Um...impossible gallons per hour?
Yesterday, a friend and I (please notice the friend - he bears witness
to this and was more than willing to provide evidence as he didn't
believe it either)) took the Ranger out for it's initial long term
test run and a little fishing around Fisher's Island and The Race.When we left the house, we stopped to top off the Ranger's fuel tanks
- right to the tippy-top of the tank - couldn't stuff any more into
the boat. Never shut the E-TEC 200 HO off the entire time we were out - four
hours of constant running - idle (600 rpm), trolling (600 rpm), cruise
speed (35 mph @ 4100 rpm) and about six/seven minutes of WOT (54 mph @
5400 rpm). Four house of run time. Refilled on the way home - same deal - right to the tippy top. Ok, here we go. 4.883 gallons of gas. That works out to 1.22075 gph. I don't believe it either, but them's the facts as they say. And if anybody calls me a liar, I have a witness who is willing to
"testify" as it were. :>) |
Shortwave
Aug 10
2006
|
| I hit up one of our chemical engineers and ran the scenario about fuel
expansion by him and he agrees with Shortwave's formula. In other
words, a 40 gal fuel tank that was filled when the fuel temp (not
ambient) was at 60F and then raised fuel temp to 110F (which would be
hard to do) or a difference of 27.78C will only expand 0.1112 gallons,
or less than a pint. I think what people perceive as fuel expanding in a cold tank is
actually the fuel vapors expanding. They don't have anymore fuel,
they are experiencing fuel vapors expanding tanks, pushing fuel out
vent hoses, etc. Fuel vapors are much more apt to expand, something
like 1.5% per deg Celsius (much higher than the .01% of a liquid), plus
accounting for the low boiling point of gasoline and presto, a cold
tank of fuel becomes a pressure cooker when the ambient temp goes up 15
to 20 deg. No extra fuel, just a lot of extra vapor molecules pushing
on everything else. So with that info, Shortwave is either A) Getting really good HPG, B)
Didn't fill up the second time as high as the first time, C) Idled
much more than he thinks, D) Is an out right liar... But he didn't
experience significant fuel expansion. My bet is on A. |
Joey916
Aug 11
|
| I agree. If you work the formula that I provided, you'll see that the
fuel expansion idea doesn't fly! On the other hand, I was reading in an
Engineering magazine that the Concorde, because it flies so fast that
friction heats the airframe so that it actually gets 7 to 10 inches
longer! |
basskisser
Aug 11
|
| Oops. Sorry Bass, I gave Shortwave credit for the formula you found...
My bad. |
Joey916
Aug 11
|
| The real test is to plot you usage over several trips against you
running hours meter. I log my gas, along with the other things you
shouild be logging to keep track of maintenance items.
That way you can get a picture of how things are going. |
gfretwell
Aug 11
|
| Not a problem, most of us in this thread have come to the same
conclusions! And I agree with your assessment that some people were
thinking vapor as opposed to the liquid. |
basskisser
Aug 11
|
| Fuel was higher temp at the end of your run, taking more space. jps |
jps
Aug 10
|
| following well considered thoughts to the readers of rec.boats:
Memory says between 6-700 RPM....
|
Gene
Aug 10
|
| After some "thinking" about, and calling a friend in the oil business,
I have to agree with you. |
Shortwave
Aug 10
|
| An E-Tec is the most fuel efficient outboard out there. "Shortwave Sportfishing" <onetwothree@four.com> wrote in message |
Ron
Aug 11
|
| Maybe some kind of "air lock" when you refilled? |
ACP
Aug 10
|
| My old 135 Evinrude takes that much to get out of the idle zone at the
marina!!!!! |
basskisser
Aug 10
|
| It is possible as the E-TEC idles at 0.18 gallons per hour, which means it
has to run over 5 hours just to burn 1 gallon of gasoline. Combined with
cruising to and from the trolling area, you can have remarkable fuel economy
when you average the numbers. Most folks are amazed at the milage they get with an E-TEC because when you
look at the usage profile stored in the engine's computer, over 50% of the
time the motor is run below 2000 rpm and that consumes very little fuel. Bill Grannis
service manager |
Billgran
Aug 10
|
| following well considered thoughts to the readers of rec.boats: |
Gene
Aug 10
|
| That's a bad idea. |
DSK
Aug 10
|
| Huh? Maybe I should only drive on hot days. Eisboch |
Eisboch
Aug 10
|
| To calculate change in volume, the formula is very much the same as for
change in length; only a few particulars are different. In the formula
dV bVOdT, the last term, again, means change in temperature, while
dV means change in volume and VO is the original volume. The letter b
refers to the coefficient of volume expansion. The latter is expressed
in terms of 10-4/=B0C, or 0.0001 per =B0C |
basskisser
Aug 10
|
| I thought of that, but the way the boat sits on the trailer, live on a
hill and have to go ten miles to get to a gas station on the way there
and about the same on the way back, that's highly unlikely. |
Shortwave
Aug 10
|
| I'll tell you, it really shocked me when I saw the bill - compared to
my 225s, that's pretty significant. |
Shortwave
Aug 10
|
| I wish I had taken the time to write down the cruise and run times.
Next time I will. I was amazed with the other boat, but this was spectacular. Is that email addy good - just remove one of the names? I'd like to discuss something with you if you wouldn't mind. |
Shortwave
Aug 10
|
| Well, despite the fact that four strokes are an inferior technology
(just joking), that's about right. Curious - what is the idle rpm for those beasts? |
Shortwave
Aug 10
|
| I understand why you would think so, but for the short term and the |
Shortwave
Aug 10
|
| Idling and trolling use *very* little gas... even my old tower of Power can
match those numbers trolling at 600. The real question is how much time
were you at 4100?? -W "Shortwave Sportfishing" <onetwothree@four.com> wrote in message |
Clams
Aug 10
|
| I'm sure!! That's a hell of a fuel savings. |
basskisser
Aug 10
|
|
No way. "Several gallons"? Maybe if you had a 10,000 gal tank, gas or
diesel. Eisboch |
Eisboch
Aug 10
|
