Cat Vs Cummins, need printed specs, where to find

[FIRE UP]

Gents,
We're about to embark on a pursuit to acquire a Diesel Pusher Motor home. I'm in the process of learning about CAT vs Cummins engines. However, finding specs on both manufacturers engines for RVs, is like CIA stuff. For some of you it might be easy. But, being new, I'm trying to find printed information on just what engines, versions of engines, changes to engines, OF EITHER ENGINE MAKER, FOR MOTOR HOME APPLICATION. But, it ain't that easy.

For Cummins, there's the ISC, ISB, ISL, and so on and even finding a list or sheet of what was offered from Cummins, on any year make or manufacturer seems secretive. I know you can look up any "For Sale" ad in CL or the TRADER, and see "330" or 300 or 350 etc all day long but, trying to find exact specs on these motors at least to me, is not that easy.

For instance, there's 340HP Cummins that are less torque than 330HP Cats. So, I hope I haven't made this a complicated question, I'd just like to know if a coach has a 300HP Cummins, a 330HP CAT or anything else, I'd like to be able to refer to a chart that I can save and be able to determine if a particular engine will do for our needs in a given length coach.

Also, what's weird to me is, many coach manufactures will put only a 300HP engine in their coaches all the way up to 37'-38' and then they only go to 330HP versions to 40' or maybe even longer. But, in our quest, we've noticed that Itasca quite often, used a 350 HP in their 34H models. Now that's more to my liking. A lot of power in a smaller motor home. Thanks for your assistance here. Surely appreciated.
Scott

[Tha_Rooster]

You will also find it has a great deal to do with the chassis and the age of the unit. I have a 40ft with a cat. 400 Hp and 1250 torque.

[wkdwitch]

Not a gent, but been there done that made the decision. IMHO you need to narrow the field a bit. Most decide on a length range. I knew 34-37 ft to fit where I wanted to go. Then a year range, not all engines offered all years, nor all manufacturers. So pick one, two or three makers and a range of years. In 2005 I knew 2003 or 2004 would suit my purse. Then I looked at floorplans and other important to us features and decided on the mfgs. Gee....then I looked at the engines offered in that group. My yr and model had a cummins or a cat.....I am frugal and took the 300 ISB and average a consistent 10 mpg on flat trips. I ignore mpg in mountains and just enjoy.

[historyljc]

Scott,
When you're calculating what size and specs of the engine you need be sure and look at the weight rating for that chassis year. Newer coaches have bigger engines that were not needed in earlier years because they are a lot heavier now. Example: Allegro Bus 40': 2002 came with a 330 hp Cummins ISC, GVWR - 29,410 lbs, 2011 comes with a 450 hp Cummins ISL, GVWR 39,000 lbs. As a practical matter CAT and Cummins are both good engines. For a given year, one may be a bit higher on HP the other on torque. Normal driving you probably wouldn't notice the difference. First place to start looking is at the floor plan, furnishings and quality build. They must be suitable to your needs or you're not going to be a happy camper. Most diesels will push coach down the road at a faster speed than the maximum for which the tires are rated.

[FIRE UP]

To all who've replied,
Serious thanks to your thoughts here. Yep, we know and realize that there's multiple check boxes to picking out a coach. Length, floor plan, chassis maker, engine mfg, and a host of other specs. But, we're not locked into any single maker or length just yet. We took a test drive in an '07 34H Meridian with the Cat 350 in it and that spoiled both of us.

I'd driven a diesel coach before but it was quite a while ago and barely remembered the throttle response etc. But, this thing, whew man, was incredibly fast and powerful. And, we really like the floor plan, outside storage, and just about every other aspect. But, just about when we were to start the negotiations, the sales MGR came up to the coach and put a "Sold" sign on it. What a bummer.


Anyway, that was our basis points to start our search. We just recently test drove a very nice '03 34' Kountry Star with the 5.9 300 HP in it. It did well with no load. But, when we hooked the Jeep to it, it made quite a difference. Not Killer but, the rig noticed the load was there alright, and that was on flat ground.

So this is what lead me to the question above, what's the specs, how do I find them, what's main differences, what does all the nomenclature mean etc. etc. etc???? So, in my search for all that, it just got more confusing because I could not find anything that was sure thing that stated: This is a listing of all the Cat motors used on all the RVs since .... date. This is a listing of all the Cummins motors used on/in all the RVs since ..... date. This is the specs on all those motors, HP, torque, etc.

I'm getting there, but, it's a bit of info here, some there but no big spread sheet that lists them all. I guess that was/is expecting too much. My thought here is, once I learn all the designations of the engines, and rehearse what was used in various years and or what improvements were made at what time, I'd have a better idea of the power/torque of any given engine in a coach we are thinking about.

Yes, I know both are good engines, and some of you say the both will get you down the road, True. But, the earth isn't flat so, I'm tired of pulling grades at a slow, crawling pace with a gas unit and in this change, I'd like more power. Now before anyone goes bazookoid here, I don't need to be the first at the top of all grades. I don't have to climb Tioga pass or the Grapevine or 15 into Vegas as 85 mph. I just want plenty of reserve power when I want it. I normally cruise at around 60 plus or minus. But, I approach a hill, I want to relax more, knowing I've got plenty of power and don't have to scream the thing just to do 35-40 up an average grade.

Again, thanks for your response here. Much appreciated.
Scott

[Caemlyn]

Well, I drive a 38' 99 Holiday Rambler Endeavor with a Cummins 275 ISB and tow an 07 Ford Edge... oh and I run at just about 95% of GVWR of 24,850 and I climb the Grapevine at 50-55 MPH.... so more than enough to get the job done. Oh and I average 9.75 MPH from Sacramento to San Diego and get 12-13 running up and down the central valley all year long. Reasonable balance of power and mileage. Just my experience.

[bob109]

Here's some great info on On Highway Cat Diesels!

Cat Products: Applications>On-Highway Truck>Support>Engines

[FIRE UP]

Ladies and gents,
Again, thanks so much for your input here. I'm learning day by day. You know, when I was growing up, and just got my drivers licence right at the peak of the factory hot rod production, which was in and around 1965-1970, it was very common for the factories to put rather large motors, high performance motors in relatively small cars. Cars like Chevelles, Novas, Mustangs, GTOs, 442s, and many in between. But it seems in motor homes, you have to go to a monster 40' rig or larger to get a "stronger, larger, higher performance" engine, in either CAT or CUMMINS.

I certainly don't want to sound like I need a hot rod motor home. That's not my intention. I'm just one of those that liked the 427 cu.in. 425 HP engine in a chevelle. It doesn't mean you've got to use it 24/7 but, it's got the reserve power if and when you need it. Well, that's the correlation I'm trying to convey. One of the rigs' we're looking at has this kind of HP/Torque to weight/length ratio. It's the 34H Itasca Meridian with the CAT 350.

We test drove one in Quartzite last January and nothing slowed this rig down. There's not much by way of grades in and around Quartzite for a good test but, of the slight grade/hill we did run on, it was like it was down hill when I was going up it. Again, I don't need it to go 105 on the straight runs, I just want to be able to hit a grade, and pull that grade at 50-55-60, what ever I want to run at, I can do it, even towing my jeep.

Well, we'll look around, pick out a nice rig that we can afford and have a great RV life. Thanks again for your help here in this issue. Appreciated.
Scott

[94-Newmar]

I honestly think the HP numbers listed by these manufacturers is like tossing dice in the air. My 94 8.3C is only rated at 300hp in our 40' Kountry Star but even with a decent load in a trailer I've not been able to slow it down going uphill - AND I'm getting right at 10mpg at 62mph. A friend of ours has an 05 Discovery 39' 330HP CAT and when we caravan together I'm easily able to outpull him on any grade.

Last fall I got to drive a friends 04 or 05 37' Monaco with the 5.9 ISB (rated at 300hp I think) out to NJ from Ohio. Even on some monster hills that thing pulled very strong and never seemed as if it was laboring at all, almost 10mpg at 60-65mph the entire way out there.

[FIRE UP]

94 Newmar,
Thanks so much for your appreciation of ideas. Again, I'm kind of new to the diesel motor home scenario so, I'm just really trying to envision a happy ending by making a educated selection on our future purchase. I'd hate to put down a hansom sum of coin only to find out I did not do my homework and should have known better. Well, that's why I'm here, to learn what's what in the world of RV diesel.

In my latest subsection of specs for diesels, saw a rig for sale that had a Cat 300 HP in it that was supposed to be the same exact torque as the 330, 860 ft lbs. Now, as I recall, the 330 is the same torque as the 350. Hmmmm.
Scott

[bob109]

Quote:

Originally Posted by FIRE UP 94 Newmar, Thanks so much for your appreciation of ideas. Again, I'm kind of new to the diesel motor home scenario so, I'm just really trying to envision a happy ending by making a educated selection on our future purchase. I'd hate to put down a hansom sum of coin only to find out I did not do my homework and should have known better. Well, that's why I'm here, to learn what's what in the world of RV diesel. In my latest subsection of specs for diesels, saw a rig for sale that had a Cat 300 HP in it that was supposed to be the same exact torque as the 330, 860 ft lbs. Now, as I recall, the 330 is the same torque as the 350. Hmmmm. Scott

I, like you, spent uncounted hours researching for that "perfect MH. On the top of my list was a machine with sufficient power/torque that would walk, not crawl over mountains and cruise down the highway and achieve some decent MPG doing so. I finally settled on a unit with a GVW of 26,000 lb and 5k towing capacity. My MH has the 330hp Cat with 860 ft lb torque. On my past two trips from Pa. to Fl. I averaged 9.87 mpg, with a high of 10.10 mpg. The earlier version of the 2001.5 Discovery was equipped with a 300 hp Cummins with 660 ft lb torque and was considered "under powered" by those owners, hence Fleetwood gave the Discovery a boost by installing the CAT 330/860.
Here's the original press release info!
Fleetwood RV Introduces 2001.5 Discovery and Pace Arrow Vision At RVIA. - Free Online Library
My particular motor is a 3126E Cat which is the earlier version of the updated C7. Changes to the head, cams and injectors were suppose to improve the motor. From all accounts I've read, the only "improvement" achieved with the new configuration was "reduced fuel mileage". The C7 usually get 7 to 8 mpg on their best days and like the 3126E, it's rated at 330/860.
Coach weight, rear end gearing, tire size and of course hp/torque all fingure into the total performance of every MH. Doing your homework in advance will resulf in your selection of the "right unit" for you.
Best of luck on your final selection

[bob109]

Here's some additional info from Cummins on their diesels.

Cummins Engines

Like the Cat Diesel info I gave earlier, Cummins uses a ECM to regulate HP/Torque Curves on their motors. The ISB has several power ratings all achieved with the same cubic inch block. The same applies to their ISC, ISL, ISM and ISX engines. Researching the CAT Engine info reveals the same methodology. That said, if you find a coach you like, check the chassis and motor serial numbers and visit a local dealer. With that info dealers can give you the specefics of your particular MH to include the axle ratio, HP/Torque rating, fluids capacaties etc.

[PASODAVE]

Fire Up.
You and I are from the same generation (roughly) and recall the muscle cars of the 60's and 70's. Remember you are hauling a lot of weight that is not very aerodynamic, so the old adage from the muscle car era applies; cubic inches DO matter. 300 HP from 6.7 liters or 300 HP from 8.8/8.9, which do you think is going to haul the load better and faster? (But like the old 427, fuel milage does go down)

[FIRE UP]

Well guys,
I can't thank you all enough. It definitely is a learning experience. And, if you've been in the arena for a while, you know the ropes, angles, short cuts, good points, bad points and where to go for info. I'm getting there. So, although I've been inside, outside, under, on top of, worked on, outfitted, and drove fire trucks for over 35 years, and, was around diesel engines my whole life, THIS is a different application altogether. Although I was impressed by the test drive I did with an '03 Kountry Star with the Cummins 300 and a Banks controller, I can't bring to bare, the weight that I'll be dragging all over the U.S in a 300 hp unit. So, we're on the hunt for a nice 330 Cat powered unit. Thanks again for all your help and encouragement. Much appreciated.
Scott.