Comparing older (04-06ish) CAT to Cummins engines

[Jack Klompus]

I found some older threads, but am wondering if there is any current wisdom comparing the 04-07 ish CAT diesels to the Cummins (ISL probably).

I am researching coaches of this vintage, and I am concerned about whether they would be sufficient to pull the coach plus a heavier toad out west. I am learning that some of the manufacturers I am looking at used a Cat powerplant, and most others used Cummins.

In the 40-41 foot range, I am assuming we really need 400/1200 to do this. Is there a strength and weakness between a CAT motor vs an IS_?

For context, I understand much of this is around setting expectations. But I am used to (right now) being able to accelerate up grade while pulling my fifth wheel. I can accept the idea of not doing that, but I am not sure I can accept 35 MPH climbs for example. At some point it becomes a safety issue.

Sorry for meandering there ... thoughts?

[Jack Klompus]

I should add that most of my question centers on longevity and servicing - does this represent a large negative for Cat drivetrains compared to Cummins.

[twojayhawks]

If I remember correct back in the day when Cat was offered, the Cat offering would have been a equal sparring partner size/power wise to Cummins. So the power should not be an issue. I've had Cat & served me well. No complaints.

[Jim_HiTek]

Rule of thumb is 100 lbs/1 HP. So if you have a 36,000 lb vehicle plus toad, you'd want at LEAST a 360 HP engine. Personally, my feeling is 85 lbs/HP is way better. I've had both a 190 HP Cummins, that would barely get 25 MPH up a moderate grade, to my current 330 HP Cat which can go 55 up most grades but I prefer not to.

Reason is that my 190 HP Cummins averaged 10 MPG. Whereas the 330 HP Cat averages 7.8 MPG. Quite a bit of difference just to go up a hill faster by getting a large engine. I am retired and do NOT care how fast I go up a hill. What difference would it make anyway? I've always arrived at a reasonable time. I never go above 65 MPH as it is, and during the last big price increase for Diesel, I've dropped that to 55 MPH.

As far as the engines reliability, that's a lot like comparing Fords to Chevs but I think the Cat is more reliable.

[Jack Klompus]

Originally Posted by twojayhawks

If I remember correct back in the day when Cat was offered, the Cat offering would have been a equal sparring partner size/power wise to Cummins. So the power should not be an issue. I've had Cat & served me well. No complaints.

Thanks! What about current servicing?

[moisheh]

Many Cat shops will not work on Motorhomes. Cummins usually does but they are beyond expensive. If you like a particular MH mfr. they never gave buyers a choice. For instance a Journey in the years you mentioned would be Cat. You did mention whether you were looking for an entry level or high end model. A Bounder might have a C7 or an ISB
Neither meet your requirements. But a Beaver or a Monaco Signature might have a 500 HP engine. Your budget will determine what you buy.

[vito.a]

Caterpillar builds great engines. In 2008 they elected not to meet the newest EPA emissions requirements since most of their business is off road equipment. They still build engines, just not for highway use.
If you are concerned about power you probably need a C9, or larger.
The little Cat 3126, and its successor the C7, are great engines but probably not what you are looking for.
You probably also want to avoid the small Cummins ISB.

[Ray,IN]

Before we bought this MH I asked the same question of my SIL, who is maintenance manager for a nationwide trucking co.
He told me the only difference is CAt engines are more expensive to repair. Dependability and longevity are virtually equal, with CAT being slightly more reliable.

[john1981]

ive driven a bunch of big trucks with cummins and cat power. back when there was a choice, cat was the way to go. the cats always felt like more of a powerhouse than a comparably rated cummins. we had a c13 with over 30k hrs and it ran awesome right up until it lifted the head from overboost. the advantage of cummins is theyre easier to get serviced and cheaper to maintain. all things being equal, id take a cat over a cummins every day of the week, the big ones are awesome.

[Gary RVRoamer]

I think that as long as the engine models comparisons are apples-to-apples, there isn't much difference. For obvious competitive reasons, a C9 Cat is very similar to an ISL, a C7 is close to an ISC, and so forth. I'm sure there are those who would debate in favor of their beloved brand, but at the end of the day a Cat horsepower does the same work as a Cummins horsepower.

[john1981]

Originally Posted by Gary RVRoamer

I think that as long as the engine models comparisons are apples-to-apples, there isn't much difference. For obvious competitive reasons, a C9 Cat is very similar to an ISL, a C7 is close to an ISC, and so forth. I'm sure there are those who would debate in favor of their beloved brand, but at the end of the day a Cat horsepower does the same work as a Cummins horsepower.

the power delivery from cat to cummins is different. a cummins has a more linear power band thats about the same from idle to 2000rpm where cats seem to really pick up from 1500 to 2000. ya, 425 hp is 425 hp, but thats just a snapshot of one spot in the rpm range.