Gas shrinkage? - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 02-05-2007, 05:53 AM   #1
Registered Member
 
jwxr7's Avatar
 
Join Date: Jan 2007
Posts: 291
Country: United States
Gas shrinkage?

Lets say I fill my tank in 40 F weather, I'm still driving on that tank but now it is -10 F. Will it be a noticable change in volume? If so, then isn't that going to neg impact my FE for that tank, or is the denser gas going to "go farther"?

just wondering because it seems like my gauge dropped extra fast.
__________________

__________________
Best tank= 81.23 mpg on july 1st 2008
SAVE SOME GAS, SAVE THE WORLD!

jwxr7 is offline   Reply With Quote
Old 02-05-2007, 06:06 AM   #2
*shrug*
 
Join Date: Sep 2005
Posts: 6,195
Country: United States
Gas will change volume, slightly, perhaps, some argue not enough to be noticable. I don't know for sure. But it's unlikely to cause a noticable drop in fuel economy.
__________________

SVOboy is offline   Reply With Quote
Old 02-05-2007, 06:39 AM   #3
Moderator
 
GasSavers_DaX's Avatar
 
Join Date: Oct 2005
Posts: 1,209
Country: United States
The volumetric coefficient of thermal expansion for gasoline is about 950 x 10^-6 cubic meters per degree C.
GasSavers_DaX is offline   Reply With Quote
Old 02-05-2007, 06:51 AM   #4
Registered Member
 
Peakster's Avatar
 
Join Date: Sep 2006
Posts: 467
Country: United States
Allegedly it is quite noticeable. My Physics teacher once said that tanker trucks, when going from a hot location to a cool location, will suddenly have hundreds of dollars of less fuel than when they started out with if absolute volume was taken into play. This is why all the gasoline pumps I've seen declare "all volumes corrected to 15*C" to make sure everyone is paying the same price for gas.

There's been a few times where I'd fill my tank to the brim, drive around doing some arrands, and park my car in the garage. The next day, I'll try using a fuel additive and when I open the gas cap, fuel spurted everywhere!
Peakster is offline   Reply With Quote
Old 02-05-2007, 07:10 AM   #5
Registered Member
 
jwxr7's Avatar
 
Join Date: Jan 2007
Posts: 291
Country: United States
DV = bV DT (D is delta, b is thermal expansion coef, V volume, T temp)
If DV=.0095 m^3/C x .02712 m^3 x 27.78 C (.02712m^3 is 6 US liquid gallons of gas in tank, 27.78 C is change in temp) then my fuel changed volume by about .0005994 m^3 or .15835 US gallons or about 20 oz of gas. That could be equal to 8 - 8.5 miles of driving.

Probably not noticable with the fuel gauge.
__________________
Best tank= 81.23 mpg on july 1st 2008
SAVE SOME GAS, SAVE THE WORLD!

jwxr7 is offline   Reply With Quote
Old 02-05-2007, 07:14 AM   #6
Registered Member
 
MetroMPG's Avatar
 
Join Date: Dec 2005
Posts: 4,223
Country: United States
Quote:
Originally Posted by jwxr7 View Post
That could be equal to 8 - 8.5 miles of driving.
Except the amount of energy in your tank doesn't change with expansion/contraction.
MetroMPG is offline   Reply With Quote
Old 02-05-2007, 07:18 AM   #7
Registered Member
 
jwxr7's Avatar
 
Join Date: Jan 2007
Posts: 291
Country: United States
true, but does the engine actually get more energy when it burns the denser fuel or is it wasted by being too rich? May depend on car and state of tune.
__________________
Best tank= 81.23 mpg on july 1st 2008
SAVE SOME GAS, SAVE THE WORLD!

jwxr7 is offline   Reply With Quote
Old 02-05-2007, 07:20 AM   #8
Moderator
 
GasSavers_DaX's Avatar
 
Join Date: Oct 2005
Posts: 1,209
Country: United States
Quote:
Originally Posted by jwxr7 View Post
true, but does the engine actually get more energy when it burns the denser fuel or is it wasted by being too rich? May depend on car and state of tune.
This is why cars have o2 sensors - to compensate on the fly for this.
GasSavers_DaX is offline   Reply With Quote
Old 02-05-2007, 07:23 AM   #9
Registered Member
 
MetroMPG's Avatar
 
Join Date: Dec 2005
Posts: 4,223
Country: United States
I suppose it could have been true in the days of carburetors. Or pre o2 sensor FI (my old Rabbits all had FI, but I have no idea if they also had o2 sensors...)
MetroMPG is offline   Reply With Quote
Old 02-05-2007, 07:26 AM   #10
Registered Member
 
JanGeo's Avatar
 
Join Date: Jan 2006
Posts: 2,442
Country: United States
Send a message via Yahoo to JanGeo
I read in the Synlube site that gasoline expands and contracts about twice that of water - just looked for a while and couldn't find the actual numbers however. You still have the same BTUs that you bought at the pump - but you should buy the gas right after a cold snap to get it at its coldest temperature at the pump. Just be careful of expansion as it warms up.
__________________

JanGeo is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Matching EPA Type to My Car DastardlyDan Fuelly Web Support and Community News 2 10-26-2009 07:16 AM
Hydrogen or H2O Systems 1Jal1 General Fuel Topics 4 10-11-2008 02:20 AM
Coasting in Neutral Illegal??? 95metro Hypermiling 23 05-12-2006 06:50 AM
An American Perspective on Driving in Canada rh77 General Discussion (Off-Topic) 28 03-24-2006 10:42 PM
"active" aero grille slats on 06 civic concept MetroMPG General Fuel Topics 21 01-03-2006 01:02 PM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 11:51 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.