Fuel Gauge

[windstrings]

Possibly a bit off topic, but it seems that years ago they were selling a small half gallon or so container of something that you could use instead of gasoline, so it was much safer transporting it all the time in your car, and then you wouldn't be stranded.  But I never see anything like that anymore.

Walking down the rabbit trail with you!.....
Humm.. something I have heard no one ever mention?
I"m not sure how much gas weighs per gallon.. but water is 8.3lbs per gallon. Adding an additional 10 gallon tank would add approx 80 lbs to the rig..... like the trucks to... you would have a switch to change over when the other one runs dry..... this would allow over 1000 miles of driving between fillups... really nice if you find that really low priced station!..
I don't know if there would be issues with vapor etc... all else fails you could tap into the existing system and use without a switch?

[engunneer]

Warning... I am an engineer!

Originally posted by windstrings+Nov 17 2005, 01:39 PM--><div class='quotetop'>QUOTE(windstrings @ Nov 17 2005, 01:39 PM)</div>

The chart is part of my spreadsheet. The one I pasted was created at work, so it didn't update the one on the web, but now I've done it at home too. Click the link in my sig to see my live spreadsheet.

<!--QuoteBegin-IsrAmeriPrius@Nov 17 2005, 03:05 PM
It does not affect the actual MPG, but it does affect the manually calculated MPG.

Let's say you drove 500 miles since the last fill up.  The pump stops after 8 gallons.  That calculates to 62.5 MPG.  If you were to top off and squeeze in another 2 gallons, your MPG calculation will drop to 50.  Of course, this will only apply to the individual tank.

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The interesting thing this brings up is how to do the calculations. This is a little hard to explain in text, but I'll try

I now have two data pages on my spreadsheet. One calculates the "normal" way where I fill in wach row as I put gas in. (Page "Data" on my spreadsheet.) The scond one calculates how far I went on this tank based on how much gas I put in last time. ("Shifted Data"). I fill in everything as normal, except I put today's odometer reading on the previous tank. The gas I put in today has no miles on it yet. Calculating this way moves the variability away from how much gas I put in, and moves it to how much I had left when I filled. 90% of the time, I fill at the beginning of the trip on my way home from work, when the tank is at one pip.

On the "tank miles per allon filled" graph, you can see that the shifted data trendline (the linear one) has a formula of 49MPG(Filled) - 28 Miles. To me this means that I average 49MPG, except I take a 28 mile hit to the tank because of warm-up. Percentage wise, this works out weel with the % of my commute spent warming up (about 8 minutes out of 60). Notice that this trendline is close to the green line, which is just a linear plot of my current MPG average (unshifted, but shifted and unshifted MPG are almost the same).I've also drawn in the 50MPG "target" line.

On the non-shifted trendline, it indicates that no matter how much gas I put in, I get 270 miles free, plus 17 miles for every gallon filled. This is obviously a less accurate (logical) way of figuring out how far I can go per tank.

For both linear trendlines, the R squared value is barely better than .6, meaning there is alot of fluctuation in my datapoints, but I think it's OK.

The polynomial trendline on the shifted data is less clear as far as the formula, but it gives a better R squared value, meaning it fits the data better. Theoretically, I would always want to be on this poly plot, closest to the 50MPG "target" line to get the best MPG. This point is at approx 8.75 Gallons, where I should get 420 miles per tank. This should get me up to 48MPG in theory.

Obviously, I need more datapoints.

[engunneer]

I updated the "Tank Miles per Gallons Filled" Chart to include lines for 35 through 60 MPG in 5 MPG increments, and tried to make things a little easier to see. It looks a bit confusing at first sight, but I made the datapoints smaller to be easier on the eyes. The important thing is how the pink line lines up with the teal line, showing how the "shifted" method calculates (seemingly) better per tank MPG.

Most of the graphs are based on the "Unshifted" data, however, since it's a lot of work to update them.

Are there any more correlations I should plot?

[windstrings]

Originally posted by engunneer@Nov 18 2005, 10:42 PM
I updated the "Tank Miles per Gallons Filled" Chart to include lines for 35 through 60 MPG in 5 MPG increments, and tried to make things a little easier to see. It looks a bit confusing at first sight, but I made the datapoints smaller to be easier on the eyes. The important thing is how the pink line lines up with the teal line, showing how the "shifted" method calculates (seemingly) better per tank MPG.

Most of the graphs are based on the "Unshifted" data, however, since it's a lot of work to update them.

Are there any more correlations I should plot?

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Wow!...I'm not too proud to admit you lost me awhile back!
But I do admire your charts.... I know they make sense to you and I appreciate your attempt at explaining them... I suppose If I studied them long enough I might soak up a little bit.....
Very impressive.....
I assume you work for Toyota.. if you don't, I hope your not working for the enemy!!! :P

[engunneer]

Originally posted by windstrings@Nov 18 2005, 11:32 PM
Wow!...I'm not too proud to admit you lost me awhile back!    
But I do admire your charts.... I know they make sense to you and I appreciate your attempt at explaining them... I suppose If I studied them long enough I might soak up a little bit.....
Very impressive.....
I assume you work for Toyota.. if you don't, I hope your not working for the enemy!!!        :P   

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I actually work for a company called Flow. We can cut almost any material using ultra high pressure water, with added abrasive (sand). Good explanation here. Our equipment is used to cut composites (like carbon fiber) on every single production composite plane manufactured in the world (or so marketing tells everyone) The only thing I've ever heard of that can't be cut is tempered glass, and noone can really cut that.

As far as the charts, what part do you not understand? I would be more than happy to explain more. By plotting diferent variables vs other variable, we might find some combination of data that shows a good way to improve MPG. (Like my theory of always filling up with 8.75 gallons)

[windstrings]

Originally posted by engunneer@Nov 18 2005, 11:46 PM
I actually work for a company called Flow. We can cut almost any material using ultra high pressure water, with added abrasive (sand). Good explanation here. Our equipment is used to cut composites (like carbon fiber) on every single production composite plane manufactured in the world (or so marketing tells everyone) The only thing I've ever heard of that can't be cut is tempered glass, and noone can really cut that.

As far as the charts, what part do you not understand? I would be more than happy to explain more. By plotting diferent variables vs other variable, we might find some combination of data that shows a good way to improve MPG. (Like my theory of always filling up with 8.75 gallons)

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I've heard about the cutting technology you speak of.. its quite facinating!

I will need to study your charts more before I give you some decent feedback.... I need to give them an honest chance... they are quite overwhelming!
Thanks...

[skruse]

I appreciate revisiting fuel gauge pips. My first pip goes at ca. 125 miles. I drive the same route each day (60 mi round trip) and the central pips "average" about 50 miles + or –. I can easily judge if I am going to earn 600 miles on a tank. Because of repeated discussion here about running out of fuel, I always fill up when the last pip starts blinking.