Fuel weight
 

Just a thought that I haven't previously seen posted. Every one knows that gasoline weighs around 6 pounds per gallon. Have any of you put smaller tanks on you cars or do you only put 2 to 5 gallons in at a time?

I seem to remember that every extra hundred pounds in a vehicle costs about 1% in fuel economy. So If a max of 5 gallons were used instead of a fillup of say 12 gallons, that would save around 42 pounds of weight on a consistent basis. If a smaller tank were installed you might save anothe 5-10 pounds in weight.

Just wondering if anyone has done this yet.

JJ

Probably, but with People who drive Jeeps as a recreation, All I hear from them is adding ANOTHER tank to their Jeep so they can go farther without filling back up again.

It'd be even more with an SUV, especially because some tanks are up near 40 or 50 gallon tanks. or even more. Mine's a 23 gallon tank.

It's probably been done, although I don't know of anyone here that does it. The only problem I see is less accurate fuel data if you don't have instrumentation because you have less gallons to judge on every tank, you you mileage might be crazy high one tank and really poor the next if you only had 2-5 gallons to take measures from.

I have run multiple 5 gallons fills in a 15 gallon tank with no appreciable increase if FE. It does accelerate better but it was a hassle to fill up every 2-3 days. There is no doubt that lighter equals better FE but I don't think that this is something that will show up on the fuel gauge. Kind of like getting rid of the spare. In the long run I want to get home. YMMV.:turtle:

Try 5 gallons in a 50 gallon tank. that'd be like getting rid of all your friends who need rides! :D

Actually 5 gallon in a 50 gallon tank is probably less percentage wise then the other way around just because of the empty weight of the cars if taken as a percentage. Don't know but if it has a 50 gallon tank all 5 gallons is going to do is take you to the gas station to fill up again.:D

yea, but who takes that into factor? wait.. I do CRAP! I wonder what a geo would look like with a 50 gallon tank *ponders*

I'm torn between wanting to calculate my actual fuel consumption (by doing a complete fill up) and wanting to minimize weight (by doing more frequent small fills & then relying only on the SG to tell me my FE).

If I could easily remove fuel from the tank after filling up, I'd keep it in gas containers and add it back as needed until the next refill.

I've tried syphoning from this car's tank before, however (when I bought it - to remove the 7 year old gas that was in it), and I couldn't get a hose into the tank. Ended up having to get under the car & remove the filler pipe from the tank to get the tube in.

It's too bad there wasn't an inflatable bladder inside the gas tank. You could inflate it to 10 gallons in a 15 gallons tank and fill'r up with just 5 gallons. :thumbup:

There's some lateral thinking!

Perhaps this thread applies more to those who already have extremely high efficiencies. If one is already getting 50-60 mpg I would think it unusual to run out of gas with a 200-300 mile range(4-6 gallons).

Great idea. Just have to keep it away from the fuel output line.

Which leads to a question I've been meaning to ask. Does the SG actually calculate the fuel economy or is it reading that info from the vehicle's onboard computer? I understand that the SG can tell you how much fuel is left in the tank by doing the full tank calibration sequence, but since it already reads the fuel efficiency before the tank cal is performed, then one of the two previous assumptions must be true.

Lazarus, if the vehicle accelerates better I would have to think that is due to the lighter weight. However, because of the lighter weight and the fact that an increase in acceleration is noticeable, maybe backing off on the throttle upon acceleration would make the difference in fuel economy more apparent.

Again, these are just a few thoughts I have. Other than the fact that for years I haven't filled my gas tank completely unless going on a longer trip, I haven't actually tried any readings myself as my new SG just showed up yesterday. And it works in both my Fords. Only the unit itself was sent(no cable). Just glad it wasn't a bad cable.
JJ