40' Newmar 400HP vs 370HP Cummins

USMC46 wrote:
We have a 2004 Dutch Star Model 4025 with the ISL 370. We head to the mountains every year pulling a Jeep Liberty, and have never had a problem. The mileage is good and it's just an overall great unit. It's my first and only coach, so I can not compare it with others. We may be seling ours as some health issues are going to limit the travel and I can't stand to see it parked. You cannot go wrong with the Newmar product, in my opinion. We LOVE ours.

I am running the ISC 360 HP I travel the hills of W. Virginia and Virgina all the time 7 percent grades for miles . I pass trucks but will admit I do seem to top out at 45-50 going up the most severe grades , but to me it isn't a major deal I drive flat land 80 percent of the4 time and the milage I get is way way better than a bigger engine would get .

I am satified with the 360 ISC also . Love our Newmar also, after 3 others it is the nicest we have had

If these were both 8.9L engines and in the same coach, you would be hard pressed to tell any difference. The bigger HP motor in a bigger, heavier coach may not perform as well as the smaller engine in a lighter rig. They are both very good motors and you couldn't go wrong with either choice.

Way too many variables here and IMHO you would be best served buying the coach that has the floor plan that you and your wife like the best and whichever engine it comes with.....so be it. If you "settle" for living features to get a certain engine, you may be wanting to trade sooner than expected.

We have a 2004 Dutch Star Model 4025 with the ISL 370. We head to the mountains every year pulling a Jeep Liberty, and have never had a problem. The mileage is good and it's just an overall great unit. It's my first and only coach, so I can not compare it with others. We may be seling ours as some health issues are going to limit the travel and I can't stand to see it parked. You cannot go wrong with the Newmar product, in my opinion. We LOVE ours.

You might also want to check whether each engine has an engine brake, exhaust brake, etc. The ISL generally can have a 2-stage engine brake, but I'm not sure that all do. I would say it's critical to have one or the other, but I don't think the difference between the two would be a deal-breaker.

wolfe10 wrote:
I suspect BOTH are the 8.9 liter ISL engine. It could be had in either 370 or 400 HP and with exhaust brake or engine compression brake.

Indeed they are the same engine, the 8.9 ISL. The 400 HP has been reprogrammed to produce more power, but both are still rated at 1200 ft-lb torque.

A friend with the same model coach as mine had Cummins reprogram his 370 to 400. He could perceive no change in performance.

Our 2004 is 370 ISL and absolutely no problems in mountains. Your perhpas future 400 shouldn't have any different maintenance issues and 'probably' no mileage difference. It would probably have a little more oomph on the hills. Enjoy the Newmar! We certainly do!!

I suspect BOTH are the 8.9 liter ISL engine. It could be had in either 370 or 400 HP and with exhaust brake or engine compression brake.

I agree, you are very unlikely to notice a 30 HP difference if on the same engine. If comparing an 8.3 with a 8.9, there will also be a torque difference.

I've got a 2004 DutchStar (4010) and love it. We bought it new and have taken good care of it. It has a 370 I.S.L. Cummins. We've been around the country 3 times and she has handled everything.....towing a Honda CRY. Mountains out West never a problem. I am sure you will do fine with either one.

Best guess, you will never notice the difference. Perhaps if one of each were drag racing up a hill, the higher HP might pull ahead but only if the weights were the same.

Go for whichever one you like the best and don't obsess about the HP. This is the smallest consideration when buying a MH unless you will do nothing but go uphill. Fuel economy, in reality, is also a non issue. Really, who care if one get better or worse mileage as they will all be withing 1/2 mpg and that is a very minor difference in a trip cost.

You would be amazed at how many folks don't even bother checking the fuel economy cause it just doesn't matter. Like someone on this forum said: "If you have to worry about the fuel, you shouldn't buy it"

The 400 is most likely a ISL 8.9 engine, 1200 lbs of torque. The 370 might be a ISC 8.3, 1050 lbs of torque. That's where you would feel the difference.