Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 08-18-2016, 08:05 PM   #29
Senior Member
 
Join Date: Nov 2006
Location: Centerville, Iowa
Posts: 241
Sweet Spot and Trucker's Rule

Every diesel has a sweet spot, where torque and performance is maximized. Manufacturers have that information on their websites. The last semi tractor I owned it was 1825 rpm. If I drove at that rpm everything was maxed out.

The general rule of thumb is for every 1 mph over the sweet spot, you lose .1 mpg So if 62 mph is the sweet spot, at 72 mph you would lose .1 x 10 equals 1 mpg. It will generally work that way.

I have a 1999 American Eagle and pull an 20 foot enclosed trailer with a Model T in it. I drove from Iowa to Albuqurque with a 35 mph head wind all the way. Averaged 6.5 mpg. Coming back I had the same wind, only it was a tail wind and averaged 9 mpg. Generally I figure 7 to 7.5. Cummins ISC 350 horse power.
__________________

__________________
Mike Thomas is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 08-19-2016, 06:47 AM   #30
Senior Member
 
Fiesta48's Avatar
 
Fleetwood Owners Club
Freightliner Owners Club
Join Date: Nov 2010
Location: Texas
Posts: 953
05 V10 9.0 mpg, 11 V10 8.0 mpg (heavier, no car), 15 ISL diesel 8.9L 9.0 mpg (50% heavier, & pulling a car), but much more relaxed. Retired, I drive sanely, why rush?
__________________

__________________
Full Timers.
2015 Fleetwood Discovery 40E on a Freightliner XCS chassis with a Cummins ISL9 pulling 1 and/or 2 motorcycles, '07 Honda Accord OR a 17' Runabout Boat.
Fiesta48 is offline   Reply With Quote
Old 08-19-2016, 09:34 AM   #31
Senior Member
 
VestaDave's Avatar
 
Join Date: Nov 2011
Posts: 644
Quote:
Originally Posted by RickyM View Post
My wife and I just recently bought a new 2016 fleetwood pace arrow 38 ft with 340hp 6.7L isb cummins motor. We just got back from a 2 wek trip to NH and ME. Over 1000 miles there and back towing a jeep Cherokee. We averaged 9 mpg with average speed of 65 mph . I really expected better fuel economy, with all the new requirements on emissions. I understand it's a big square box on 6 wheels but with all the technology out there it seems that these engines should get better fuel economy.

Don't get me wrong I absolutely love our new motorhome but I would like to get better fuel mileage then 9 mpg.

I'm going to guess that this comment is "tongue in cheek". Judging by all the other entries here 9 mpg is not only good , it's awesome!! Given your ave. speed, weight and tow you should be less mpg.
__________________
VestaDave is offline   Reply With Quote
Old 08-19-2016, 10:43 AM   #32
Senior Member
 
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 1,176
When we travel from WI to AZ in the fall, I stop twice for fuel. If I had a gas coach, I would have to stop four times and make two trips to get everything there, so I guess the diesel gets better milage.
__________________
2013 43 QGP Allegro Bus
Crasher is offline   Reply With Quote
Old 08-22-2016, 09:31 PM   #33
Senior Member
 
TBS-POPS's Avatar
 
Join Date: Nov 2013
Location: Valley Springs, Ca
Posts: 317
8 with a head wind, 12 with a tail wind . Usually fall in the 9-10 range. ISC 330.
__________________
2004 Holiday Rambler Endeavor "The scooter II"
TBS-POPS is offline   Reply With Quote
Old 08-23-2016, 08:31 PM   #34
Senior Member
 
Rich-n-Linda's Avatar
 
Join Date: Nov 2011
Posts: 884
Expected fuel mileage for a Diesel Motorhome

Quote:
Originally Posted by RickyM View Post
...Don't get me wrong I absolutely love our new motorhome but I would like to get better fuel mileage then 9 mpg.

LOL!! Dream on...it will never get any better than that.

At 9 mpg you are already slightly above average.
__________________
Rich-n-Linda is offline   Reply With Quote
Old 08-23-2016, 09:03 PM   #35
Senior Member
 
Steve Ownby's Avatar
 
Join Date: Nov 2008
Location: Cosby, Tn
Posts: 5,963
Quote:
Originally Posted by RickyM View Post
My wife and I just recently bought a new 2016 fleetwood pace arrow 38 ft with 340hp 6.7L isb cummins motor. We just got back from a 2 wek trip to NH and ME. Over 1000 miles there and back towing a jeep Cherokee. We averaged 9 mpg with average speed of 65 mph . I really expected better fuel economy, with all the new requirements on emissions. I understand it's a big square box on 6 wheels but with all the technology out there it seems that these engines should get better fuel economy.

Don't get me wrong I absolutely love our new motorhome but I would like to get better fuel mileage then 9 mpg.

The emissions requirements are a story of diminishing returns. The computer controls that run Diesel engines now are so precise that I'm guessing all the emissions specific hardware could be removed and they would still be pretty clean. The hardware required to meet emissions standards do nothing to enhance economy. The worst system for economy is the EGR system which was the first requirement. The addition of the DEF system on 2010 and later engines actually resulted in some economy and power gains because the EGR could be de tuned somewhat. Your ISB engine has long been an economy champ in motorhome service. 9 mpg is pretty good. If you are willing to slow down to 60, you will pick up some more mileage.
__________________
Steve Ownby
Full time since 2007
2003 Monaco Signature
Steve Ownby is offline   Reply With Quote
Old 08-23-2016, 09:14 PM   #36
Senior Member
 
Scottybdivin's Avatar


 
Newmar Owners Club
Join Date: Jun 2012
Location: Spicewood Texas (West of Austin)
Posts: 3,067
6.5 average for my Cummins ISM 450 towing the F150 65 MPH. Total weight is about 49K.
__________________
Scotty and Kristen, Airedales Dagny and Wyatt
2007 Newmar Mountain Aire 4528, 450 HP ISM, Allison 4000, 8 Trojan T-105's
2014 F150 4x4 Crew Cab Platinum 157" WB
Roadmaster Blackhawk 2, RVI2 Brake System
Scottybdivin is offline   Reply With Quote
Old 08-23-2016, 09:29 PM   #37
Member
 
Spizzer's Avatar
 
Join Date: Sep 2013
Posts: 97
We run a 34ft with a Cat C7 towing a Jeep Grand Cherokee. If I drive 62-63 mph I get around 8.7 mpg. Fighting winds I'll get 7.5. Interestingly, when we were driving across the causeway in Louisiana, it is flat, and there was no wind. I set the cruise on 55 mph and the computer settled in on 10mpg. Bumped it up to 60 mph and it was 9 mpg. 65 mph gave me 8 mpg, and you guessed it, 70 mph was 7 mpg.

As a side note, driving 62 mph I find myself much more relaxed than even 65. Driving is a pleasure, and I'm not exhausted at the end of the day.

Jeff
__________________
Spizzer is offline   Reply With Quote
Old 08-23-2016, 09:45 PM   #38
Member
 
dubbyjig's Avatar
 
Monaco Owners Club
Join Date: Dec 2010
Location: Auburn, WA
Posts: 63
Our most recent trip we got 9.7 mpg
ISB 275 hp

Around 33,000 lbs

Try to keep it at 65 mph
__________________

__________________
Bill & Gabrielle
1999 Monaco Diplomat 38A
dubbyjig is offline   Reply With Quote
Reply

Tags
diesel, fuel, motorhome



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Bounder: Expected Gas Mileage Bounder3View Fleetwood Products Owner's Forum 31 05-12-2015 07:52 AM
Expected Mileage Bompa13 Fleetwood Products Owner's Forum 5 10-09-2014 03:45 PM
Expected mileage from a 1989 Southwind 33ft cubman Fleetwood Products Owner's Forum 10 07-17-2009 08:10 PM
Expected Mileage JavaJelly Newmar Owner's Forum 4 01-03-2007 12:10 PM

» Virginia Campgrounds

Reviews provided by

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 03:05 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.