Bad gas mileage

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1973dusterkid

1973dusterkid

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Ok so I did some calculations and I found out my gas mileage.

I can run 160s on a tank and my tank is (I think 16g) so that's 10mpg that not good for a /6 is it.
 
those big tires on the back are throwing off your odometer.
 
1973dusterkid said:
Ok so I did some calculations and I found out my gas mileage.

I can run 160s on a tank and my tank is (I think 16g) so that's 10mpg that not good for a /6 is it.
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you figuring out mileage properly?


divide miles by the gallons it took to fill..


plus like stated it you have taller tires on the car and didn't put the proper speedo gear in for the tire height then your showing less miles then you actually went.
 
You can adjust your calculations to compensate for the different tire size using this: http://www.miata.net/garage/tirecalc.html

Or measure distance with GPS, which I have done. BTW, my '73 Duster with bone stock 318/auto with 2:76 gears in the 7.25 gets 16mpg with roughly 50/50 highway and in town driving if I drive responsibly.
 
im getting about 17 with a 2 barrel V8 and 2.76s with a 73 duster, with gas coming out of the neck to bone dry.
 
1973dusterkid said:
i checked with and the milage is still pretty accurate with the tires.
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You checked with what? GPS is the only way to tell at this point, if you didn't change out your speedo gear in the trans. With a GPS unit you can check actual miles driven and your speed.
 
Yes, easy to make errors calculating mileage.
By brother used to use the "I get *** miles out of a tank, I think I have a YY gal tank, therefore I get ZZ MPG" method, and he was absolutely WRONG.

You gotta know tha actual miles traveled and the actual gallons used.
WRITE IT DOWN. Don't try to remember it.
Better to do it about 3 times to avoid anomalies.
 
Hey Badsport you must be a young techie. I'm an old guy and use the old school method of checking speedo and odometer against road milemarkers..
 
Badsport said:
You checked with what? GPS is the only way to tell at this point, if you didn't change out your speedo gear in the trans. With a GPS unit you can check actual miles driven and your speed.
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If you know the percentage of error, you can correct the calculation. However it's one more thing to fudge up. Not to mention different brands of the same size tire measure differently new, and of course the diameter changes (albeit very little) as the tire wears. I fill until it shuts off, drive (using my GPS to measure miles), refill until the same shutoff, preferably at the same pump, and divide. You can do a partial tank, since you are only measuring the fuel consumed, but the more miles, the more accurate the test will be. Which is a great point to average three tankfuls, as suggested.
 
Hi Keith,
The above posts have been right on, you can't go by the size of the tank - only the amount of gas you put in it at each fill up.
Thanks again for the seat, hope to see you at Summit in May,
C
 
3406pk said:
Hey Badsport you must be a young techie. I'm an old guy and use the old school method of checking speedo and odometer against road milemarkers..
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Mile markers aren't always exact. They are allowed so much leway placing them. Should beable to get close though.
 
The only way to use the amount the gas tank owns is to run it dry, fill it up and record the gallons, then run it dry again.
 
The tires a quite a bit taller not sure how much I filled it up Sunday and I have 155 miles on it now.And I was very close to empty.So in the morning when I go to school I will fill it up.

I held 14.3 gallons when I put gas in Sunday (not completely empty).I have ran 155 miles on this tank and am almost empty.

I have been using my dads GPS for the last couple of days and after the speedo reads 155 the GPS (garmin) my speedo is 2-3 miles off.
 
clhyer said:
Hi Keith,
The above posts have been right on, you can't go by the size of the tank - only the amount of gas you put in it at each fill up.
Thanks again for the seat, hope to see you at Summit in May,
C
Click to expand...


Yeah I am waiting on the show at summit and year one
 
1973dusterkid said:
I held 14.3 gallons when I put gas in Sunday (not completely empty).I have ran 155 miles on this tank and am almost empty.
[/QUOT

The best way to know how much fuel you used is to fill the tank, then after you've driven the car x amount of miles, fill it again...that's how much fuel you used.

I bet you are getting more than 10 mpg.
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