Announcement

Collapse
No announcement yet.

gas mileage = WOW

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Re: gas mileage = WOW

    Originally posted by BRodri View Post
    that is strange on one of the pumps i use in oklahoma it says like 102 cu. ft is a gge. i think that would change with the temp wouldn't it?
    Many don't realize that the makeup of the gas can vary widely around the country. A gge is based on the amount of gas that has the same energy content as a gallon of gasoline.

    As has been pointed out, even gasoline varies depending on where you're at, and how it was blended, or for who. Some areas of the country has "hotter" gas based on the amount of other gases remaining in the mix, and the % of methane being dispensed. Your local gas co can provide you with the content of your gas, as well at the btu rating, etc.

    Comment


    • #17
      Re: gas mileage = WOW

      Originally posted by Curtis View Post
      (snip)
      As has been pointed out, even gasoline varies depending on where you're at, and how it was blended, or for who. Some areas of the country has "hotter" gas based on the amount of other gases remaining in the mix, and the % of methane being dispensed. Your local gas co can provide you with the content of your gas, as well at the btu rating, etc.
      Interestingly enough, at the CE station in Santa Clarita, CA one 3.6 Kpsi pump says at least 88% methane. The other says at least 90%.

      Guess which one I use.

      Bill

      Comment


      • #18
        Re: gas mileage = WOW

        Originally posted by Cal View Post
        250 miles with three bars left! I filled up at the CE Santa Clarita station. OH, WOW!

        I've used the CE station in SC and have seen the same results. At the same time, I've filled the tank, then came back 3 hours later, topped off the tank with another 1.1 gallons. THEN, I've got 255 miles with 2 bars showing.

        Comment


        • #19
          Re: gas mileage = WOW

          OK,
          It took some time to get this out as I wanted to poll more data. After 5 fueling events here is what I came out with.

          Same pump/pressure: Temp +/- 2DegC during fills
          2009 GX
          41mpg
          280 miles per tank with ~2 bars remaining.

          To be on the safe side I calculated that each bar on the gauge readout equals approximately 0.350 gallons which is roughly 14 miles per tick.

          Obviously this is just a generalization as pumps/temps/pressure fills etc etc are factors that can sway results but this is the best data I can come up with so far.
          Silver 09 GX
          Phill G:1.5

          Comment


          • #20
            Re: gas mileage = WOW

            Just my 2 cents worth.

            If the attachment uploads correctly it shows data from my new 08 GX taken for every fill from the point I bought it in May of this year.

            Done 11k+ miles since then, mostly pounding i-880 between Berkeley and San Jose (don't even get me started on that commute!) Generally either going 70+ in the HOV lane or <10mph either side of the ludicrously slow progressing Mission blvd roadworks.

            I would certainly agree that the fills seem to be variable to say the least and assume mpg figures are going to be up and down based on numerous factors described in this thread.

            Personally, I've never got more than 230 on a tank full and seem to be averaging about 34.5 mpg.

            Andy
            Attached Files

            Comment


            • #21
              Re: gas mileage = WOW

              Andy,

              That spreadsheet is awsome! Great work.
              Mine is much similar but my data spans only a month.

              Silver 09 GX
              Phill G:1.5

              Comment


              • #22
                Re: gas mileage = WOW

                Andy,
                I'm curious, how did you determine the actual volume when you fueled @3000psi?? linear??
                Silver 09 GX
                Phill G:1.5

                Comment


                • #23
                  Re: gas mileage = WOW

                  Originally posted by lcovelli View Post
                  Andy,
                  I'm curious, how did you determine the actual volume when you fueled @3000psi?? linear??
                  Whatever it says on the pump. It doesn't matter. Just like with regular gas, doesn't matter how fast it goes in or how full it gets, long term

                  Comment


                  • #24
                    Re: gas mileage = WOW

                    Icovelli --> I just make a note of the volume the pump says. Very unscientific I know.

                    Andy

                    Comment


                    • #25
                      Re: gas mileage = WOW

                      In the US, product being sold to a consumer by either volume or weight must be through a certified meter or scale. Most of the CNG dispensers have a complicated metering method, either with a vane meter or a coriolis effect meter (MicroMotion is the most common). This meter is calibrated with known values which include the fuel density, temperature, and pressure, the BTU value, and a plus or minus tolerance, and finally the Bernoulli effect. The final product is delivered converted in gasoline gallon equivalence (GGE).

                      To convert, take the BTU value of CNG, generally 1025 BTU's per cubic foot (this varies nationwide but is a close approximation, call your gas utility for your actual number). Gasoline has approximately 125,000 BTU's per gallon, but that too changes nationwide and also with how much Ethanol is mixed in. With these two numbers, divide the gasoline BTU's by the CNG BTU's, and we get 121.95. This is the number of cubic feet of natural gas that is required to provide the same heat value as a gallon of gasoline, or a Gasoline Gallon Equivalent.

                      This is what the meter is calculating based on the above factors. Its pretty close but it all depends on what the initial BTU factors are. The scale from the dispenser is not linear, nor is the fuel gauge in the vehicle. Every manufacturer uses a different value in dash gauges. The gauge may register slowly at the top (full) where the fuel is the most dense, and accelerate the movement as it reaches closer to empty.

                      Franz

                      Comment


                      • #26
                        Re: gas mileage = WOW

                        Here's the bottom line. When you buy "1 gge" of CNG, you can be pretty sure you're getting 5.66 pounds of gas, because that's how the authorities test the accuracy of the system, by weight. You just have to trust the gas supplier that the gas is XX% Methane and that the BTU content of your "1gge" is close to the BTU content of a gallon of gasoline.
                        02 GX
                        01 GX
                        03 Crown Vic
                        06 GX
                        Home Fueler

                        Comment


                        • #27
                          Re: gas mileage = WOW

                          Quick update at 20k miles.

                          Still gotta love that carpool sticker.
                          Attached Files

                          Comment

                          Working...
                          X