RV Trip Planning Discussions

Go Back   iRV2 Forums > THE OWNER'S CORNER FORUMS > Newmar Owner's Forum
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 04-22-2017, 06:44 AM   #29
4x4
Senior Member
 
4x4's Avatar
 
Newmar Owners Club
Join Date: Dec 2014
Posts: 278
Oh yeah, my computer calculates .1 of a mile higher than the pencil calculation, when doing highway and when not using the Hydrohot but the generator was used for about an hour, so the Silverleaf computer was very accurate.
__________________

__________________
2007 Newmar Essex 4510, Spartan K2, 500HP ISM, Allison 4000
Silverleaf Dash & House, 1720w Solar, Dual Victron 3kw Multiplus, 1200ah Lithium
2016 Jeep Hard Rock Rubicon Wrangler Unlimited
4x4 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 04-25-2017, 06:01 AM   #30
Senior Member
 
SMertens's Avatar
 
Newmar Owners Club
Freightliner Owners Club
Join Date: Jul 2016
Posts: 115
So we have a 2016 DSDP with an Allison 3000 & Cummins ISL15 450HP. I have a motorcycle lift and flat tow a Jeep Cherokee. My sweet spot is about 68mph. That gets me in second Overdrive when cruising on the freeway. The minute I get off the freeway or in traffic I use the Mode button. This will lower your shift RPMs and keep you more fuel efficient, you will lose some power, so NEVER run this way up hill.

Bottom line is it will be a different sweet spot for engine/transmission combination. I can get over 8mpg depending on my drive type that day
__________________

SMertens is offline   Reply With Quote
Old 04-28-2017, 04:40 PM   #31
Member
 
Join Date: Apr 2013
Posts: 97
My 2008 All Star with a 400hp ISL and a CRV road gets about 7-7.5 on mostly flat ground at 65mph. Going above 65 drops the mileage dramatically.
Entropy is offline   Reply With Quote
Old 05-07-2017, 12:01 PM   #32
Senior Member
 
rlott2k's Avatar
 
Join Date: Aug 2013
Location: BC, Cariboo, Lower Mainland.
Posts: 1,323
Man, I seen to be 6.5 no matter what! I drive 60mph and get this figure off my dash gauge. I do know how to calculate on paper, but wonder if others do. I'd love to get 8.0!
__________________
2008 KSDP/2013 Flex
2nd year Fulltimers and still loving it.
rlott2k is offline   Reply With Quote
Old 05-07-2017, 12:22 PM   #33
Senior Member
 
SMertens's Avatar
 
Newmar Owners Club
Freightliner Owners Club
Join Date: Jul 2016
Posts: 115
Quote:
Originally Posted by rlott2k View Post
Man, I seen to be 6.5 no matter what! I drive 60mph and get this figure off my dash gauge. I do know how to calculate on paper, but wonder if others do. I'd love to get 8.0!
AS far as calculating MPG, its easy. Fill up the tank, write down your mileage. Drive until the next fill up, write down the number of gallons you took and the number of miles on odometer now. Now divide totals miles you drove by number of gallons you used. Or simply get an app for a smartphone like "MileageKeeper" Personally I use my RV Pilot fuel card, and all I have to do is write down miles at fill up. I can always go back to My Pilot and get gallons for both fuel and DEF.

BTW Slower on the freeway is not necessarily better, you have to know the sweet spot for your engine where it is its most fuel efficient. What engine/trans do you have?
SMertens is offline   Reply With Quote
Old 05-07-2017, 01:32 PM   #34
Senior Member
 
rlott2k's Avatar
 
Join Date: Aug 2013
Location: BC, Cariboo, Lower Mainland.
Posts: 1,323
Quote:
Originally Posted by SMertens View Post
AS far as calculating MPG, its easy. Fill up the tank, write down your mileage. Drive until the next fill up, write down the number of gallons you took and the number of miles on odometer now. Now divide totals miles you drove by number of gallons you used. Or simply get an app for a smartphone like "MileageKeeper" Personally I use my RV Pilot fuel card, and all I have to do is write down miles at fill up. I can always go back to My Pilot and get gallons for both fuel and DEF.

BTW Slower on the freeway is not necessarily better, you have to know the sweet spot for your engine where it is its most fuel efficient. What engine/trans do you have?
Yes, I'm aware how to calculate, I'd like to know if others do the same.( use the dash gauge for their #s) I have a 400 isl Cummins. Tire pressure is correct for weight. Maybe I'll try some diesel fuel additive. It would be a good idea to put pen to paper to check also, although pump shut off points, foaming etc can also throw the math out.
__________________
2008 KSDP/2013 Flex
2nd year Fulltimers and still loving it.
rlott2k is offline   Reply With Quote
Old 05-07-2017, 02:30 PM   #35
Senior Member
 
SMertens's Avatar
 
Newmar Owners Club
Freightliner Owners Club
Join Date: Jul 2016
Posts: 115
Quote:
Originally Posted by rlott2k View Post
Yes, I'm aware how to calculate, I'd like to know if others do the same.( use the dash gauge for their #s) I have a 400 isl Cummins. Tire pressure is correct for weight. Maybe I'll try some diesel fuel additive. It would be a good idea to put pen to paper to check also, although pump shut off points, foaming etc can also throw the math out.
Sorry, I read your post as NOT knowing how to calculate. My bad!

As far as adding Additive or anything else will not help you until you understand where the sweet spot is for your engine RPM's. For example my engine ISL 15/450 I get my best fuel mileage (a little over 8MPG) if shifting RMS's stay in the range of 1710-1800 and cruise around 67-68MPH in OD2.

I've heard others say for the 400,ISL they use 64-65, but this is from my memory, you should verify that. Also, most transmissions shift points are set up for power, not economy, this is why I use the "MODE" or Economy Mode on my transmission around town. This will keep your shift points in the lower, more economy range. You have to find put what RPM range is your most efficient for your engine and stay in that range as much as possible.

You may want to stop by a Cummins dealer or give them a call and ask where the most fuel efficient RPM range is for your engine. My guess is - if it's an ISL it will be in the range of 1710-1790.

No I never use the dash calculations, I gather mileage when I fuel and do those calcs myself. I keep a running spreadsheet with the averages. Additives won't do a thing for fuel mileage if you can't find the right RPM's. The time to add additives is when you are getting top MPG, and want that extra 1/10 gallon.
__________________
2016 DSDP 4018
2018 Dodge RAM 2500 Long Bed
2018 Polaris 900 Trail - In the RAM Bed
SMertens is offline   Reply With Quote
Old 05-08-2017, 08:49 AM   #36
Senior Member
 
rlott2k's Avatar
 
Join Date: Aug 2013
Location: BC, Cariboo, Lower Mainland.
Posts: 1,323
Quote:
Originally Posted by SMertens View Post
Sorry, I read your post as NOT knowing how to calculate. My bad!

As far as adding Additive or anything else will not help you until you understand where the sweet spot is for your engine RPM's. For example my engine ISL 15/450 I get my best fuel mileage (a little over 8MPG) if shifting RMS's stay in the range of 1710-1800 and cruise around 67-68MPH in OD2.

I've heard others say for the 400,ISL they use 64-65, but this is from my memory, you should verify that. Also, most transmissions shift points are set up for power, not economy, this is why I use the "MODE" or Economy Mode on my transmission around town. This will keep your shift points in the lower, more economy range. You have to find put what RPM range is your most efficient for your engine and stay in that range as much as possible.

You may want to stop by a Cummins dealer or give them a call and ask where the most fuel efficient RPM range is for your engine. My guess is - if it's an ISL it will be in the range of 1710-1790.

No I never use the dash calculations, I gather mileage when I fuel and do those calcs myself. I keep a running spreadsheet with the averages. Additives won't do a thing for fuel mileage if you can't find the right RPM's. The time to add additives is when you are getting top MPG, and want that extra 1/10 gallon.
Thanks, I'll try a few different speeds and see if that helps. In California I stuck to the 55 while towing, and mostly 60 everywhere else with a few exceptions. I seldom use the generator, (probably more to keep it lubed up than anything) and often use the economy switch . 60 mph is running at 1800 rpm .
__________________

__________________
2008 KSDP/2013 Flex
2nd year Fulltimers and still loving it.
rlott2k is offline   Reply With Quote
Reply

Tags
cummins, fuel, dutch star



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
2017 Dutch Star 4369 Fuel Mileage LK23 Newmar Owner's Forum 23 11-21-2016 11:07 PM
EPA sticker location on 2006 Newmar Dutch Star 400 cummins Redbaron1949 Newmar Owner's Forum 2 09-11-2016 04:56 PM
2002 Dutch Star 4095 Fuel Mileage Airlifter Newmar Owner's Forum 6 07-21-2016 05:52 PM
Cat C-9 400 or Cummins 400 gnlandrus Class A Motorhome Discussions 7 06-07-2015 01:42 PM
400 Cummins mileage help highcountry Winnebago Industries Owner's Forum 10 03-13-2012 10:24 AM

» Featured Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 10:17 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.