Used 350 HP vs 400 HP DP

[2 Stroker]

Originally Posted by MTK46

Found a 04 Tiffin double slide ISL 400 hp, 05 American Coach C9 Cat 400 HP double slide both are in the 77,000 mile range. 04 asking $74,900, 05 $79,900. Also a 03 Monaco Windsor ISL 370 HP triple slide 1 1/2 bath also asking $79,900. All three of these are at the same dealership. After having triple slide 5th wheels I'm not sure about going back to a double slide RV.

Here is a good looking 3 slide in your price range plus it has a tag.
https://www.rvonline.com/single-ad.a...SearchMethod=1
2 stroker

[Old Scout]

IMHO, HP rules--the more the better, you won't regret getting a few more HPs and a few more Ft/Pds. But the real advantage to an ISL over an ISC is the "Jake" brake--no muss/no fuss, its make driving a breeze. HP to weight is the key--ISL in a 40ft with an Allison MH3000 tranny is a great set-up. Bigger coaches, more HPs I guess--but can't really see the need for a tag or the 500-600 HPs that comes with it. 8-9 MPG with a ISL on average is about "average". Safe travels.....

[blacktruck]

Originally Posted by MTK46

I'm looking to move from 5th wheel to DP. My price range is in the $60-80k range. Most DP in that price range are 02-05's which I'm fine with. Most not all that I've found are 350 HP and that's where my problem occurs.
I've been RVing for 30+ years and going up grades at 40 mph just isn't for me. My F-350 is rated at 400 HP with 800 ft. of torque. I'm at 23,5k total weight. My concern is will I be happy with a 350 HP DP out here in the desert SW where we have REAL grades & Heat.
So I'm looking for feed back from folks with 350-400 hp DP that have pulled grades out here when it's 110+. Have gone over Wolf Creek Pass or any others in the Rockies.
Oh also looking at side radiator DP only.

Seems to me you have already made up your mind that 350 HP won't be enough in a DP. I won't try to change that. There have been a few good comments already on that. My question is about your statement regarding side radiators. My current DP (350HP ISB) has a rear mounted radiator. Is there something that I should be watching with that? Mine has been faultless over the few years I've had it. Just curious what your objection would be to one of those.

[jleamo1]

I agree on the Windsor also. The 370HP ISL can be taken to a Cummins dealer and bumped to 400, and you know its done right. Torque, don't loose sight of that important part.
Depending on wind and my speed, I have broken the 10MPG already and have also been in the upper 7's. ISL 400 with 1200 lbft of torque.
On a few occasions I have pulled some large hills on the PA turnpike at 60 MPH out in the western part of the state, if you see the hill and get into the throttle and with a manual downshift it will hold your speed up over the hill and continue to accelerate, once you are on the hill and trying to pass someone it will do it but not like a pickup truck unless you preplan once you know the coach.
A motorhome I believe is less aerodynamic than a pickup with a trailer.

[jleamo1]

Originally Posted by blacktruck

Seems to me you have already made up your mind that 350 HP won't be enough in a DP. I won't try to change that. There have been a few good comments already on that. My question is about your statement regarding side radiators. My current DP (350HP ISB) has a rear mounted radiator. Is there something that I should be watching with that? Mine has been faultless over the few years I've had it. Just curious what your objection would be to one of those.

Two things come to mind, engine access for repairs can be tough with a rear radiator and the rear radiators tend to get gum up with dirt faster than a side one.
I will say I have worked on some DP's with a side radiator that were miserable to access anything, the last one was a Tiffin Allegro Bus, 2005. My hands looked like they went into a meat grinder .

Make sure you look at engine access also, that will cost you more $$ if you cant get to it and have to pay someone else to attempt it.

[Mr_D]

Originally Posted by gemert

MPG avg. went down from 7.2 to 7.1 while out west last summer. That is reading from the computer. Actual milage is probably about 6 because of generator and Hydro Hot use.

I don't understand statements like this!
The mileage doesn't go up when you use the generator and Hydro Hot, it stays the same but your fuel usage does go up. You are still getting 7.1 or 7.2 when the generator and AquaHot are in use but you are using more diesel but the mileage is the same.

[gemert]

Originally Posted by Mr_D

I don't understand statements like this!
The mileage doesn't go up when you use the generator and Hydro Hot, it stays the same but your fuel usage does go up. You are still getting 7.1 or 7.2 when the generator and AquaHot are in use but you are using more diesel but the mileage is the same.

The computer "reads" the mileage based on engine fuel usage in a way that I can only guess at and says I get an average of 7.2 mpg while I was in the East, mostly Florida. While out West all summer, driving in a lot of mountains my computer says I got 7.1 mpg. Easy I think, more mountains, less mpg! The generator and HydroHot use diesel and when I figure my mileage myself, between fill ups, using my 48 year old high school math skills, I come up with 5.9-6.0 mpg. We drive with the generator on a lot in the summer to keep the coach cool and of course, HydroHot heats our water for showers. So in summary, the approx. 6 figure is a combined figure that equates to actual mileage including the diesel used for HydroHot and generator use. Not sure if other people do this type of calculation or not. I don't usually care but I was curious and had nothing better to do at the time. So in effect I guess the mileage is the same, this was just a way for me to make it easier for my simple mind. I hope I have cleared up your questions MR D!

[MTK46]

Originally Posted by 2 Stroker

Here is a good looking 3 slide in your price range plus it has a tag.
https://www.rvonline.com/single-ad.a...SearchMethod=1
2 stroker

I had found the same thing but much closer to me.

https://www.rvtrader.com/dealers/Aut...ness-120166582

Also found a triple slide 04 Newmar Mountain Aire with 66k miles ISL 400 HP for $74,000 OBO

[Gary RVRoamer]

Look at the weight to horsepower ratio. The rule of thumb for RV builders is that 100 lbs per hp is adequate, but the level of hill climbing performance that delivers is probably gonna leave you unhappy. Your truck was under 60 lbs/hp, so go figure!

My most recent coach was a 370 hp ISL and we traveled at about 37,800 lbs, so right near the 100 lbs/hp target. It was 35-42 mph on long steep grades, even though it never raised a sweat climbing them. The engine and tranny settled down at the peak hp sweet spot and that was the best she was gonna do. I learned patience, but always hankered for a little more hp, even just 450 or so. The most upgrade I could get (from Cummins) for my particular ISL was to 400, and I didn't think that was enough to make much difference.

[slickest1]

If it were me I would also go to the ISL 400. The 370 will only have an exhaust brake where the ISL will have the full engine brake.
The ISL will have 200+ lbs of torque more than a 350.
Most Cummins ISC and ISL engines built before 2003 have the Caps Fuel system on them which can be more problematic than the common rail on the 04 and up. There were some engines 04 and up that have a wrist pin recall but there is a list of serial # you can check for that.
I have an ISC 350 in my 33000 lb. coach and it is alright but slows down on the hills. If I were to buy another coach I would get one with the ISL for all the reasons above. But I have gotten used to mine the way it is and am quite content with my 8mpg av.

Another option would be an earlier coach with the ISM 500, there are many around with not to high of mileage.

[DD788Snipe]

Mike I purchased my coach 3 years ago. It came with the 350 ISL. This engine is rated at 1050 ft/lbs of torque. With the Saturn in tow my GCVW was 33,000 lbs. It pulled the passes in the west very well as long as I anticipated the grade and down shifted manually. I averaged 7 to 8 MPG at 62 mph and it came with a Jacobs exhaust brake which works well in conjuction with the Allison trans. I paid the bucks and had the ECM reflashed to increase the the HP to 400 and the torque to 1200 ft/lbs. We gave the Saturn to the grandaughter and bought the Colorado which increased the GCVW to 35,000. That changed the whole complexion of the power band. I now run 65 to 70 mph and still get 7 to 8 mpg and on passes I never take it off the cruise control. My speed never drops below 60 even on 6 to 7% grades and the tranny rarely down shifts out of 6th and if it does its only to 5th. Also I have a side radiator and the engine never runs over 200*. As far as the exhaust brake it does a great job and yes a compression brake is better but don't let that be a deal breaker. The ISL is a great engine. Powerful and dependable. I wasn't unhappy with the 350 but WTH like everyone else I wanted more power. BTW the 370 ISL is rated at 1200 ft/lbs of torque FYI. Torque is what makes the power in a diesel engine. If this coach would have had the 370 in it I would have left it alone. Here's a link that I started about my coach: http://www.irv2.com/forums/f123/cumm...se-272964.html
Happy hunting.

[jleamo1]

Originally Posted by MTK46

I had found the same thing but much closer to me.

https://www.rvtrader.com/dealers/Aut...ness-120166582

Also found a triple slide 04 Newmar Mountain Aire with 66k miles ISL 400 HP for $74,000 OBO

Mike, that Monaco is nice! The CAPS fuel system mentioned has some problems that can be modified to correct. there is another post on that under the Cummins section.

[barmcd]

Originally Posted by blacktruck

Seems to me you have already made up your mind that 350 HP won't be enough in a DP. I won't try to change that. There have been a few good comments already on that. My question is about your statement regarding side radiators. My current DP (350HP ISB) has a rear mounted radiator. Is there something that I should be watching with that? Mine has been faultless over the few years I've had it. Just curious what your objection would be to one of those.

I'm a DIY type and it didn't take me looking at very many motor homes to decided I didn't want a rear radiator unit due mainly to engine accessibility.

[Frutza]

We have an 05 with a C7 @ 350 hp, added a Mp8 programmer and she pulls grades quite well, haven't been west since installed, pulled well thru Pa and the Adirondacks, don't really remember my speed but was passing trucks and other Rvs on grades. 34k with trailer.
Happy hunting