Cummins ISL 400 versus Maxxforce 10 405 HP

[mike27becky]

We are looking to upgrade from our 2007 Monaco Diplomat 40' with a Cummins 400 ISL engine to a 2012 Holiday Rambler Endeavor 43' tag axle with a Maxxforce 10 (405 HP). Any comments as to the comparison?

[wolfe10]

If you are asking about relative performance and perhaps MPG, first question is what are relative weights of the two coaches?

Clearly there are a lot more Cummins ISL's in motorhomes than Maxxforce 10's, so service MAY be an issue with the Maxxforce (Navistar).

[duanelin]

We went from a 2004 Diplomat 40 ft. with a ISC 330 to a 2012 Diplomat 43ft with the Maxforce 10. Have about 6000 miles on it. It rides and runs better than the 04. The tag axle really make a big difference. Our fuel mileage running 65 on the Interstate is about the same-- about 8.6 mpg.

Duane L

2012 Diplomat 43 DFT

[desertdeals69]

I would consider parts and service availability between the two.

[Traps90]

There's a lot of Navistar Engines in use out there, and getting service and parts is not a problem

[dkreuzen]

Parts and service is definitely not an issue. There are plenty of International Truck dealers around the world. There just are not that many of their engines in Motorhomes.

[ingell@verizon.net]

Mike,

I owned a 2011 Monaco Knight 40 PBQ with the Maxxforce 10 350 HP and now own a 2015 DS 4018 with the Cummins ISL 450 so I can give you some comparisons.

The Navistar motor requires no DEF, it has a EGR system to meet EPA emissions as opposed to the SCR system on the Cummins. Some folks have had some serious problems with this system in the Maxxforce engines but in the 3 years I owned one I never did. Getting one serviced can be a bit more challenging though. Yes there are lots of Navistar service centers out there, however very few will work on motor homes. The Cummins motors are a lot easier to get serviced or repaired in the MH's.

The two MH's in my case had a weight difference of about 10k and a horsepower diff of 100 HP. However they would both pull a steep grade about the same. I would see about 45 MPH on the Siskiyou's between CA and OR on the 6% slopes pulling the same toad. However they have totally different acceleration profiles. The Cummins is much stronger from a stop, the Navistar vehicles just gain momentum, (slowly).

The conventional wisdom about the Navistar motor was to drive it like you stole it. If you did that my coach would get somewhere between 8 and 9 MPG (downhill and with a tailwind maybe 10 mph) I have yet to break 7.5 with the ISL yet,(about 12000 miles so far) but it is a nicer driving powertrain. The Navistar had a 3 stage Jake brake but had a tendency to buck and snort just a bit. The Cummins system is much smoother. There were some software upgrades to the Navistar system that helped but did not provide as well as a behaved system.

Those are the high notes feel free to PM me. By the way I have a spares kit for the Maxxforce.