I was wondering if anybody had an experience with a ISB-XT turbo diesel 6.7 liter, 360 hp @ 2600 rpm, 800 ft. lbs torque @ 1800 rpmMy main concern is will it be enough pulling a 5600# Avalanche thru hill and mountains??

It depends entirely on how big and heavy the coach is.

The coach is 40'7" OALGVWR=31,000#GCWR=41,000#

meubank wrote:The coach is 40'7" OALGVWR=31,000#GCWR=41,000#Those numbers say it can tow at least 10,000# if the hitch is rated high enough to do it.

I am 42,350 and 32,350 37 ft, pulling 4400 lbs, no problems but I do down shift on really big mountains and hills.I have 21,000 miles on the MH and have passed over the rockies twoSo the answer is yes

are you able to maintain speed limit on the flat?

360 Hp Cummins | Good Sam Community

zb39
Explorer
Jun 24, 2014
et2 wrote:
zb39 wrote:
Based on over 100k miles driving 4 coaches, Go with bigger every time. My first DP was an ISC 8.3L because I knew the ISB at any HP rating did not have enough torque. I now have a ISM 10.8L Love it.
Although I wouldn't mind getting the big ISX 15L. The smaller engines will probably do the job, but the west is vast and tall and you have to worry the whole way. Good Luck.

So Cummins, Frieghtliner, Fleetwood must be repairing those little ISB's left & right as they've been put into many different MH platforms for some time. I doubt it's been a issue for anyone who has one, anymore than a larger ISC or any engine. Design limits and caution just thrown into the wind by the engineers ??

All those gassers & little ISB's must be terrified heading to the vast and tall great out West. In reality since you've really never driven a ISB, you don't have any experience with it.
I guess I should have added the words. For me. Someone in there. I never said they wouldn't do the job and I certainly never said they break in any way. They just aren't enough for me. After crossing the Rockies more times than I can remember. I want a lot of power. I don't like maxing anything out. I feel things last longer if I don't run them at full power all the time. I have driven 3 coaches with isb. Dads, brothers, and brother in laws. All 3 of them agreed with me and all traded coaches after a few years. Buy what you want and enjoy your day
ISB didn't have enough torque for what? I would suspect that is your personal opinion, as they go up and down and straight and flat just like any other MH. Unless of course you have some data to support your statement.
kedanie
Explorer II
Jun 22, 2014
Our little ISB 6.7 340HP pulls the mountains here in the great southwest with a 2012 Grand Cherokee attached. I17 going up to Flagstaff passing the slower trucks with ease. No problems what so ever all while getting 9-10 mpg with the toad on the back.

Keith
et2
Explorer
Jun 22, 2014
zb39 wrote:
Based on over 100k miles driving 4 coaches, Go with bigger every time. My first DP was an ISC 8.3L because I knew the ISB at any HP rating did not have enough torque. I now have a ISM 10.8L Love it.
Although I wouldn't mind getting the big ISX 15L. The smaller engines will probably do the job, but the west is vast and tall and you have to worry the whole way. Good Luck.

So Cummins, Frieghtliner, Fleetwood must be repairing those little ISB's left & right as they've been put into many different MH platforms for some time. I doubt it's been a issue for anyone who has one, anymore than a larger ISC or any engine. Design limits and caution just thrown into the wind by the engineers ??

All those gassers & little ISB's must be terrified heading to the vast and tall great out West. In reality since you've really never driven a ISB, you don't have any experience with it.

ISB didn't have enough torque for what? I would suspect that is your personal opinion, as they go up and down and straight and flat just like any other MH. Unless of course you have some data to support your statement.
Deano56
Explorer
Jun 22, 2014
Avalanche weighs 5600 pounds?
zb39
Explorer
Jun 22, 2014
Based on over 100k miles driving 4 coaches, Go with bigger every time. My first DP was an ISC 8.3L because I knew the ISB at any HP rating did not have enough torque. I now have a ISM 10.8L Love it.
Although I wouldn't mind getting the big ISX 15L. The smaller engines will probably do the job, but the west is vast and tall and you have to worry the whole way. Good Luck.
et2
Explorer
Jun 21, 2014
DanTheRVMan wrote:
http://prevostcommunity.com/PDF/Motor%20Home%20Fuel%20economy.pdf

Figure 4 will show you speed up hill which is solely a function of weight/hp. But everyone should read the whole thing imo

this is why people see little difference in speed up hill between 360 and 380 hp engines as they are very close and the higher hp mh usually weighs more so weight/hp is very comparable.

You should not have any problems

Excellent link. Explains a lot! Good read.
et2
Explorer
Jun 21, 2014
JimM68 wrote:
ET2, your pickup truck, towin any currently manufactured fiver, did not weigh 43,000 pounds! Not even close.

It gets confusing these days with the pickup truck motor's HP rating overlapping the cummins ISC 8.3 liter...

The 8.3 has one thousand fifty foot pounds of torque. This is computer limited due to the rating of the Allison MD3000 transmission (the engine can actually put out much more)
These engines were rated anywhere from 300 to 380 HP, depending on application, always with that same 1050 torque rating.

Ours, a 360, struggles some up the big passes in the west, down to second gear and 40mph sometimes.
After having driven a v10 gasser over these same "hills" at 20 mph, 5500 rpm, in first, I just thank my lucky stars for that big ISC.

While Fleetwood must know what they are doing putting the ISB in the 34 and 36' versions of this motorhome, I personally would get the forty footer just to get the bigger engine.

Jim, I understand the weight difference. However, the fiver and dually with a 90 gallon aux fuel tank weighed every bit of 24,000 lbs combined. My motorhome loaded is almost 28,000 lbs and the toad is now 3900. So combined its 31,000. A 7000 lb difference - not 17,000 lbs as you've suggested.

The max GVWR for the MH is 32,400 and a " combined" or GCWR of 42,400lbs. I,m well under the allowable weight specs. So based on what the OP asked - I'm running within the designed platform of my rig with the same engine inquired about.

Based on past experience with the same engine designed for a lower hspwr and torque with somewhat similar towing I had zero problems towing the big hills out west. This engine has been upgraded to 360 hspwr and more torque than the pickup combination I had at the time. There are some other differences as well. One being the Allison 3000 transmission. Far superior to what was put in my 2010 pickup. If I'm not mistaken there is a lot more cooling capability in the motorhome vs the engine in the pickups. So there are some benefits and upgrades to the engine and drivetrain in the motorhomes.

I'm not saying it's the greatest mountain pulling beast - but I feel 100% comfortable I'm capable of pushing this MH and toad over any hill out west. Given, it'll be 30 - 35 mph, but so what.

So the real answer is YES it will do what the OP asked - even in a 42' MH. I didn't buy mine with mountain driving in consideration. I knew if I stayed within what the manufacture specs are one way or another I could do it. We considered the Discovery which had the ISC and bigger engine. But what we would have got for the extra $70,000 wasn't worth it to us. So we saved a boat load of cash.

To the OP - yes it'll do it loaded properly - take your time - enjoy.
DanTheRVMan
Explorer
Jun 21, 2014
http://prevostcommunity.com/PDF/Motor%20Home%20Fuel%20economy.pdf

Figure 4 will show you speed up hill which is solely a function of weight/hp. But everyone should read the whole thing imo

this is why people see little difference in speed up hill between 360 and 380 hp engines as they are very close and the higher hp mh usually weighs more so weight/hp is very comparable.

You should not have any problems
JimM68
Explorer
Jun 21, 2014
ET2, your pickup truck, towin any currently manufactured fiver, did not weigh 43,000 pounds! Not even close.

It gets confusing these days with the pickup truck motor's HP rating overlapping the cummins ISC 8.3 liter...

The 8.3 has one thousand fifty foot pounds of torque. This is computer limited due to the rating of the Allison MD3000 transmission (the engine can actually put out much more)
These engines were rated anywhere from 300 to 380 HP, depending on application, always with that same 1050 torque rating.

Ours, a 360, struggles some up the big passes in the west, down to second gear and 40mph sometimes.
After having driven a v10 gasser over these same "hills" at 20 mph, 5500 rpm, in first, I just thank my lucky stars for that big ISC.

While Fleetwood must know what they are doing putting the ISB in the 34 and 36' versions of this motorhome, I personally would get the forty footer just to get the bigger engine.
et2
Explorer
Jun 21, 2014
dieselmaniac wrote:
et2 wrote:
eheading wrote:
What brand of RV are you looking at? It is extremely rare for a 40' motorhome of any price range to have the IXB-6.7 engine in it. A lot of them have the 360hp ISC engine in them that has 950 ft-lb of torque. Unless you are bothered by the slower hill climbing ability of this combination, in my opinion it would be more than adequate to meet your needs.

Ed Headington

I'm not so sure you're accurate. I think you meant ISB 6.7. Many motorhomes are (were) equipped with the ISB 6.7. 0ur 2013 Fleetwood Expedition has it in it - 360 hspwr & 800 lb-ft torque. It's almost 42' long. I believe the Discovery (2013) got the ISC 6.9 - 380 hspwr - 1200 lb-ft torque.

We've had no issues pulling a 4600 lb Jeep Liberty. It's rated to pull 10,000 lbs, I believe it will.

something rated for 10K does not always correlate to what motor the unit has. I have a 425ISC in my 40ft unit with a 50HP module add on
I pull a 3600lb toad and I barely have adaquite power on mountain passes.I would not ever want to own the same size unit such as your unit with a ISB 360HP.

But if the manufacture say's you're within the weight specifications on the coach and combined weight specs and it has room left over - the rig can pull a 10,000 lb toad, trailer, dolly. My setup as traveling would allow me a 10,000 vehicle being towed and still under the weight capacity.

I have no doubt it would be fine. Not going to win any races up the mountain side, but it'll get me up and down just the same with probably more fuel in the tank at the end of the day.

Just curious why you wouldn't go up a hill in a MH designed to do it. What is the problem with your coach on the mountains? I pulled a 17,000 lb fiver and the dually weight up and down the mountains and switchbacks traveling to Yellowstone with a ISB 6.7 engine with less horsepower and torque than what I currently have.I would do it with this MH without concern anymore then anyone else.