MPG Reality Check

[freewill2008]

Finally, after 7 years, I filled the fuel tank to the top, drove 1015 miles, and
filled it again. The 167 gallons calculates to about 6 MPG.

The method has plenty of potential for error. The odometer reads low and I
don't have a GPS. I used the Google mileage plus 5% to account for wrong turns,
finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and
Malibu, CA.

The tank is so big that I figure the fill could be off by as much as 10%. If
the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were 10%
high, the MPG would have been about 5.5.

Other details: 1984 FC31 with California 210HP turbo 3208. Road speed about 58
MPH. 4.89 gears. 11R22.5 Michelins at 105 and 95 PSI. Towing a Honda CRV. Air
filter has about 5000 miles. The air intake is the enlarged version designed
for the 250HP turbo engine. Never blows any black unless I make an operator
error.

To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate would
need to be off by almost 700 miles, or the fill-up would need to be off by
almost 70 gallons.

I'd be interested any anyone else's MPG observations and the method used.

Bob Griesel '84 FC31 WLII WA

[Dorn Hetzel]

I get between 9 and 10 mpg with my 77FC35, but we don't tow anything.  That was measured over a 5000 mile round trip to AZ from GA with side trips last year.  Our average speed (by GPS) was around 62.  Top speed around 72 on flat stretches with a tail wind

So 6-ish towing something doesn't sound completely unreasonable.

Dorn Hetzel

77FC35

Hogansville, GA

On Fri, Feb 12, 2010 at 3:17 PM, freewill2008 <"sundance101@comcast.net"> wrote:

 

Finally, after 7 years, I filled the fuel tank to the top, drove 1015 miles, and filled it again. The 167 gallons calculates to about 6 MPG.



The method has plenty of potential for error. The odometer reads low and I don't have a GPS. I used the Google mileage plus 5% to account for wrong turns, finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and Malibu, CA.



The tank is so big that I figure the fill could be off by as much as 10%. If the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were 10% high, the MPG would have been about 5.5.



Other details: 1984 FC31 with California 210HP turbo 3208. Road speed about 58 MPH. 4.89 gears. 11R22.5 Michelins at 105 and 95 PSI. Towing a Honda CRV. Air filter has about 5000 miles. The air intake is the enlarged version designed for the 250HP turbo engine. Never blows any black unless I make an operator error.



To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate would need to be off by almost 700 miles, or the fill-up would need to be off by almost 70 gallons.



I'd be interested any anyone else's MPG observations and the method used.



Bob Griesel '84 FC31 WLII WA

[Chuck Wheeler]

Bob,

Our 82 has averaged 9.2 on a little over
27,000 miles we have run without the diesel generator. It is non-turbo
210hp. We never tow and I usually have the cruse set on 60. Here in
the middle of the country it is a lot flatter than where you are. I use
the GPS and speedometer for mileage and they are usually within a couple of
tenths. Individual fill ups have been between about 7 and 11 mpg so I don’t
pay much attention to one tank. Most of this time it had Dunlop tires on
it at 115 on the front and 100 on the duals. (I raised the pressure after
weighing)

Two years ago I drove a 77 Eagle
entertainers coach from Bremerton WA to Denton
TX for a friend and used 202
gallons to cover 2211 miles at what ever the prevailing speed limit was.
It was a 6V71 with manual 4speed and a splitter. Been jealous of him ever
since.

- Chuck
Wheeler-

1982 FC 31SB Fort Worth TX

---

From:
WanderlodgeForum@yahoogroups.com [mailto:WanderlodgeForum@yahoogroups.com] On Behalf Of freewill2008

Sent: Friday, February 12, 2010
2:17 PM

To:
WanderlodgeForum@yahoogroups.com

Subject: [WanderlodgeForum] MPG
Reality Check

Finally, after 7 years, I filled the fuel tank to the
top, drove 1015 miles, and filled it again. The 167 gallons calculates to about
6 MPG.



The method has plenty of potential for error. The odometer reads low and I
don't have a GPS. I used the Google mileage plus 5% to account for wrong turns,
finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and Malibu, CA.



The tank is so big that I figure the fill could be off by as much as 10%. If
the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were 10%
high, the MPG would have been about 5.5.



Other details: 1984 FC31 with California
210HP turbo 3208. Road speed about 58 MPH. 4.89 gears. 11R22.5 Michelins at 105
and 95 PSI. Towing a Honda CRV. Air filter has about 5000 miles. The air intake
is the enlarged version designed for the 250HP turbo engine. Never blows any
black unless I make an operator error.



To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate would
need to be off by almost 700 miles, or the fill-up would need to be off by
almost 70 gallons.



I'd be interested any anyone else's MPG observations and the method used.



Bob Griesel '84 FC31 WLII WA

[Pete Masterson]

Considering the topography of your route, that's a trifle low for your 'bird, but not entirely out of line.

My 42' got a low of 4.5 and a high of more than 7 mpg. I noticed that the "best" fuel economy all happened east of the Rockies while traveling in flat places like Texas, Kansas, etc. FWIW, I used 5 mpg for planning purposes and generally got between 5 and 6 on most fill-ups. Hot temperatures (running the generator and ACs), mountains, and high speeds brought the mileage down. Cooler weather, flatter routes, and slower speeds all tended to bring the mileage up.

During the time I owned my coach, I did notice that filling the tank could be highly variable. If the fuel was more "foamy" I might get indications the (300 gal capacity) tank was full when it still could take 30 or 40 gallons more. If the fuel was less foamy, I'd get a much better fill up.

Often, if I'd wait a couple minutes while the fuel "settled down", I could add 20-30 more gallons. So, all the single-tank figures weren't terribly accurate. However, figuring the fuel used over a 2-1/2 year period and 20,000 miles, I ended up with an estimated 5.5 mpg including use of the AquaHot diesel burner (zero mpg) and the generator. The previous owner had calculated the operating hours of these units and had a "pure" mpg figure that put the efficiency nearer to 6+ mpg.

Your rig _should_ be getting something like 7 to 10 mpg if everything was well adjusted and the odometer readings were near-correct.

Pete Masterson

(former) '95 Blue Bird Wanderlodge WBDA 42

El Sobrante CA

"aeonix1@mac.com"

On Feb 12, 2010, at 12:17 PM, freewill2008 wrote:

Finally, after 7 years, I filled the fuel tank to the top, drove 1015 miles, and filled it again. The 167 gallons calculates to about 6 MPG.

The method has plenty of potential for error. The odometer reads low and I don't have a GPS. I used the Google mileage plus 5% to account for wrong turns, finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and Malibu, CA.

The tank is so big that I figure the fill could be off by as much as 10%. If the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were 10% high, the MPG would have been about 5.5.

Other details: 1984 FC31 with California 210HP turbo 3208. Road speed about 58 MPH. 4.89 gears. 11R22.5 Michelins at 105 and 95 PSI. Towing a Honda CRV. Air filter has about 5000 miles. The air intake is the enlarged version designed for the 250HP turbo engine. Never blows any black unless I make an operator error.

To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate would need to be off by almost 700 miles, or the fill-up would need to be off by almost 70 gallons.

I'd be interested any anyone else's MPG observations and the method used.

Bob Griesel '84 FC31 WLII WA

[mbulriss]

Bob says he is running 4.89 rear gears. Those are some real 'stump pulling' or
drag racing gears. It makes me wonder what rear gears are Dorn and Chuck
running that get 9-10MPG?

Mike Bulriss
1991 WB40 "Texas Minivan" - unknown rear gears
San Antonio, TX - finally sunny again!

--- In WanderlodgeForum@yahoogroups.com, "freewill2008" wrote:
>
> Finally, after 7 years, I filled the fuel tank to the top, drove 1015 miles,
and filled it again. The 167 gallons calculates to about 6 MPG.
>
> The method has plenty of potential for error. The odometer reads low and I
don't have a GPS. I used the Google mileage plus 5% to account for wrong turns,
finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and
Malibu, CA.
>
> The tank is so big that I figure the fill could be off by as much as 10%. If
the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were 10%
high, the MPG would have been about 5.5.
>
> Other details: 1984 FC31 with California 210HP turbo 3208. Road speed about
58 MPH. 4.89 gears. 11R22.5 Michelins at 105 and 95 PSI. Towing a Honda CRV.
Air filter has about 5000 miles. The air intake is the enlarged version
designed for the 250HP turbo engine. Never blows any black unless I make an
operator error.
>
> To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate
would need to be off by almost 700 miles, or the fill-up would need to be off by
almost 70 gallons.
>
> I'd be interested any anyone else's MPG observations and the method used.
>
> Bob Griesel '84 FC31 WLII WA
>

[Dorn Hetzel]

I don't actually know what gears I have.   I do know the previous owner re-rimmed it so it runs all standard 11r22.5 truck tires but I don't know if that diameter varies from the original substantially.

dorn hetzel

77fc35

Hogansville, ga

On Feb 12, 2010 6:55 PM, "mbulriss" <"mbulriss@yahoo.com"> wrote:

 

Bob says he is running 4.89 rear gears. Those are some real 'stump pulling' or drag racing gears. It makes me wonder what rear gears are Dorn and Chuck running that get 9-10MPG?



Mike Bulriss

1991 WB40 "Texas Minivan" - unknown rear gears

San Antonio, TX - finally sunny again!



--- In "WanderlodgeForum@yahoogroups.com", "freewill2008" wrote:

>
> Finally, afte...

[Chuck Wheeler]

Ours was 5.29 I changed it to 4.89 about
four years ago. “Sweet spot” moved from about 57 to 62.

- Chuck
Wheeler-

1982 FC 31SB Fort Worth TX

---

From:
WanderlodgeForum@yahoogroups.com [mailto:WanderlodgeForum@yahoogroups.com] On Behalf Of Dorn Hetzel

Sent: Friday, February 12, 2010
6:12 PM

To:
WanderlodgeForum@yahoogroups.com

Subject: Re: [WanderlodgeForum]
Re: MPG Reality Check

I don't
actually know what gears I have. I do know the previous owner
re-rimmed it so it runs all standard 11r22.5 truck tires but I don't know if
that diameter varies from the original substantially.

dorn hetzel

77fc35

Hogansville, ga

On Feb 12, 2010 6:55 PM,
"mbulriss" <"mbulriss@yahoo.com">
wrote:

Bob says he is running 4.89 rear gears. Those are some
real 'stump pulling' or drag racing gears. It makes me wonder what rear gears
are Dorn and Chuck running that get 9-10MPG?



Mike Bulriss

1991 WB40 "Texas Minivan" - unknown rear gears

San Antonio, TX - finally sunny again!

--- In "WanderlodgeForum@yahoogroups.com",
"freewill2008" ...> wrote:

>

> Finally, afte...

[jackcj7]

Hardly in the same league as the "Deezel" birds, but the mileage in our 1973FC31
with the 391 gas engine bounces around between 5 & 6mpg... This is making the
loop from SoCal to the Seattle area, over to Spokane and Billings, and home
through either Denver or Salt Lake City... We always tow our CJ7 fitted with
freewheeling hubs at all corners... Most of the time, we can roll along at 60,
but on some hills a bit slower. On the Grapevine and Raton quite a bit slower,
more like 18 to 20...Just find a big, slow 18 wheeler and fall in behind him...
Jack Smith
1973FC31
SoCal
.
--- In WanderlodgeForum@yahoogroups.com, "freewill2008" wrote:
>
> Finally, after 7 years, I filled the fuel tank to the top, drove 1015 miles,
and filled it again. The 167 gallons calculates to about 6 MPG.
>
> The method has plenty of potential for error. The odometer reads low and I
don't have a GPS. I used the Google mileage plus 5% to account for wrong turns,
finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and
Malibu, CA.
>
> The tank is so big that I figure the fill could be off by as much as 10%. If
the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were 10%
high, the MPG would have been about 5.5.
>
> Other details: 1984 FC31 with California 210HP turbo 3208. Road speed about
58 MPH. 4.89 gears. 11R22.5 Michelins at 105 and 95 PSI. Towing a Honda CRV.
Air filter has about 5000 miles. The air intake is the enlarged version
designed for the 250HP turbo engine. Never blows any black unless I make an
operator error.
>
> To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate
would need to be off by almost 700 miles, or the fill-up would need to be off by
almost 70 gallons.
>
> I'd be interested any anyone else's MPG observations and the method used.
>
> Bob Griesel '84 FC31 WLII WA
>

[Michael]

--- In WanderlodgeForum@yahoogroups.com, "jackcj7" wrote:
>
>
> Hardly in the same league as the "Deezel" birds, but the mileage in our
1973FC31 with the 391 gas engine bounces around between 5 & 6mpg... This is
making the loop from SoCal to the Seattle area, over to Spokane and Billings,
and home through either Denver or Salt Lake City... We always tow our CJ7
fitted with freewheeling hubs at all corners... Most of the time, we can roll
along at 60, but on some hills a bit slower. On the Grapevine and Raton quite a
bit slower, more like 18 to 20...Just find a big, slow 18 wheeler and fall in
behind him...
> Jack Smith
> 1973FC31
> SoCal
> .
> --- In WanderlodgeForum@yahoogroups.com, "freewill2008" wrote:
> >
> > Finally, after 7 years, I filled the fuel tank to the top, drove 1015 miles,
and filled it again. The 167 gallons calculates to about 6 MPG.
> >
> > The method has plenty of potential for error. The odometer reads low and I
don't have a GPS. I used the Google mileage plus 5% to account for wrong turns,
finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and
Malibu, CA.
> >
> > The tank is so big that I figure the fill could be off by as much as 10%.
If the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were
10% high, the MPG would have been about 5.5.
> >
> > Other details: 1984 FC31 with California 210HP turbo 3208. Road speed
about 58 MPH. 4.89 gears. 11R22.5 Michelins at 105 and 95 PSI. Towing a Honda
CRV. Air filter has about 5000 miles. The air intake is the enlarged version
designed for the 250HP turbo engine. Never blows any black unless I make an
operator error.
> >
> > To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate
would need to be off by almost 700 miles, or the fill-up would need to be off by
almost 70 gallons.
> >
> > I'd be interested any anyone else's MPG observations and the method used.
> >
> > Bob Griesel '84 FC31 WLII WA
> >
> Do the calcs when home from a trip, fill @ the same pump @ local truck stop,
add up all the fuel used and divide by miles traveled. My FC w/charge air
cooler gets 6.5/7.0 every time. Odo verified by mile sticks. Do the whole trip
average as that's the best way to figure real mileage. Cruise @ 63 most of the
time. Tow 240D or F-150.

[ebirder2000@...]

Bob, I don't dispute your method or your finding at all. My only comment is, that mileage seems too low.I would expect thatyour mileage would be closer to 8mg. But,that's only based on other folks bragging including my own,that I have observed.

Steve (at Painted Rocks campground). Temp 80 degrees with absolute clear blue skies.

In a message dated 2/12/2010 12:22:01 P.M. Pacific Standard Time, sundance101@... writes:

Finally, after 7 years, I filled the fuel tank to the top, drove 1015 miles, and filled it again. The 167 gallons calculates to about 6 MPG.

The method has plenty of potential for error. The odometer reads low and I don't have a GPS. I used the Google mileage plus 5% to account for wrong turns, finding RV sites, etc. The route was Brookings, OR to Q by way of Hwy 101 and Malibu, CA.

The tank is so big that I figure the fill could be off by as much as 10%. If the fill-up were 10% low, the MPG would have been 6.7. If the fill-up were 10% high, the MPG would have been about 5.5.

Other details: 1984 FC31 with California 210HP turbo 3208. Road speed about 58 MPH. 4.89 gears. 11R22.5 Michelins at 105 and 95 PSI. Towing a Honda CRV. Air filter has about 5000 miles. The air intake is the enlarged version designed for the 250HP turbo engine. Never blows any black unless I make an operator error.

To achieve the 10 MPG sometimes suggested for the FC, my mileage estimate would need to be off by almost 700 miles, or the fill-up would need to be off by almost 70 gallons.

I'd be interested any anyone else's MPG observations and the method used.

Bob Griesel '84 FC31 WLII WA