobbying from the bio-fuels industry just as much, if not more, than the true scientific merit of the technology. Consequently, we are missing out on the opportunity to judge whether bio-fuels are actually a viable future alternative fuel, and if so, to what extent. As such, society may be missing out on a more appropriate energy source in the future

Perhaps more importantly, the subsidization of bio-fuels is imposing a real and direct cost on people and the global economy in the here and now. When people’s demand for a product increases by more than its supply, prices rise. The growing subsidies and encouragement of bio-fuels use is increasing the demand for the source materials of bio-fuels: corn, sugar, soybeans and other crops at a faster pace than supply. Greater demand for agricultural goods is driving up food costs around the world. For instance, the price of corn is up 40% this year. The price of soybeans is up 75%. The price of wheat is up 70%. And, it is not just the prices of agricultural commodities. Higher prices for crops are increasing the prices of beef, pork, and chicken. According to the Bureau of Labor Statistics (the arbiter or consumer prices in the United States), while overall prices were rising 2.0% in August of this year, the prices of food and beverages were rising twice as quickly, at a rate of 4.2%. Rising food and grain costs are also squeezing many businesses, which can lead to lower profits, slower wage growth, more unemployment or a combination of these impacts should the squeeze continue.

Once these costs are recognized, it is difficult to describe bio-fuels subsidization as a win-win proposition. Instead, like everything else, encouraging the use of bio-fuels comes with a cost. Recognizing these costs is critical because in life, there is no such thing as a free lunch. " Wayne H. Winegarden Ph.D.


What do you think?

Philip

[wswartzwel]

Isn't ethanol a mixture of fossil fuel and alcohol... the alcohol coming from a renewable reource like corn... alcohol has less energy per gallon so it takes more of it to push you a mile down the road.... but it has less harmful emissions.... so even though you are getting worse mileage you are polluting less.


I have found that riding with certain people does allow me to score a free lunch every now and then..

[markjenn]

Phillip, while I don't think your E10 data is conclusive, it certainly is true that E10 mileage does suffer a bit compared to gasoline as ethanol has a lower specific heat content than gas. Everything else being equal, E10 mileage should be about 5% less and if cars are doing worse, that should be correctable through proper engine tuning.

On the larger political/economic issues of ethanol, I'm mostly in agreement with you - the current push for ethanol is not doing anything for our energy situation, nor the greenhouse gas problem, and is probably making the situation worse. And it's a boondoggle from a taxpayer standpoint.

Having said this, the biofuels proponents always come back to the need for short-term subsides to spur the technology forward towards critical mass and if we crack the technical issues of using feedstocks that are currently wasted (e.g., the corn husks rather than the kernels), then the economics and environmental impacts do shift dramatically back towards being positive. There is absolutely no doubt that long-term we need a transition strategy towards renewables that uses the current gasoline infrastructure as much as possible. And there are some applications (e.g. aircraft, plastics production), where we simply don't have good alternatives to the continued use of liquid petroleum products.

How to make the tradeoffs between short-term needs and long-term development? I won't tackle that, but I would view any current political candidate who is strongly backing biofuels in a negative manner.

- Mark

[markjenn]

Originally Posted by wswartzwel

Isn't ethanol a mixture of fossil fuel and alcohol...

Ethanol is just a type of alcohol (the same type in alcoholic beverages) produced from the fermentation process of biostocks like corn. It's what the "bugs" produce as a waste product during fermentation. There are lots of other types of alcohol such as isopropyl (rubbing alcohol) and methanol. (Don't drink either of these - they'll kill you!).

E10 is a mixture of 10% ethanol and 90% conventional gasoline. Most vehicles will burn it without modification. E85 is a 85% mixture of ethanol and 15% gasoline. Vehicles burning it need some minor modifications - they're called "E85 capable" or something like this. E85 is what the Indy race car series is using this year.

- Mark

[wswartzwel]

Thanks for clarifying that for me Mark... Ethanol is the alcohol, and the number following is the percentage of mixture with fossil fuel....


a Mass transit system would be a nice option ( electric bullet trains... Put my bike in the cargo bay... shoot down to moab and ride around with ckcarr)... but the masses have become such in the last 15 years that i do not really want to share space with them....

[pmc847]

Bill,

Yes, supposedly less pollution with E10 per gallon burned but you burn more fossil fuel going 1000 miles with E10 than you do with straight gas, based on our Passat.
I've asked some friends and relatives to experiment to see what they get.

Mark

I think E85 might be a good short term solution. I understand that E85 might get as much as 25 - 30 % less mileage than gas but even at that rate we would be saving a butt load of oil and pollution, I just hope the price per gallon is more reasonable. Also, a study out of Stanford U http://www.npr.org/templates/story/story.php?storyId=9647424 shows that ethanol pollutes as much and maybe more than gas.

Philip

[markjenn]

Originally Posted by pmc847

I think E85 might be a good short term solution. I understand that E85 might get as much as 25 - 30 % less mileage than gas but even at that rate we would be saving a butt load of oil and pollution, I just hope the price per gallon is more reasonable.

The big issue with biofuels in general is the land required. With current technology, we'd have to put about half the land area of the US under agricultural production to produce enough biofuel to meet current demand. And this a completely infeasible from multiple perspectives: land availability, land fertility, water use, etc. But things can be expected to become more efficient - there are some new hybrid strategies being proposed where biofuel yields can be increased dramatically if solar or nuclear power is used during the biofuel production process, for example.

It's unfortunate, but middle-east oil today is such a bargain that it makes other energy strategies difficult. It literally flows out of the ground like an artesian well, it's extremely high quality, and it can be economically shipped to any part of the world. Politically it sucks, and long-term we're going to look back at the way we frittered away the planet's cheap oil in the cosmic blink of an eye, but right now, it's a great deal. You can take the attitude of "enjoy it while you can" because in 100 years, things are going to change and change dramatically. We're in for some tough sledding.

- Mark

[pmc847]

I agree. If we could just pull our collective heads out of our duffle bags we could come up with some great alternatives as long as we keep politics out of it, fat chance. Here's an idea to save oil. Mandate that every vehicle produced in the USA or imported must have synthetic oil in the crank case and differential. Plus every oil change on vehicles produced after a certain date must use synthetic oil. Oil change intervals could be doubled so, theoretically, the cost to consumers might mean a minimal $ increase. Care to guess how much oil that would save?

Philip