Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

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 12-17-2014, 05:18 PM   #15
Senior Member
 
Join Date: Feb 2013
Location: Graham, WA
Posts: 772
I'd be more concerned about torque than hp. Hp is calculated off the torque and rpm. More rpm, more hp. In our applications we're typically working at relatively low rpm even though the engine may be rated for higher rpm. Our mh gvw is 32K lbs. Our Cat is rated at 860 lb ft and I'd love a couple hundred more.

"Horsepower sells engines and cars. But torque moves the car." - Kevin McClelland, Flowmaster Mufflers
__________________
2006 Gulfstream Friendship G7, Cat C7 and Allison 6 spd
Honda VTX and Cruiser Lift on the back
Blue Ox Aladdin, Brake Buddy, 2019 Chevy Blazer RS toad
Dennis4809 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 12-17-2014, 05:41 PM   #16
Senior Member
 
Papa_Jim's Avatar
 
Outdoors RV Owners Club
Join Date: Oct 2009
Location: Manitoba,Canada
Posts: 2,789
Quote:
Originally Posted by Dennis4809 View Post
I'd be more concerned about torque than hp. Hp is calculated off the torque and rpm. More rpm, more hp. In our applications we're typically working at relatively low rpm even though the engine may be rated for higher rpm. Our mh gvw is 32K lbs. Our Cat is rated at 860 lb ft and I'd love a couple hundred more.

"Horsepower sells engines and cars. But torque moves the car." - Kevin McClelland, Flowmaster Mufflers
As an old diesel man, I've always thought the same way. If I looked at 2 similar coaches with similar horsepower, one with an ISB @ 650lb torque, the other with an ISC @ 850lb torque, I'd figure that on a long hard grade, the ISC would do a lot better job.

Jim
__________________
2016 Creekside 23RKS
2012 Ram 2500 Laramie 4X4 Cummins 6.7L
Canada, eh?
Papa_Jim is offline   Reply With Quote
Old 12-17-2014, 05:49 PM   #17
Senior Member
 
PushedAround's Avatar
 
Tiffin Owners Club
Join Date: Sep 2012
Location: Ambler, PA
Posts: 2,853
Blog Entries: 7
Quote:
Originally Posted by 46490 View Post
I was told that the ISB 6.7 340 has 660 torque? Was I mislead?
It may depend on the year. My 2010 ISB is 340 & 660.
__________________
Larry & Cheryl Oscar, Louie, Ranger & Henry (our Springers)
PushedAround is offline   Reply With Quote
Old 12-17-2014, 07:31 PM   #18
Senior Member
 
Join Date: Feb 2013
Location: Graham, WA
Posts: 772
Cummins website shows the ISB peak torque varying from 520-800 lb ft. ISC is rated at 1050. These are based on a 2013 engine. Then there's the issue of a 2500 Allison with the ISB and the 3000 Allison with the ISC.
__________________
2006 Gulfstream Friendship G7, Cat C7 and Allison 6 spd
Honda VTX and Cruiser Lift on the back
Blue Ox Aladdin, Brake Buddy, 2019 Chevy Blazer RS toad
Dennis4809 is offline   Reply With Quote
Old 12-18-2014, 06:33 AM   #19
Moderator Emeritus
 
Gary RVRoamer's Avatar


 
Join Date: Jan 2000
Location: West Palm Beach, FL. USA
Posts: 27,563
As Steve says,the torque spec is the peak torque, so the ECM could limit what the transmission actually sees by limiting the RPMs so that they never reach peak. Allison says the 2500 MH can handle up to 700 lb-ft of torque with "SEM or torque-limiting", which is probably what Steve was referring to.

The ISB is actually capable of up to 385 hp and 865 lb-ft of torque, but the engine configuration used in motorhome applications is a max of 350 hp & 660 lb-ft (2015 spec).
6.7L Cummins Specs


Freightliner says it is delivering the XCS chassis with a 6.7L ISB at 340 hp and 700 lb-ft of torque, coupled to a Allison 2500 MH.
__________________
Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL
Gary RVRoamer is offline   Reply With Quote
Old 12-18-2014, 06:56 AM   #20
Senior Member
 
DegoRed's Avatar
 
Fleetwood Owners Club
Join Date: Jun 2012
Location: Austin, TX
Posts: 879
Had an occasion to do a confrence call with both Spartan & Cummins on the line together to answer some questions regarding my engine brake. They both had to have my engine serial number and ECM serial number. Together they were able to confirm my exact set up and programing. While I had them both on the phone, also asked a bunch of questions regarding various items.

One of the items we discussed was the HP & TQ. Both Cummins & Spartan had the exact same response. Cummins delivers the exact same motor to all, each builder then in turn chooses what ECM and programing to apply. This is how you can have the same ISB in my case engine, with several different programing options all from the same builder.

My particual set up is 350HP & 750TQ, however I have a Allison 3000 transmission. For my 42ft rig, 95% of the time it is fine, no real complaints, but have been on some grade that left me wanting a lot more (Reno to Cali & Phoenix to Kingman) are two that recently come to mind.
DegoRed is offline   Reply With Quote
Old 12-18-2014, 07:01 AM   #21
Senior Member
 
Entegra Owners Club
Spartan Chassis
RV Trip Wizard
Join Date: Nov 2014
Location: clearfield, utah
Posts: 630
I just got off the phone with cummins - gave them my engine serial number and was told that the 340 hp is the max power for my motor. Cummins does offer a retro fit kit but each kit is custom made for the specific motor and they said it was expensive buy covered under warranty.
__________________
2020 Cornerstone 45W, 2016 Ford Focus, Charlie the Golden Retriever the owner but not the operator
46490 is offline   Reply With Quote
Old 12-19-2014, 09:06 AM   #22
Junior Member
 
Join Date: May 2014
Posts: 4
It's in the torque

I'm intrigued by all the replies that overlook the lack of peak torque in the ISB relative to the ISC. HP means nothing if the torque isn't there when you it.

I did find instances where the ISC appears to be in coaches after 2010, although the Cummins catalog lists it as a 2010 engine. It is mostly missing after 2010 in brochures.

Also, my 2007 Ambassador, which at the time was the entry level diesel (I don't count the Vacationer) had an ISC with a GCWR of 43000 with 10000 towing capacity (33000 coach and cargo), the new Ambassador with the ISB has a GVWR of only 28000 and 5000 towing (23000 coach and cargo). So the difference in cargo carrying capacity (the big advantage in diesels) is not there.

I have lots of other issues with the new HR vehicles, which I didn't think Navistar could be outdone in, but that's another forum.
kenny449 is offline   Reply With Quote
Reply

Tags
cummins



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
Cummins ISB 350 hp overheat Dmintzer Cummins Engines 41 12-16-2014 10:31 AM
Cummins ISB ISC ISL ISM ISX? Beeper Cummins Engines 10 07-23-2014 06:53 AM
Cummins ISC Multiple Problems BandBRetired Cummins Engines 13 06-29-2014 01:18 PM
2000 Cummins ISC 350 Low Boost. crawbob Cummins Engines 61 12-26-2013 06:42 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 06:41 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.