Fuel Octane

[Lazy JW]

300-odd (miles)/wk here, typically.

One thing that people can do before pointing the finger, is track fuel usage via an Excel spreadsheet. The catch is, you really need to run it right down and refill fully each time for the most consistent/accurate findings. You need to fill in each of the categories and then manipulate the figures...

Date - Qty (gal) - Price - Distance - MPG - MPG averaged - Brand - Notes

Notes would include such things as unusual traffic events (changed engine conditions), variations to load or tyre pressure, different octane rating.

Oddly enough, it tends to stop a lot of the misapprehensions dead.

Hey, we don't need no stinkin' FACTS here bro :roll: :roll: How do you expect us to have anything to gripe about :

 

[addo]

Mrs Smith just read my post over your shoulder and said "That's a great idea. We can work out which car is most affordable to run."

Didn't she!

 

[Lazy JW]

300-odd (miles)/wk here, typically.

One thing that people can do before pointing the finger, is track fuel usage via an Excel spreadsheet. The catch is, you really need to run it right down and refill fully each time for the most consistent/accurate findings. You need to fill in each of the categories and then manipulate the figures...

Date - Qty (gal) - Price - Distance - MPG - MPG averaged - Brand - Notes

Notes would include such things as unusual traffic events (changed engine conditions), variations to load or tyre pressure, different octane rating.

Oddly enough, it tends to stop a lot of the misapprehensions dead.

Funny because I've done exactly that for the last 5 years. It is depressing to see how much money you spend on gas lol.

I buy the cheapest gas possible, and the correct octane for my vehicle.

My '98 Ranger get's 1 mpg more (24) with 89 as opposed to 87, no increase w/ 91. Synthetic oil made no difference.

My honda shows no increase with anything over 87.

No discernable difference with brand. I get a consistent 30 with my honda in mixed city/hwy commute as long as don't go above ~ 70 mph. Crusing at 80 mixed with city gets me approx 28.

Cruising at 55-60 mph nets 34 mpg! I try to hold ~ 65.

I'm not going to disclose how much I've spent on gas in the last 5 years, but I bet it would make some of you blush

Yup. Sadly, when accurate records are kept, most vehicles actually tend to get worse mileage at higher speeds just like EVERY ONE of mine have always done; still looking for the mythical car that gets better mileage the faster it goes.

I average 20,000 miles per year on my commuter rig plus another 10K on the family car, right at 19 mpg each. I keep meticulous records on the commuter rig but trying to get Mama to write down the gas for her Trooper isn't very productive

Gas here is about $3.70 for 87 octane.
Joe

 

[Lazy JW]

Mrs Smith just read my post over your shoulder and said "That's a great idea. We can work out which car is most affordable to run."

Didn't she!

Well, the Bug is the cheapest but she kept saying I was going to get run over by a truck; and I did Probably adding hospital bills into the equation will twist the results a bit, eh?
Joe

 

[66 Fastback]

I've heard that different fuel can make as much as a 10% difference in economy,

In Oklahoma, they just passed a law that will require the disclosure of any alcohol in the fuel. The old regs allowed them to have up to 10% alcohol without disclosing the information on the pump. As they have been spiking the gas with more alcohol, people have been complaining about a decrease in milage coupled with the increase in gas prices. So now there is a local backlash going on against corn fed gas stations. Many stations carrying 100% gasoline now have banners declaring no alcohol in their fuel.
Doug

 

[The Plankster Prankster]

300-odd (miles)/wk here, typically.

One thing that people can do before pointing the finger, is track fuel usage via an Excel spreadsheet. The catch is, you really need to run it right down and refill fully each time for the most consistent/accurate findings. You need to fill in each of the categories and then manipulate the figures...

Date - Qty (gal) - Price - Distance - MPG - MPG averaged - Brand - Notes

Notes would include such things as unusual traffic events (changed engine conditions), variations to load or tyre pressure, different octane rating.

Oddly enough, it tends to stop a lot of the misapprehensions dead.

thats exactly what i do. and that's where i get my statement that brand matters.

sure, they all come from the same pipelines, but the additive package makes all the difference!!

and on a side note, when you're setting up your spreadsheet, it's wise to check your odometer to see if a mile is really a mile. when you're on hte freeway, write down teh odometer reading as you pass a milepost (and write down the milepost number), then 20 miles later, do the same thing, and do the math so see how accurate it is. write that into your spreadsheet if necessary

and around here, ALL gas stations are required to have alcohol in the fuel. i believe it's 10%. i believe it's state law that requires it.
and in the truck i carry a bottle of alcohol to combat the wet environment...i've dumped several bottles into the tank.

 

[Lazy JW]

....

and around here, ALL gas stations are required to have alcohol in the fuel. i believe it's 10%. i believe it's state law that requires it.
and in the truck i carry a bottle of alcohol to combat the wet environment...i've dumped several bottles into the tank.

Ummmmm...... doesn't the fact that the gasoline already has 10% alcohol sorta make adding more alcohol redundant? Seems to me that it makes an already poor fuel worse
Joe

 

[addo]

Considering that ethanol is 1:1 miscible with water, that assumes an awful lot of water entering the fuel system!

Josh - I am pretty confident the odometer is accurate to within 1.5 percent.

 

[Harte3]

I am not a fan of alcohol laced fuels...or biodiesel for that matter too. Our 2004 Taurus is a flex-fuel vehicle so whilst hanging out at the office for a week near KC, MO I filled with E85...wrong thing to do. The first problem I noted was hard starting. The next thing was lack of power. And thirdly, the MPG sucked. It seems to run fine on E10 and ended up at 27.3 mpg running 70 mph from KC to Spokane. We will get 30+ going back the other way...it's down hill all the way.

Years ago I drove to work in Fresno, CA from Auberry, CA with a 170 powered Ranchero...fueled at cheapy marts and got four round trips from a tank. Started paying a few cents more at the Shell next door and got 4 1/2 round trips...well worth the extra few cents per gallon and cleaned up the tail pipe deposits from nearly black to tan.

 

[Bort62]

I am not a fan of alcohol laced fuels...or biodiesel for that matter too. Our 2004 Taurus is a flex-fuel vehicle so whilst hanging out at the office for a week near KC, MO I filled with E85...wrong thing to do. The first problem I noted was hard starting. The next thing was lack of power. And thirdly, the MPG sucked. It seems to run fine on E10 and ended up at 27.3 mpg running 70 mph from KC to Spokane. We will get 30+ going back the other way...it's down hill all the way.

Years ago I drove to work in Fresno, CA from Auberry, CA with a 170 powered Ranchero...fueled at cheapy marts and got four round trips from a tank. Started paying a few cents more at the Shell next door and got 4 1/2 round trips...well worth the extra few cents per gallon and cleaned up the tail pipe deposits from nearly black to tan.

Thing is, that is about as unscientific of an experiement as can be. I can think of about 400 variables that could skew your results OTHER than the brand of gas you were buying

 

[Harte3]

Agreed...but at the time I was not questioning the causes nor the results. I'll take another 1/2 trip and credit the tooth fairy if need be.

 

[Lazy JW]

..... I'll take another 1/2 trip and credit the tooth fairy if need be.

Yup. When my total cost per mile goes down I care not who gets the glory
Joe

 

[CoupeBoy]

I sat through a presentation a couple months ago about fuel usage, octane, ethanol, and fuel additives. The highlights of his presentation were
1. All 'Unleaded' in ND is E15, so that means 15% Ethanol max
2. All 'Unleaded' in MN is E15, 15% ethanol minimum (nice huh)
3. Use the lowest octane that does not ping
4. Do not add fuel line drying agents to fuel with ethanol, it's a wast of your money.
5. Do not use fuel with ethanol in small motors, most do not build the fuel systems out of material that will live long term being exposed to alchahol.
6. No flex fuel system will run as efficiently on E85 as it does on E15.
7. Somewhere in Fargo there is a gas station that still sells non-E15
8. Propane injection on diesels is a good thing
9. A truck that runs off of hydrogen with an 8ft bed has about 2ft of useful space after you load the tanks in the back.

If you want a completely un-scientific test check out these results, our normal DD gets on average between 18.5-23.5 on during our weekly 250mile driving to and from work. When we went to Jackson, Wyo 2 weeks ago we got better gas mileage the closer we got to the mountains, now is this due to slower speeds (which I would think would be offset by the increase in throttle required to climb mountains) or is it due to less Ethanol in the gas. Anyhow once we got to Jackson we took the next day to drive through Teton National Park and Yellowstone (most of which was still closed with large snow piles on the side of the road) we drove 210 miles and averaged 29mpg (45mph speed limit in park) so we wrote that off as a fluke. However the day we left Jackson down to Hoback Junction then over to Idaho Fall where we filled up, it was about 150miles (IIRC) and we averaged 35mpg*. Also when we used to take the '94 3/4t GMC down to Colorado the average would increase from 13-15mpg here in ND on the flatland to as high as 18mpg when we drove from Ft Collins over to Grand Junction.

So there you have it, live in the mountains and get better gas mileage (but I'm sure Joe already knew that).
-ron

*this is the number I will use when I sell it in the future "gets up to 35mpg!!!"

 

[ludwig]

5. Do not use fuel with ethanol in small motors, most do not build the fuel systems out of material that will live long term being exposed to alcohol.

I like this one the best. In translation it reads: "You cannot buy small motor fuel anywhere in California."

This also explains the clogging problem I had with my mowers. I thought it was the fuel breaking down. It was the tank melting from the gas. Now I pour the gas out of the tank and run the mower until it runs dry so there is minimal residual in the plastic tank.

BTW, Consumer Reports reports that ethanol has only 85% the energy of gasoline. Thus, the fuel efficiency as mile per gallon would go down as the alcohol in the fuel increased. This would account for some of the gain in MPG out west, CoupeBoy. In other words, "save the planet; drive less fuel efficiently".

 

[Bort62]

..... I'll take another 1/2 trip and credit the tooth fairy if need be.

Yup. When my total cost per mile goes down I care not who gets the glory
Joe

That's great until your total cost per mile goes back up and then you can't figure out why

 

[Bort62]

Yes, ethanol has less chemical energy than gasoline (there is a reason we use gasoline, after all).

Typically in an engine that is designd for use with ethanol you can regain and even surpass the loss in energy density by increasing the compression ratio. Ethanol's higher octane will allow you run a much higher comp ratio so you pretty much break even.

But running ethanol in a car designed for gas will give you pretty disappointing performance.

E10 has about 98.5% of the chemical energy of gasoline, so one could expect his mileage to drop from 30 to 29.55.

The presence of ethanol is certainly not responsible for multiple MPG loss.

YMMV.

 

[ludwig]

The presence of ethanol is certainly not responsible for multiple MPG loss.

Okay for you, Mr. Smartypants. It's not about what's really going on. We're trying to find someone to BLAME.

 

[addo]

I blame it on the bossanova.

 

[ludwig]

Put the Blame on Mame.




Add in: Why the heck aren't you at work,Addo? It's 9:15 in the morning.

 

[CoupeBoy]

Typically in an engine that is designd for use with ethanol you can regain and even surpass the loss in energy density by increasing the compression ratio. Ethanol's higher octane will allow you run a much higher comp ratio so you pretty much break even.

I was hoping a turbo setup with a manual adjustable wastegate would be an option so I can up the boost when burning E85 and drop it back down (ya right) when on "normal" E15.

Oh ya, I blame "The Man" who is trying to keep me down...

-ron