Can anyone give me rough idea of how - say a 5 year old Super C with a 300 hp Duramax/Allison would drive and tow 5,000 lbs compared to a 10 year old 8.3 330 hp diesel pusher? I'm thinking handling, comfort, quiet etc.
Well the Super C is built on a truck chassis, while the DP will have a larger displacement inline 6, that should last longer than the V8 diesel, and the transmission is a little larger as well.
The V8 will be much easier to work on, and not put the mechanics in your bedroom.
The DP will normally have air ride suspension, and that is difficult to compare to steel springs. If it has air brakes, those are different. Not really more difficult to use or something, but different. With air brakes you are just pressing the pedal to release air pressure, and take you foot off the pedal to add air to the system, and release the brake pad springs. (the springs apply brake pressure when there is not air pressure, so if there is a air line break, then the brakes will apply with the fullest force possible.)
The DP will normally have a engine brake - at least on the higher end units.
I know someone who was thinking of selling his Country Coach for about $90,000. It only had one slide, and was 40' with engine brake, and all that stuff. He ended up donating it instead.
I think I would be tempted to pick the 5 year older Country Coach over a slightly newer Super C if the prices where close. But also use care that some RV parks have strict rules about letting in units over 12 years old.
You are looking at two completely different motorhome size classes, not just different configurations.
A DP with a Cummins 8.3 will usually be around 34,000 GVWR and 38 to 40 feet of house, if not longer. It will have air suspension, air brakes, and the engine will be located where you don't hear it quite so much. You will sit forward of the front axle, where the ride will be much less harsh (on air springs vs steel) and might be bouncier (leverage, sitting outside the wheel base). You will have a big window in front of you. The Allison transmission will be a heavier-duty version. The engine will be tuned to cruise at about 1200 RPM, make peak power around 1800.
A Duramax/Allison Super-C means Kodiak, a class 5 medium truck chassis on steel springs, 19,000 to 22,000 GVWR, with a lighter-duty 1000 series or 2000 series Allison transmission. On this chassis, motorhomes are built in the 32 to 38 foot range, meaning 24 to 30 foot of house behind the cab. You will sit just behind the engine, on top of the transmission, where you can hear what both are doing. The engine will be tuned to cruise around 1600-2000 rpm with peak power around 3000.
That stuff about how the air brake works is wrong: that describes the Westinghouse brake used on trains in the late 19th century. The air brake on a modern truck, bus, or motorhome, is applied actively by air pressure, in proportion to how far you push the pedal, just like the vacuum assisted hydraulic brake in a car.
The DP motorhome most comparable to a Kodiak-based Super-C would be the diesel Holiday Rambler Vacationer or Monaco LaPalma, about 24,000 GVWR on a leaf spring chassis, with 5.9 or 6.7 Cummins, comparable torque, power and speeds to the Duramax, using the same light-duty Allison. You will find these in lengths comparable to Super-C, but even this size motorhome gives you eight foot of house that you lose to the cab of a Super-C.
If you want to compare a DP with 8.3 Cummins to some type of C, the more likely comparison would be a Dynaquest C on a Class 6 Freightliner with the 8-liter M-B diesel.
Take both on a VERY long test drive and be sure to travel on every type of road and terrain. A 5K trailer should not be the issue for either. You will probably come back from the test drives loving one and hating the other as they are in no way similar. Also check your state as some states require a higher class license for vehicles over 26,000 lb GCWR.
"That stuff about how the air brake works is wrong: that describes the Westinghouse brake used on trains in the late 19th century. The air brake on a modern truck, bus, or motorhome, is applied actively by air pressure, in proportion to how far you push the pedal, just like the vacuum assisted hydraulic brake in a car."
"tatest" Hate to tell you that you have it wrong. Today's over the road trucks as well as firetrucks, dump trucks, etc are spring loaded and when the air is removed the brakes are applied. If you loose air, the brakes lock up. Managed a fleet for 15 years.
RIGHT OFF OF HOW STUFF WORKS:
1.Charging: The system must be pressurized with air before the brakes will release. At rest, the brakes remain engaged. Once the system reaches its operating pressure, the brakes are freed and ready to use.
2.Applying: As the brakes are applied, air pressure decreases. As the amount of air decreases, the valve allows air back into the reservoir tanks, while the brakes move to the applied position.
3.Releasing: Once the brakes are applied and the air escapes after braking, the increased pressure releases the brakes.
Grandma in front of her retirement home..
She lets Grumpy drive!!