I've always looked at the stickers on gas pumps here in Alabama that say "Unit must start from 0.0, government does not check accuracy" and wondered just how accurate the little spindle counting gas flow is.
Sponsored
Sponsored
- First Name
- Rough
- Joined
- Jan 9, 2022
- Threads
- 5
- Messages
- 682
- Reaction score
- 820
- Location
- Torrance, CA 90503
- Vehicle(s)
- Down to just the Mav
- Engine
- 2.5L Hybrid
My hybrid read 4.4% high until I recalibrated it with the AFE bias.
- First Name
- Mike
- Joined
- May 3, 2024
- Threads
- 4
- Messages
- 4,840
- Reaction score
- 4,393
- Location
- KC Metro area
- Vehicle(s)
- 2005 Toyota RAV4, 2024 XLT Hybrid
- Engine
- 2.5L Hybrid
Very true, I was waiting to get out of winter and have a full year of data.You're close. And I'm sure close enough. But still biased a little optimistic. With the fine control of 0.1% we have you could lower your bias by 1% or 10 more points out of 1000 seeing as you have data to back up that you are at 99% accurate in the long term.
IF it took a lot if effort, I'd leave it too.
Since it's easy, I'd probably adjust one more time. Maybe by 9 points out of 1000. Just because I can.
Then I forgot. I've gotta see what the current setting is and redo the math.
But for sure I'd rather be on 1 side of the line than the other for accuracy.
ETA - appears I did log it on my phone - so only the last 8 fillups were on new setting.
Was using 950 at that point, from prior value like 964 somewhere in there. So most of that data is adjusted readings already.
950x264.2/268.6=934
Last edited:
If the pumps that you are using are off.. you will get less gass than are indicated and that you are paying for... So you will 'appear' to be consuming more than you really are... That's always the case for me in Mexico (always pay for more gas than you actually receive 
).. My hand calculations differ from the Truck.. However, in the USA I'm not far off...
).. My hand calculations differ from the Truck.. However, in the USA I'm not far off...
Gasoline changes volume in temperature too. That's why jerry cans get bloated when it's warm out or if a dummy (me) leaves it in the sun.
https://www.ic.gc.ca/eic/site/mc-mc...nds.pdf/$file/VCF_Gasoline_Ethanol-Blends.pdf
So if you fill up at ~75 degrees F (25C), and then check at 60 degrees F (15C) the volume will be more than 1% different.
At least that's my current understanding..
https://www.ic.gc.ca/eic/site/mc-mc...nds.pdf/$file/VCF_Gasoline_Ethanol-Blends.pdf
So if you fill up at ~75 degrees F (25C), and then check at 60 degrees F (15C) the volume will be more than 1% different.
At least that's my current understanding..
Sponsored
- First Name
- Mike
- Joined
- May 3, 2024
- Threads
- 4
- Messages
- 4,840
- Reaction score
- 4,393
- Location
- KC Metro area
- Vehicle(s)
- 2005 Toyota RAV4, 2024 XLT Hybrid
- Engine
- 2.5L Hybrid
You might still find a tank above ground where ambient temp has any meaning to it.
Been awhile.
Do the breakdown from that 1% difference if actually true.
You don't get all the energy from that fuel anyway - heat loss.
So now what's left - would be interesting in actual tests if the difference is measurable, or only on paper does it matter.
- First Name
- Rough
- Joined
- Jan 9, 2022
- Threads
- 5
- Messages
- 682
- Reaction score
- 820
- Location
- Torrance, CA 90503
- Vehicle(s)
- Down to just the Mav
- Engine
- 2.5L Hybrid
Gas station fuel pumps are designed to have temperature compensation built in, and have a positive displacement metering system that's supposed to be accurate any any flow rate. However, my personal experience indicates that either the E10 blend we have available here in SoCal has lower density than published figures, or the stations have their pumps calibrated a bit on the light side (which would not surprise me). I've used accurate digital scales but NOT a graduated cylinder. Perhaps some day...If the pumps that you are using are off.. you will get less gass than are indicated and that you are paying for... So you will 'appear' to be consuming more than you really are... That's always the case for me in Mexico (always pay for more gas than you actually receive
My 'unofficial' test in Mexico was conducted using an empty 2.0L plastic gas can that took 2.2L to fill (indicated by gas pump) to the 2.0L mark. So there you go... Paid for 10% more fuel than I actually received. So, If I believed the pump when calculating fuel mileage, I would have had a number that was incorrectly 10% greater in the divisor, lowering the quotient.
I have not done this test in Arizona becuase my calculated and indicated are very close when stateside.
- Banned
- #24
Cans get bloated from the vapor pressure pressurizing the container. It's not from the liquid.
Try this: put 5 ounces of cold gas into a 5 gallon jug with good seal. Put it in the sun on a warm to hot day. It will "bloat".
- Banned
- #25
Well. While commendable to try mass and volume tests, you never know the exact blend of gasoline you have, so you never know the exact density it should be. So you won't know if it is correct or not.
E10 may be E9. Or E6.7! (Which makes it "lighter" but lighter actually means MORE energy in this case!!!)
And pure gas is never "pure gas". What about all the additives that vary station to station?
Last edited:
Sponsored
Thanks for sharing your view on it. I agree about the vapor contributing to the bloat. But the link in the quote shows the volume change due to temperature. It is a real thing.
- Banned
- #27
Oh yes it is. No doubt.
But have you ever filled a gasoline container with 100% liquid?
I never have. And unless you submerged your gas container in gasoline; and screwed the cap on while it was submerged, you will always have SOME air/vapor space in the container which contributes to 1000 times more "bloat" than the liquid will.
Sponsored
