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Old 06-16-2022, 06:13 PM   #1 (permalink)
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Alternative MPG Calculation

I just wanted to verify my thinking and math with the tools I have. I run a Holley Terminator X and I can take logs of short trips and sections of drives. In the logs I can see my overall fuel flow in lb/hr and speed in MPH. I setup a spread sheet of a log of my daily commute to work and the average speed was 35.87 mph and found the average fuel flow to be 12.75 lb/hr for the whole trip. My question is the formula based on these values. I have been using this formula.

(speed)/(fuel flow)*(weight of gas/gallon)
My understanding is a gallon of gas is 6.3lbs. In the above case I got 17.44mpg but at the pump doing the tradition calculation I have been multiplying the miles by 1.09. I have comparred the Jeep ODO to a GPS and the GPS reads higher by about 9%. So when I multiply the speed by 1.09 and do the calculation again, I get just over 19mpg.

Does my barely passed highschool math check out or am I wrong? I have been making some lean tunes and so far the best I have gotten was 16mpg for the last 2 tanks using a corrected speed and 13mpg before that, so I am a bit skeptical I did this good.

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