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.
  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 07-27-2016, 07:27 PM   #15
Senior Member
Join Date: Feb 2006
Location: NW Arkansas
Posts: 126
I have a Scan Gauge and watch the boost reading. The higher the boost the more fuel I am burning.

Unless I have a need to be somewhere at a certain time, 67 MPH with no headwind is the sweet spot for my Cummins.

JumboJet 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 07-27-2016, 10:02 PM   #16
Senior Member
TonyDi's Avatar

Join Date: Feb 2011
Location: Point Pleasant Beach, NJ
Posts: 11,758
Minimize weight. Avoid full H2O tank unless necessary. Remove anything hat is dead weight and seldom used. Under-inflated tires on the MH and the toad don't roll well so make sure they are at the correct pressures.
Plus the above!

Tony & Ruth........... FMCA#F416727
Newmar Dutch Star 4320, Spartan MM Chassis, Cat C9, Jeep Grand Cherokee Hemi, Blue Ox Aventa LX, and Brake Buddy. TST 507 TPMS
TonyDi is online now   Reply With Quote
Old 07-27-2016, 11:15 PM   #17
Senior Member
rgvtexan's Avatar
Winnebago Owners Club
Freightliner Owners Club
Join Date: Oct 2009
Location: NE WA or S TX
Posts: 2,429
A rubber ducky with a squeaker! Put it behind the petal, if it squeaks when you push, back off and push slower. Drivers ED 1957.
04 Horizon QD, 12 Ford Flex, Excalibar, Brakemaster, Winter Texan, RVin! since 1974
Norm, Donna & Tinker Kat 74 MGB-GT, 75 MGB, 01 Z3
Life is a Timed Event, you only get One Go Around!
rgvtexan is offline   Reply With Quote
Old 07-27-2016, 11:46 PM   #18
ultra's Avatar
Monaco Owners Club
Join Date: Oct 2014
Location: Parker, CO
Posts: 88
Originally Posted by Stealth01 View Post
In addition to the above, find your "cruise sweet spot", on our Cummins 500 ISM it's ~1,350 RPM @ ~61 MPH. Engage the "Mode" switch on your transmission selector panel and maximize the use of cruise control.
What is the purpose of the "Mode" button on the transmission selector?
Jim & Anna
42' 2007 Monaco Camelot, PDQ, ISL 400
ultra is offline   Reply With Quote
Old 07-28-2016, 06:51 AM   #19
Community Moderator
barmcd's Avatar

Monaco Owners Club
Texas Boomers Club
Join Date: Nov 2015
Location: Central Texas
Posts: 5,395
It doesn't seem like anything I do makes an appreciable difference in mileage except driving slower.
Dennis and Katherine
2000 Monaco Dynasty
barmcd is offline   Reply With Quote
Old 07-29-2016, 12:54 AM   #20
Senior Member
DD788Snipe's Avatar

Newmar Owners Club
Spartan Chassis
Join Date: Jun 2013
Location: Apple Valley CA
Posts: 922
Originally Posted by DGBPokes View Post
Sounds good to me....how do I find the " sweet spot" on a Cummins 350 ISL
The sweet spot on your rig is 62 mph @ 1800 rpm. I get around 8.5 to 9 mpg in that range and drive with my cruise control except when I'm in city traffic. I did have my ECM reflashed to increase the HP and torque. That helped pull the grades better but I still get about the same mpg as when I had 350 HP. My torque went from 1050 ft/lbs to 1200ft/lbs. that was the difference.

Craig & Carolyn Roberts Apple Valley, CA
2006 Newmar 3910 KSDP 400 ISL Cummins Spartan Mountian Master Chassis
Toad: 2017 GMC Canyon 4X4 Crewcab
DD788Snipe is offline   Reply With Quote
Old 07-29-2016, 04:33 AM   #21
Senior Member
spsm's Avatar
Join Date: Oct 2013
Posts: 680
Hypermiling....................try it sometime.
spsm is offline   Reply With Quote
Old 07-29-2016, 06:44 AM   #22
Senior Member
VSPA's Avatar
Winnebago Owners Club
Ford Super Duty Owner
Join Date: Jul 2011
Location: Humble/Atascocita, Texas
Posts: 1,246
Often discussed subject and I read through them every time I see one. We've a 2014 Itasca 35F and the only time I checked the mileage on it was during the 2500 mile round trip of our maiden voyage towing the wife's Focus on a dolly. Got 7.5 mpg. I use most of the suggestion above that will apply to a V10 gasser, but the things I have found that gives the best results and feeling of road safety is using the cruise control and keep it at 55-60 (mile per minute) or below and accelerate at a moderate pace and I keep a pancake compressor in a storage bin and check the tire pressure prior to each trip. Also, approximately every 2.5k miles I'll add a couple of bottles of Lucas fuel injection cleaner. Even at that I don't think I will ever get up to the 16-18 mpg that I got out of our first RV, a 1987 Toyota Dolphin. Comfort does have it costs.
Stan, Shirley & 2 Schnauzers (Sandy & Sassy)
RV: 2014 Itasca Sunstar 35F
USAF, Retired, Life Member: DAV, VFW, VVA, & VSPA
VSPA is online now   Reply With Quote
Old 07-29-2016, 07:02 AM   #23
Senior Member
Join Date: Jan 2009
Posts: 1,121
Originally Posted by barmcd View Post
It doesn't seem like anything I do makes an appreciable difference in mileage except driving slower.
This is our experience as well. Hard stops and quick take offs do use more fuel but the big thing is driving anything over 65. Haven't plugged the scan gauge into the MH but for grins, i think i'll do that the next time we're on a trip. For now, around 55 seems to be good with us getting a bit over 9 on relatively flat ground with no toad.
03 Itasca Sunova, 8.1 Workhorse on a P32 chassis
Mudfrog is offline   Reply With Quote
Old 07-29-2016, 08:13 AM   #24
Crossingover's Avatar
Join Date: Aug 2015
Posts: 87
Above about 50 mph overcoming aerodynamic drag consumes more engine power to push forward so I'm waiting to see someone market an RV air tab kit similar to the air tabs you see on some tractor trailers (e.g., beneath the trailer and around the rear doors). I'm sure some of the aero research and devices for tractor trailers would apply to MHs with the corresponding savings in fuel.
Rick with Lori, Two Pekes and a Shih Tzu
16 Jayco Seneca 37HJ : Freightliner M2
16 Jeep Sahara Ultimate : Blackhawk tether
Crossingover is offline   Reply With Quote
Old 07-29-2016, 08:24 AM   #25
Registered User
mel s's Avatar
Join Date: Mar 2010
Posts: 8,777
Originally Posted by DGBPokes View Post
Sounds good to me....how do I find the " sweet spot" on a Cummins 350 ISL
Call Cummins Care at 1-800-343-7357 with your engine serial number and ask...(nobody knows more about your particular Cummins engine than Cimmins Inc.).
'96 Safari
mel s is offline   Reply With Quote
Old 07-29-2016, 09:53 AM   #26
Senior Member
Join Date: Jul 2015
Location: Watertown NY USA
Posts: 1,484
I use my cruise control quite a bit but when I see a long grade coming up I disengage the cruise, accelerate slightly and let off the throttle as necessary to maintain a reasonable speed without the transmission shifting down too many gears and allowing the RPM to rise sharply.
I do the same when driving a truck with a heavy load or towing a trailer.
I stay to the right so I don't stall traffic out behind me.
2002 Fleetwood Storm 30H on Workhorse P32 chassis 8.1 gas.
LETMGROW is offline   Reply With Quote
Old 07-29-2016, 10:34 AM   #27
Senior Member
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 1,964
I have tried and used all of the already mentioned practices. I have found that on a long trip, the rate of acceleration has little effect on the overall economy. Probably because there is so little time over the course of a day that the coach is acceleration mode. At the end of the day, I doubt that the difference between getting up to speed fast or slow can be measured in overall fuel consumption. The things that work for me are a steady moderate speed of 62 mph, (55 is better, but I just can't drive that speed for 10 hours), proper tire inflation, slowing and coasting to a stop rather than braking, avoid days with strong head winds, (there is always a head wind, but some are stronger than others), and not letting the engine idle longer that it takes to get air pressure up. I also shut the engine down as soon as I get to my stop. At 50,000# total weight, Removing 1000# of water and unneeded items won't make a difference, so I go with whatever we have at the time.

If fuel efficiency were my top priority, I would be driving a small class B van conversion with a Mercedes diesel getting 20 mpg instead of 7. But then I would have to make too many trips to take everything.
2013 43 QGP Allegro Bus
2013 Avalanche
Stretched LJ Rock Crawler
Crasher is offline   Reply With Quote
Old 07-29-2016, 08:21 PM   #28
Senior Member
Coma's Avatar
Monaco Owners Club
Join Date: Nov 2010
Location: The Emerald Coast
Posts: 1,757
As a general rule you will obtain your best mpg at a couple hundred rpm above torque peak, assuming you have enough horsepower in your highest gear to do that. On the same vehicle worst operator to best operator can vary as much as a 30%.

Jim and Jennie, Cats=Bittles and Potter, 2000 Dynasty 350 ISC
2013 Silverado 4x4 Towed with R1200GS in bed.
PROV23:4 Do not wear yourself out to get rich; have the wisdom to show restraint.
Coma is offline   Reply With Quote


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
A Good Experience w/Progressive Following Accident RickO iRV2.com General Discussion 22 12-13-2012 06:18 AM
Warning Code 278 following lift pump replacement Catch14me Cummins Engines 3 04-07-2011 11:05 PM
What 'should' I expect to pay for the following services in Oregon...: fkloster MH-General Discussions & Problems 1 08-20-2010 11:14 AM
Can a pill save you fuel or just another gimmick? Warpath iRV2.com General Discussion 4 03-22-2006 05:37 AM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 07:30 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.