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[GMCnet] What MPG do these GMC's get? [message #275947] Wed, 15 April 2015 21:19 Go to next message
BobDunahugh is currently offline  BobDunahugh   United States
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Registered: October 2010
Location: Cedar Rapids, IA
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Senior Member



There are so many variables that enter into this question. Condition of the coach, and most importantly driving habits. The only way to get proper data. Is on trips of 2000 miles, and more to get good in put. If you could always just get the tanks really full to the same level each time. The trip to Patterson was a good chance to gather good data. Not home yet. But we're now at 2752 miles. Iowa, to Patterson, and now in Minnesota. And see how well I could do by just paying attention to my driving habits. There is one external element that did help. We live at 816 ft above sea level. Most of the trip was fairly flat. 78 Royale. 403, 3.70 final drive, completely stock exhaust, and carb. 12,273 lbs. Handicapped equipped 08 Chevy Uplander with dolly. 5,751 lbs. Gross weight. 18,024 lbs. Used the new cruise from Jim K as much as possible. Had it off in the hilly areas that we did encounter. Kept speed around 60 MPH. EZ on starts, and stops. So, 273 gallons for the 2752 miles c
ame to 10.1 MPG at the last fill. This has been the best I've ever done. I do know that the 3.70 final drive has paid off. And the vacuum gauge. I had a .7 MPG when I installed both. I now have my EFI with spark control to install. I'm hoping that the spark control part will help with MPG. That's next. Bob Dunahugh Member GMCMI

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Re: [GMCnet] What MPG do these GMC's get? [message #275962 is a reply to message #275947] Thu, 16 April 2015 08:49 Go to previous messageGo to next message
thesmith is currently offline  thesmith   United States
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Registered: February 2015
Location: Cary, NC
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Which is not too bad.....Back in the 80's I did about 3000 miles in a 22ft Class A Winnebago (5.7 liter Chevy V8 gas IIRC) around the Rockies from Denver down to Monument valley and up to Montana) and it got only 5-8 MPG, 5 up mountains 8 on the flat.....of course then I had a lead foot and thought US gas was just so cheap!.

Gas is about the same cost now in real terms (maybe even cheaper) so 9-10 would be fine with me.


Pete


Cary, NC 1978 Center Kitchen Royale.
Re: [GMCnet] What MPG do these GMC's get? [message #275964 is a reply to message #275947] Thu, 16 April 2015 09:43 Go to previous messageGo to next message
Jim Galbavy is currently offline  Jim Galbavy   United States
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Registered: August 2007
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Bob,

Add in another variable, fuel. My first tanks leaving Lake Mary, Fl were full
of none ethanol 92 octane gas and got 10.7 mpg driving 66-67 mph. I have a
stock 307 diff. By the time I got to Patterson it was down to 8.5 mpg doing the
same speeds over the same types of roads, but having to fuel up with ethanol laced
mogas.

jwid

jim galbavy
'73 x-CL ANNIE
LAKE MARY, FL
Re: [GMCnet] What MPG do these GMC's get? [message #276007 is a reply to message #275947] Thu, 16 April 2015 23:04 Go to previous messageGo to next message
BobDunahugh is currently offline  BobDunahugh   United States
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Registered: October 2010
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Senior Member
All the gas that was used on the trip to Patterson. And back to Iowa was 87 octane with ethanol. That is all I ever use. Bob Dunahugh

From: yenko108@hotmail.com
To: gmclist@temp.gmcnet.org
Subject: What MPG do these GMC's get?
Date: Wed, 15 Apr 2015 21:19:17 -0500







There are so many variables that enter into this question. Condition of the coach, and most importantly driving habits. The only way to get proper data. Is on trips of 2000 miles, and more to get good in put. If you could always just get the tanks really full to the same level each time. The trip to Patterson was a good chance to gather good data. Not home yet. But we're now at 2752 miles. Iowa, to Patterson, and now in Minnesota. And see how well I could do by just paying attention to my driving habits. There is one external element that did help. We live at 816 ft above sea level. Most of the trip was fairly flat. 78 Royale. 403, 3.70 final drive, completely stock exhaust, and carb. 12,273 lbs. Handicapped equipped 08 Chevy Uplander with dolly. 5,751 lbs. Gross weight. 18,024 lbs. Used the new cruise from Jim K as much as possible. Had it off in the hilly areas that we did encounter. Kept speed around 60 MPH. EZ on starts, and stops. So, 273 gallons for the 2752 miles c
ame to 10.1 MPG at the last fill. This has been the best I've ever done. I do know that the 3.70 final drive has paid off. And the vacuum gauge. I had a .7 MPG when I installed both. I now have my EFI with spark control to install. I'm hoping that the spark control part will help with MPG. That's next. Bob Dunahugh Member GMCMI

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Re: [GMCnet] What MPG do these GMC's get? [message #276059 is a reply to message #275947] Fri, 17 April 2015 12:08 Go to previous message
jhbridges is currently offline  jhbridges   United States
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Registered: May 2011
Location: Braselton ga
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I use non-ethanol unless I have to by laced gas. Patterson and back was all non-ethanol. Overall looks to be 10.07 with the MouseToad clipped on behind. 23' with the original 3:07 gearing, run right at 60 per on cruise for the bulk of the trip.
Past experience is, it gains nearly 1 MPG without the toad, but it's been a year since I went anyplace without one. Ethanol gas drops the mileage about 10%.

--johnny


Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell
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