Surprising increase in truck MPG

Ignoramus11166 wrote:
>
> On 2008-04-19, Doug Miller > wrote:
> > In article >, Ignoramus11166 > wrote:
> >
> >>It is a Silverado 2500HD pickup with a 5.9 liter engine, not sure
> >>about axle ratio.
> >
> > And it only has a 22-gallon gas tank?????
> >
>
> Yes. I would like to have a bigger tank.

Yea, 22 rather sucks. My 3500 has a 34 gal and it's not really adequate.
I've been thinking about relocating the spare tire, installing a 30 gal
Suburban tank there and replumbing to a dual tank setup. Still haven't
got around to it though.

Ignoramus11166 wrote:
>
> On 2008-04-19, Doug Miller > wrote:
> > In article >, Ignoramus15242 > wrote:
> >>I have a Chevy Silverado pickup that is by now about 18 months old.
> >>
> >>I was never able to get more that about 220 miles out of a 22 gallon
> >>tank of gas, sometimes even less.
> >>
> >>However, the last three refills, gave me 280, 266, and 283 miles per
> >>refill. (I usually run until my tanks gets fully empty, since I have
> >>an emergency gas canister for the instance when I run out of gas).
> >
> > Not a good idea, really. The in-tank electric fuel pumps that most
> > manufacturers are using these days depend on a continuous flow of fuel to keep
> > them cool. Repeatedly running the tank dry will dramatically shorten the life
> > of the pump.
>
> I do not run out of fuel, I simply get to the point of fuel needle
> being at the bottom and low fuel warning.

Once you get below around half a tank, the vertically mounted fuel pump
is no longer submerged. The motor still gets some cooling from the gas
flowing over it inside the pump, but you loose all the thermal
conductivity of gas around the outside of the metal pump housing
carrying heat away.

>
> >>This represents approximately 22% increase in MPG that I have hard
> >>times explaining. I see three possible explanations.
> >
> > Almost 26%, actually. (25.6 to be precise) <g>
> >
> > Please note, however, that you're measuring miles per *tankful*. Not miles per
> > *gallon*. Has the amount of gas that you're pumping changed?
>
> It did not.
>
> >>1) Just before those refills, I did an oil change and used Mobil 1
> >>synthetic oil. The previous oil changes were at a service station.
> >
> > You *will* see better fuel mileage with synthetics, but not 26% better. Two to
> > five percent, maybe, but not 26%.
>
> I agree.
>
> >>2) The engine had a chance to "burn in" and naturally improved its
> >>efficiency
> >
> > a) Anything of that nature that was going to happen, already happened a year
> > ago, and b) wouldn't make that much difference anyway.
> >>
> >>3) something is seriously mistaken in my measurements.
> >
> > You'd be the best judge of that. :-)
> >
> > Additional explanations that you've overlooked:
> >
> > 4) Warmer weather. Yes, it *can* make that much difference.
> >
> > 5) Other maintenance done at the same time as the oil change, maybe something
> > seemingly insignificant that you've forgotten about -- like making sure your
> > tires are properly inflated. Yes, it *can* make that much difference.
> >
> > 6) If you always buy your gas at the same station, it's possible that they
> > screwed up and put premium gas in the underground tank that's supposed to hold
> > regular. If your fuel mileage suddenly drops back to its previous level, I'd
> > be more inclined toward this explanation than any other.
> >
> > 7) *You've* been screwing up, and pumping premium instead of regular. OTOH,
> > I'd think you'd have noticed this the first time, when you went to pay for it;
> > seems unlikely you'd make that mistake three times in a row.
> >
> > 8) One really hot day, that raised the pressure inside the tank just enough to
> > pop out a large dent. You're getting more miles per tankful because you're
> > getting more *gallons* per tankful, but your miles per *gallon* hasn't
> > changed.
> >
>
> I like the suggestion of a different blend of gas, personally. (change
> from winter to summer blend).

That's a definite possibility and march / april would likely be when it
would change in most areas.

Not many years ago, didn't some cars have factory installed miles per
gallon gauges in the dashboard.I think J.C.Whitney.com company sells
some miles per gallon gauges.I have seen them advertised many years ago
in some magazines.
cuhulin

jim wrote:
> Studies in fleet vehicles have consistently shown that adding 10% alcohol
> to gasoline INCREASES mpg by about 3 to 5 percent. It is also well known
> that the addition of alcohol to gasoline results in higher octane and in
> more complete combustion of the fuel than gasoline alone. Which explains
> why energy content calculations mean nothing.

Cite.

--
"[i]t's not surprising, then, that they get bitter, they cling to guns or
religion or antipathy to people who aren't like them or anti-immigrant
sentiment or anti-trade sentiment as a way to explain their frustrations."
-- Barack Obama at a meeting with his equals, the elitist bourgeoisie

Ignoramus11166 wrote:
> On 2008-04-19, Doug Miller > wrote:
>> In article >, Ignoramus11166 > wrote:
>>
>>>It is a Silverado 2500HD pickup with a 5.9 liter engine, not sure
>>>about axle ratio.
>>
>> And it only has a 22-gallon gas tank?????
>>
>
> Yes. I would like to have a bigger tank.

So you don't drive the truck, you use it to store your investment gasoline.


--
"[i]t's not surprising, then, that they get bitter, they cling to guns or
religion or antipathy to people who aren't like them or anti-immigrant
sentiment or anti-trade sentiment as a way to explain their frustrations."
-- Barack Obama at a meeting with his equals, the elitist bourgeoisie

SteveB wrote:
>>> You check the odometer when you fill up. On your next fill, no matter
>>> if even a half a tank, you check the miles on the odometer again. This
>>> gives you the number of miles traveled and the amount of gas used to do
>>> so. Then you just divide the miles by how many gallons used.
>
> Do you really think this is a reliable way to establish mileage? Is this
> something new? Has this ever been proven? What would happen, say, if one
> would do this over ten tankfuls? Do you think this would give an accurate
> measurement over a long trip? Do you think anyone under 25 could do the
> math?
>
> WHAT AN OUTSTANDING NOVEL IDEA!
>
> Steve <g>
>
>
LOL.

My Jeep has had a gas gauge that works when it wants to, like maybe 2
years out of the last ten and I use the odometer all the time for
fill-ups.

We even take it on 3 and 4000 mile camping trips to the east coast.
When I hit 350 miles on my 20 gallon tank on a trip I know I need fuel
soon. I ran out once at 386 miles I think it was fully loaded running
hard (70+ mph which would be about 19 mpg). If I keep mine under 65
mph, I can get 21-22 mpg. Not bad for something with the aerodynamics
of a brick.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '08. Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com

> 8) One really hot day, that raised the pressure inside the tank just
> enough to
> pop out a large dent. You're getting more miles per tankful because you're
> getting more *gallons* per tankful, but your miles per *gallon* hasn't
> changed.

>snipped, a lot<
Hey Doug, actually he's not even getting that. He's only getting
*gallons per topoff as his gauge-needle approaches 'empty'*. And to be more
nearly accurate, it is all obtained as the needle approaches, but never
reaches 'E'. Remind anyone of "limits" in Calc 101? In older times a prof.
I had would say "as the needle approaches "E" asymptotically".
Enough of my bull***t. Romain and others got it right. I esp. enjoyed
being reminded of the variables mentioned: esp. the one about which spouse
is driving (quite true in my case as well). And I want to add one mo
expansion of gas with heat. Fill the tank *early* one morning when temp. is
much colder than it will be that evening when you return to the same spot to
re-fill it. Even with top-of-the-brim fills both times, the increased
temp., both ambient and of the vehicle itself, will yield an inaccurately
high mpg. Good way to impress a friend with how good your mpg is. Also to
help sell your used gas-hog to your penny-pinching, unpopular
neighbor--heck, let him fill it back up!
Luck to you, iggy, and you're correct to not expect great mpg with a 3/4
ton pickup. And as always, my input is based on my personal mileage and/or
beliefs. With price of gas, thanks to all who can help us do better.
s

"Ignoramus15242" > wrote in message
...
>I have a Chevy Silverado pickup that is by now about 18 months old.
>
> I was never able to get more that about 220 miles out of a 22 gallon
> tank of gas, sometimes even less.
>
> However, the last three refills, gave me 280, 266, and 283 miles per
> refill. (I usually run until my tanks gets fully empty, since I have
> an emergency gas canister for the instance when I run out of gas).
>
> This represents approximately 22% increase in MPG that I have hard
> times explaining. I see three possible explanations.
>
> 1) Just before those refills, I did an oil change and used Mobil 1
> synthetic oil. The previous oil changes were at a service station.
>
> 2) The engine had a chance to "burn in" and naturally improved its
> efficiency
>
> 3) something is seriously mistaken in my measurements.
>
> I am at a loss and am very puzzled. Can synthetic oil really account
> for that much of an increase? I highly doubt it.
>
> i

Any other changes? Tire pressure? Add a cap (shell or bed cover)?
Break in usually adds 5-10% mileage because of less friction throughout
the drivetrain.
Like others stated, running the fuel pump dry is not good for it, plus
the injectors should not run dry either since they rely on fuel for
lubrication.

In article >, clifto wrote:
>jim wrote:
>> Studies in fleet vehicles have consistently shown that adding 10% alcohol
>> to gasoline INCREASES mpg by about 3 to 5 percent. It is also well known
>> that the addition of alcohol to gasoline results in higher octane and in
>> more complete combustion of the fuel than gasoline alone. Which explains
>> why energy content calculations mean nothing.
>
>Cite.

Clifto, it's really simple.... they take 10 gallons of gasoline and then
add a gallon of alcohol. They then divide the miles driven by ten to
get their mpg figure.

Now if they divided by 11 it would go down because that gallon of
alcohol had less energy than a gallon of gasoline, but when they just
add alcohol and neglect its volume, they've added energy in the form of
alcohol but haven't corrected for its volume.

"SteveB" > wrote in
:

> I improved my MPG quite a bit recently. I changed my air filter.
> There are quite a few things one can do to improve mileage that are
> cheap or free.

Reducing speed by 5 MPH can also have a noticeable impact upon fuel
economy. <grin>

So can adding a bit of air pressure to the tires if they're not already at
maximum.

In city driving, shutting off the engine while waiting for the traffic jam
to resolve itself can save quite a bit as will any other technique that
reduces engine idle time. [Sweating uses less fuel than staying cool.]