2014 Mountain Aire Power Problems

[RV4Me4Life]

Originally Posted by Steve Ownby

There is a more scientific way. Find a big Freightliner dealer with a chassis Dyno and schedule a time to have it run on the Dyno. That will tell you all you need to know in no uncertain terms. If it turns up a problem then you will have discovered it in time & warrantee will take care of it. If no problem then you will know that too.

Thank you Steve. I have call Freightliner and they're willing to do exactly this. I'll just need to find the time to get the bus down there and have this accomplished. I will post results. It may not be within the next week but probably after that.

[Steve Ownby]

Originally Posted by RV4Me4Life

Thank you Steve. I have call Freightliner and they're willing to do exactly this. I'll just need to find the time to get the bus down there and have this accomplished. I will post results. It may not be within the next week but probably after that.

I applauded you taking this positive, proactive step. This will provide the answers you need. I'll be very interested in the result. Will be a starting point for many of your fellow owners.

[PDR John]

I agree, the results while be telling.

Very interested in how this will turn out.

[slabman]

Regarding putting a larger engine in the M-A. This summer I traveled through Nova Scotia in my '07 TS Alante, an '07 Mtn. Aire, and another identical Alante. All were 45 ft. Coaches, weighing in around 42k pounds with ISM engines. But while the Alantes were rated at 500 HP, the M-A was at 450 HP. All seemed to pull the hills identically, but the M-A did run the turbo boost up to 37 while both Alantes maxed out at 31. Not sure how to explain this....anyone?

My point is Newmar seems to have always played the de-rate game, likely because of product differentiation even though in this case all engines seemed to perform the same. Fast forward to today and you'll find these beasts have gained lots of weight. My new Essex, for example, is up a whopping 10,000 lbs. from the Alante, yet I'm supposed to have the same HP while torque is up about 50 ft-lbs. I haven't tried to pull any hills yet, so can't comment on performance with this isx.

I compare this to the black tank problem ( don't I always seem to come back to this? :-) ). You can't just make a simple change without thinking about the resulting repercussions it might cause. Can't use more flush water, dumping into the same tank nor can you add weight without adding more power to move it. (Slabman's axiom) LOL!

I doubt they can add power to the M-A without going back to the K-2. If they do, the Dutch is really out of luck. A hefty diet might be the only remaining option. :-(

[zman62]

I compare my 07 monaco camelot with a 400isl to my 14 Entegra Anthem with the 450 isl. They both make the same torque which is what gets us up the hills even though there is 50 more horses. The Anthem feels a lot more powerful than my Camelot. I notice the the Camelot and the MA run the same rearend gear. The Anthem is running a shorter gear which is why it has plenty of power. My opinion is they are using too tall of a gear in the MA.

[HHIDan]

Originally Posted by RV4Me4Life

Thank you Steve. I have call Freightliner and they're willing to do exactly this. I'll just need to find the time to get the bus down there and have this accomplished. I will post results. It may not be within the next week but probably after that.

I'm anxious to see the results here as well. I only wish there were a "few" coaches being tested, for instance pre and post emission (DEF).

And a question if I may. When they measure torque on a dyno, are they shifting the transmission electronically? ie Is torque the same at 1200rpm in 3rd gear as it is at 1200rpm in 2nd gear?

And a comment, I often hear about the differential gearing playing an important role in the torque produced. There is a compromise here that the manufacturer is making.

[Sky_Boss]

Originally Posted by HHIDan

...
And a comment, I often hear about the differential gearing playing an important role in the torque produced. There is a compromise here that the manufacturer is making.

An interesting point here. Are manufacturers opting to use gearing to improve overall MPG at the expense of hill climbing performance? It would be an interesting debate on which grabs an owners attention the most. Constantly burning more fuel or occasionally (relatively speaking for many of us flatlanders) going slower up big hills. I realize west coasters might have a totally different view of this.

[PushedAround]

I thought that is what the 6 speed transmissions were for. My MT2500 runs at 1650 rpm at 65 in 6th, but then increases to 1900 in 5th at the same speed. That is a 13% change, much greater than the Mountainaire 4.63 vs the Anthem 4.88 gearing. Unless the climb becomes significant, it seems to be able to hold pace in 5th.

[HHIDan]

Originally Posted by Sky_Boss

An interesting point here. Are manufacturers opting to use gearing to improve overall MPG at the expense of hill climbing performance? It would be an interesting debate on which grabs an owners attention the most. Constantly burning more fuel or occasionally (relatively speaking for many of us flatlanders) going slower up big hills. I realize west coasters might have a totally different view of this.

I believe, from my limited knowledge, that a 2 speed differential would be a nice feature in our heavy motorhomes. 1 speed/gearing for highway (MPG-economy) and the other speed for climbing. I'm told it's about a $10K feature. Take a while to recover the fuel economy... Pretty much everything in life has to do with compromises!

[PDR John]

It will be interesting to find the out come.

Is there an incoming air restriction? As is: wrong air filter, pinched tube or blocked pipe.

Is there an exhaust restriction? Somebody kinked the pipe making bends.

Is it a gearing issue?

What does the coach weigh?

We went from a 38' 32,000# coach with a 330 hp 850 ft lbs Cat 3126 to a 43' 44,000# coach with a 450 hp 1250 ft lbs Cummins ISL and our hill climbing stayed the same. We're in the hills a lot.

If there is some improvement I'd like to know.

[hoosier1]

Originally Posted by RV4Me4Life

Thank you Steve. I have call Freightliner and they're willing to do exactly this. I'll just need to find the time to get the bus down there and have this accomplished. I will post results. It may not be within the next week but probably after that.

I use to own a 2007 Newmar MA and had the same problem climbing hills. When I was at Spartan I talked to the Cummins person there about my problem. He found that the fresh air pipe from up above was not fitting tight to the air filter and was allowing hot engine air back into the engine. They called Newmar which fixed it. After they put new packing in I did not have any more problems.

John

[Sky_Boss]

Originally Posted by PDR John

...
We went from a 38' 32,000# coach with a 330 hp 850 ft lbs Cat 3126 to a 43' 44,000# coach with a 450 hp 1250 ft lbs Cummins ISL and our hill climbing stayed the same. ...

A couple interesting points here. You stayed pretty close to the 1 HP per 100# of coach weight. The other thing is the CAT vs Cummins torque numbers. When doing my research for my DSDP I was looking at the torque differences. I don't have any of the info anymore but when I did that research I think I saw that while the Cummins specs out with higher torque than the CAT, once you got to typical cruise RPM they had similar torque performance. Yes, down low the Cummins was stronger but I wasn't looking for a drag racer either. LOL

Anyway...if I have pieced this torque vs horsepower stuff together correctly, at hill climbing settings the CAT and Cummins torque values would be pretty close to each other. That along with the similar HP to weight ratio seems to be a reasonable THEORY why you aren't seeing much of a change in that area. Of course, I don't know the full gearing comparison between them and that could account for a lot of how they compare to each other.

[Steve Ownby]

Originally Posted by PDR John

It will be interesting to find the out come. Is there an incoming air restriction? As is: wrong air filter, pinched tube or blocked pipe. Is there an exhaust restriction? Somebody kinked the pipe making bends. Is it a gearing issue? What does the coach weigh? We went from a 38' 32,000# coach with a 330 hp 850 ft lbs Cat 3126 to a 43' 44,000# coach with a 450 hp 1250 ft lbs Cummins ISL and our hill climbing stayed the same. We're in the hills a lot. If there is some improvement I'd like to know.

For the most part the coach builders use power as a sales tool within certain parameters. In midrange DPs the ISL in all it's many ratings has been the favorite over the last 10 years. The effects of the '07 EPA requirements really hurt power as the EGR valve that was used pretty much across the boards was much worse than the DPF from a power standpoint. With the EPA 2010 requirements & the advent of DEF, the EGR was detuned so it's not as big a power drain as the NOX reduction was moved outside the engine. That is the reason the ISL is now rated at 450 hp.

Cummins dropping the ISM from production was a blow to coach builders as it was a perfect step up from the ISL. The Cummins ISX12 is rated at the same 500 hp as the ISM but with 100 more lb/ft of torque. The unfortunate part is that the ISX12 & ISX15 are really heavy and stress the rear suspension & chassis of a coach.

The use of the Cummins ISX15 is the place that the coach builders step out of the equation and put high performance in a coach.

I suspect, in the case of the coaches being discussed here, the intake system may be marginal but within Cummins specs. The gearing may be somewhat tall for the power/torque curve of the engine, but the main difficulty is the weight of the coach. When you get up to and over that 100 pounds of rolling weight per hp then just driving with the right foot yields poor results. It becomes increasingly important to keep the rpm level up close to the hp peak while climbing. This requires manual shifting as the Allison programming will not shift soon enough and will get behind the power curve & can't recover.

[PDR John]

Originally Posted by Sky_Boss

A couple interesting points here. You stayed pretty close to the 1 HP per 100# of coach weight. The other thing is the CAT vs Cummins torque numbers. When doing my research for my DSDP I was looking at the torque differences. I don't have any of the info anymore but when I did that research I think I saw that while the Cummins specs out with higher torque than the CAT, once you got to typical cruise RPM they had similar torque performance. Yes, down low the Cummins was stronger but I wasn't looking for a drag racer either. LOL

Anyway...if I have pieced this torque vs horsepower stuff together correctly, at hill climbing settings the CAT and Cummins torque values would be pretty close to each other. That along with the similar HP to weight ratio seems to be a reasonable THEORY why you aren't seeing much of a change in that area. Of course, I don't know the full gearing comparison between them and that could account for a lot of how they compare to each other.

At one time I know the gear ratio for both. I'll do some digging and see what I come up with.

Both coaches are running down the road at 1750 RPM.

I'm curious what his weight is, seeing how we have the same axle weight rating, engine, trans and frame.

Front 17,000# rear 20,000# tag 10,000#

My point of view is from a different place, I jumped a size where he moved over.