What drive train?

[Gary RV_Wizard]

Just don’t get caught up conflating HP with Torque. All other things being equal a 360 HP diesel firing off compression with longer stroke is going to produce more torque than a 360 HP gas engine sparking the chamber with a shorter stroke, ie., the diesel is going to turn the crankshaft with more rotational force ( torque).

Furthermore, no one in the history of motorhomes ever said, “I wish I’d bought a gasser instead of this DP we settled for”.

The value of the higher diesel torque is that you get all that horsepower at low RPMs - you don't have to wait until the engine is screaming to get the peak power. Torque x RPM is what produces HP.

To cite an example that has actual spec data available, a Cummins 6.0L 6 cyclinder diesel produces 340 hp at 2700 rpms with 660 lb-ft of torque. The GM 8.1L V8 produces 340 hp at 4200 rpms with 455 lb-ft of torque. The bigger 8.3L and 8.9L diesels show an even greater rpm advantage because of their still higher torque.

 

[Onyrlef]

Actually H=TxRPM/5252. The diesel producing greater rotational force (torque) at the crank shaft at lower rpm is the point and ipso facto why a 360 HP gas chassis RV and a 360 HP diesel chassis RV are not even remotely the same animal and especially considering a class A/C RV is always towing something,…..itself. It’s a self propelled house. For the OP that’s specifically why he should be aware that shopping for RV’s based on HP alone could land you with a rig that won’t get out of it’s own way when at it’s gcvwr.

 

[oldwildman]

Actually H=TxRPM/5252. The diesel producing greater rotational force (torque) at the crank shaft at lower rpm is the point and ipso facto why a 360 HP gas chassis RV and a 360 HP diesel chassis RV are not even remotely the same animal and especially considering a class A/C RV is always towing something,…..itself. It’s a self propelled house. For the OP that’s specifically why he should be aware that shopping for RV’s based on HP alone could land you with a rig that won’t get out of it’s own way when at it’s gcvwr.

I understand the torque thing better now. Was always a little vague. What it boils down to I guess is greater power at lower rpms. I'm almost certainly going with the larger diesel. I hate hearing a motor scream. Always waiting for pistons and rods to come flying through the hood!

 

[Onyrlef]

I understand the torque thing better now. Was always a little vague. What it boils down to I guess is greater power at lower rpms. I'm almost certainly going with the larger diesel. I hate hearing a motor scream. Always waiting for pistons and rods to come flying through the hood!

It will all be relative to what you expect to be doing. I am in a 32’ 23k GCVWR F53 chassis with a 3 valve Triton V10 and 5 spd torqshift Tran. I tow 6k at most but don’t venture out far or for long, so a DP would be redundant on my case. Were I planning to be doing a lot of traveling, towing a lot, and living in the coach for extended periods I might prefer something different.

 

[oldwildman]

Sounds like you are in the perfect financial place to do Rving.

I (personally) am happy you don't have to (and won't) get a huge loan to go adventuring. Sounds like the worst thing that can happen is Deb pulls the pin in 6 months and you lose some taxes, registration and a few other things financially.

" And we're pretty flexible on models at this point. While there are features that we'd really like to have, we can live without most."

Well now you brought that up, and considering your picture here are some real considerations based on things I missed or deemed necessary.

1 - Bigger shower is better
2 - Consider counterspace - Doing meal prep on the dinette or with a plug in the sink becomes a PITA
3 - variety of seating areas and visibility to the tv. I mounted my tv on a swing mount visible from the couch or the dinette - nice to watch news in the morning while eating breakfast.
4 - I stayed primarily in parks long term. I always wanted a washer dryer. Communal laundry went out of my life after college. It was tough to go back.
5 - In your size do not even consider a solo air conditioner.
6 - Personally would not settle on an AC only fridge. Propane makes so much sense while traveling and the occasional boondock/overnight.
7 - Likewise I would not settle on a propane only water heater - AC/propane is my choice.
8 - Don't even consider a non-walkaround bed...
9 - Consider where you will have a computer station - it gets old quick (IMO) to use the dinette for computing and have to put things up to eat. I got rid of a single recliner chair and built a folding workstation. It was proximate to the TV so I could technically dual screen the laptop.

All good stuff. Thanks! Never did like loans, especially on a depreciating asset. I've always been a big fan of collecting interest, not paying it. Sadly, I haven't been able to pass that on to the kids.
:-(

I wasn't aware of the choices re propane vs AC. I assume that means I can use the appliances, hot water and frig, without the generator running?

Deb rented us an airstream trailer for a long weekend two years ago to try the whole idea out. 24-25 ft, I think. No slides, don't even think they have them. That curved roof really makes things claustrophobic. And it didn't have a walkaround bed. At our age, just rolling off the side is bad enough. Amazing what a difference that simple thing makes. Yep, walkaround bed is a necessity.

We've seen units with a washer dryer in one appliance. Not sure how the dryer would work. And we heard the capacity is really small. Considering getting a small residential stackable and installing that in an appropriate spot. I realize the water usage would limit it to being used when fully hooked up at a campground. Is that feasible? I'm a very experienced contractor/jack of all trades who enjoys difficult projects. Once built a dumbwaiter (with safety interlocks) for a cooking school out of a garage door opener. The off the shelf ones were very expensive. 10+ years later it's still going strong. I googled the weight of a typical stackable and, empty, it tips the scales at about 270#.

We were discussing computer space. A folding workstation is a great idea. Thanks!

Counterspace is going to be a serious consideration. We both like to cook. In the pics, I've seen several ways the manufacturers deal with that. Will have a better opinion when we start seeing them in person. We realize that the kitchens are very small but we'll manage.

Thanks again!

 

[Larry N.]

I wasn't aware of the choices re propane vs AC. I assume that means I can use the appliances, hot water and frig, without the generator running?

So much depends on what you have in the rig. A typical "RV" fridge (absorption type) is usually run from either propane or 120 VAC, along with 12 VDC for the control board, but many of the larger rigs have gone to residential refrigerators, so must run from 120 VAC. My last two rigs (a Beaver and a Ventana) have had residential refrigerators but also have had a 2000+ watt inverter to run it from batteries, along with a much larger battery bank (house) than otherwise would be there. Worked great for overnight without hookups. While my Beaver had a propane stove, my Ventana had an electric induction stove, needing steel in the pans for heating, so we usually ran the generator when it was time to cook. Both rigs had combo microwave/convection ovens which work pretty well -- wife made pineapple upside down cakes, biscuits, roasts and more in them.

In both diesel rigs the hot water and furnace heat were from hydronic systems (Aqua Hot and Oasis, respectively), with primary heat being from a diesel burner and secondary from 120 VAC electric heating for the boiler. Often, when you have hookups, the electric part is sufficient. They are also a lot quieter (not silent, though) than the propane furnaces, and provide more even heat too.

My first class A was a gasoline Bounder using the Ford V10 and had the typical "RV" type fridge, as well as two propane furnaces and a propane/electric water heater. The "screaming" engine of the V10, which gets best power at over 4,000 RPM, is annoying and loud, but the engine is nearly bullet proof and is made to run that way- nonetheless, this mostly happens when climbing the steeper hills, especially when you must hit the lower gears.

Considering getting a small residential stackable and installing that in an appropriate spot. I realize the water usage would limit it to being used when fully hooked up at a campground. Is that feasible?

In both diesel rigs (but not in the Bounder) we also had the small stackable washer/dryer and they were great. You could probably run the washer for one or two loads while drawing only from the onboard tank, but water capacity for other uses would be very limited indeed. Gray tank capacity must also be considered, of course. And to run the dryer you must have either shore power or run the generator.

Be aware, too, that an uneven load in the washer can shake the whole coach a lot during spin cycles, though there will be a little shaking even with a balanced load. It's just the nature of the beast. You probably won't want to run them while on the road.

Hope this helps.

 

[Ex-Calif]

We were discussing computer space. A folding workstation is a great idea. Thanks!

Here are a couple shots of my workstation. Note the TV mount I also tied into the aluminum frames of the door and window. In the third phot you can see the "comfy" chair I pulled out.

I eventually mounted a 400W inverter here that would run the laptop, wifi router and tv off battery power if needed.

In regards to the washer - I did a design where I would pull the vanity sink, Install a combo washer/dryer and raise the sink to clear it. Never got that far on the project list.

If you have space a stackable would be better but the combo units do pretty well, especially if you can vent overboard. You definitely are limited to smaller loads but that's OK when on the road. Bedding is probably a laundromat visit for sure.

 

[oldwildman]

Thanks for the pics! I'm definitely going to steal that idea.

 

[Kirk]

I wasn't aware of the choices re propane vs AC. I assume that means I can use the appliances, hot water and frig, without the generator running?

In the typical used RV, the water heater will heat with propane and possibly have 120V as well. It will still require 12V-dc power as that is what the controls use but only a very small amount. RV absorption refrigerators also the option of using either 120V or propane but they too need a small amount of 12V for the control circuits. You may find RVs that have a house type refrigerator and those typically have an inverter to supply them when not on 120V. If that is the case then you will also need more batteries to support it when dry camping. Things like the lights furnace blower, water pump and most appliances are powered by 12V so that they work without 120V supply. The exception will be the microwave and most of the TV sets.

Will have a better opinion when we start seeing them in person.

I suggest that if you can find a large RV show to visit, that would be a good way to start as it will allow you to see many different makes and models in one place to compare. Even though they will all be new RVs, its the very best way to see what the options are in a relatively short period of time.

 

[Gary RV_Wizard]

I understand the torque thing better now. Was always a little vague. What it boils down to I guess is greater power at lower rpms. I'm almost certainly going with the larger diesel. I hate hearing a motor scream. Always waiting for pistons and rods to come flying through the hood!

Just be aware that "screaming" is also relative to engine type. A diesel with its heavy pistons and rods is incapable of high rpms, so most mid-size diesels max out (red line) at around 2200-2800 rpms. So the mechanical scream simply comes at a much lower rpm number than a gas engine of similar Hp.

No motorhome is powered enough to have more than "stately" performance, but a diesel will do it without a lot of fuss.

 

[oldwildman]

In the typical used RV, the water heater will heat with propane and possibly have 120V as well. It will still require 12V-dc power as that is what the controls use but only a very small amount. RV absorption refrigerators also the option of using either 120V or propane but they too need a small amount of 12V for the control circuits. You may find RVs that have a house type refrigerator and those typically have an inverter to supply them when not on 120V. If that is the case then you will also need more batteries to support it when dry camping. Things like the lights furnace blower, water pump and most appliances are powered by 12V so that they work without 120V supply. The exception will be the microwave and most of the TV sets.

I suggest that if you can find a large RV show to visit, that would be a good way to start as it will allow you to see many different makes and models in one place to compare. Even though they will all be new RVs, its the very best way to see what the options are in a relatively short period of time.

Thanks, that makes sense. We were wondering how things worked with AC, 12v and propane on the same coach. Now we have a better idea.

We've gone to the RV show here in town. However, it's mostly campers and trailers. Some similarities but not exactly the same. We are going to go to all the nearby dealers this summer and let them educate us. We won't be buying until next year, though. And almost certainly from a private party.

 

[oldwildman]

Just be aware that "screaming" is also relative to engine type. A diesel with its heavy pistons and rods is incapable of high rpms, so most mid-size diesels max out (red line) at around 2200-2800 rpms. So the mechanical scream simply comes at a much lower rpm number than a gas engine of similar Hp.

No motorhome is powered enough to have more than "stately" performance, but a diesel will do it without a lot of fuss.

Stately? I like it! Sounds better than slow. Less fuss sounds good.

 

[Onyrlef]

The notion that a diesel needs to scream like a gas burner to produce an equivalent amount of torque is not entirely accurate, regardless the rpm. The reason a gas burner has to go to defcon five to produce the equivalent torque is it has to spin the drive shaft at a much greater rpm, it must work faster and louder and will have a shorter life. Using watts as a constant measure of power ( work) a randomly selected simple 52/17, gear ratio turning @ 50 rpm and a 42/17 gear ratio turning at 100 rpm are producing the same number of watts, ie., producing the same amount of work. All other things being equal they may climb a 6% grade at the same rate but once the weaker of the two (42/17), changes gears out of necessity to a 52/11 ( 0% grade) and the other changes to the same 52/11, the one who out of necessity had to climb in the 42/17 just to keep up is history, only because he can't produce sufficient torque in that range without going back to defcon 5.

 

[Gary RV_Wizard]

I am using "scream" to mean "operating near the rpm redline" as opposed to literal decibels of sound. An engine operating near or at its rpm peak is working hard, regardless of the term describing that.

That said, diesels are of necessity more ruggedly built so as to handle their much higher compressions (around 17:1-19:1), and that combined with lower rpms reduces wear & tear considerably. That's why a motorhome diesel is expected to go 500k+ miles between rebuilds vs around 250k for a big-block gas engine.

 

[Kirk]

We were wondering how things worked with AC, 12v and propane on the same coach.

The things that require most electricity power are 120V only and can be used when powered by outside electrical connections or from an onboard generator. Most motorhomes today have either a generator or the option to have one that can be used whether driving or parked if you need 120V and it isn't available from outside. Some also have an inverter, which can make 120V from the 12V supplied by batteries or the alternator, but they usually are limited in what you can power from one because of the limited supply from the batteries.

There are two 12V-direct current systems in a motorhome. One is the same as found in any automobile and supplies things like the starter, heatlights, and associated items. The second is for the coach appliances and lights and it will have batteries, and a converter that takes 120V-alternating current and converts it into 12V-direct current to recharge the coach batteries and supply the coach loads. The supply to that converter can be either from shore power or from an onboard generator. The chassis alternator can also supply the coach 12V system when traveling. To better understand the coach electrical system, I suggest that you read The 12V Side of Life parts 1 and 2. Below is a picture of a typical RV fresh water system.
\

 

[oldwildman]

I am using "scream" to mean "operating near the rpm redline" as opposed to literal decibels of sound. An engine operating near or at its rpm peak is working hard, regardless of the term describing that.

That said, diesels are of necessity more ruggedly built so as to handle their much higher compressions (around 17:1-19:1), and that combined with lower rpms reduces wear & tear considerably. That's why a motorhome diesel is expected to go 500k+ miles between rebuilds vs around 250k for a big-block gas engine.

Thanks for the rpm/torque explanations. Deb is now fully onboard with getting diesel if at all possible. We were in the car and I ran it at 2700 rpm for a distance and then at 4500 rpm for a distance. Told her that that's what would be happening on a long hill climb. Yes, I know there are differences in diesel sound vs gas. But she knows what having the motor up front sounds like because she's rode in my work truck, a Chevy Express cutaway. Gotta keep the boss onboard with these decisions.

 

[oldwildman]

The things that require most electricity power are 120V only and can be used when powered by outside electrical connections or from an onboard generator. Most motorhomes today have either a generator or the option to have one that can be used whether driving or parked if you need 120V and it isn't available from outside. Some also have an inverter, which can make 120V from the 12V supplied by batteries or the alternator, but they usually are limited in what you can power from one because of the limited supply from the batteries.

There are two 12V-direct current systems in a motorhome. One is the same as found in any automobile and supplies things like the starter, heatlights, and associated items. The second is for the coach appliances and lights and it will have batteries, and a converter that takes 120V-alternating current and converts it into 12V-direct current to recharge the coach batteries and supply the coach loads. The supply to that converter can be either from shore power or from an onboard generator. The chassis alternator can also supply the coach 12V system when traveling. To better understand the coach electrical system, I suggest that you read The 12V Side of Life parts 1 and 2. Below is a picture of a typical RV fresh water system.
View attachment 171385\

Ah, I wondered how the system dealt with city water pressure vs pump. I didn't think the storage tank was pressurized but wasn't sure how that was handled. I'm assuming there's a one way valve in the pump. Very simple solution. I took a quick look at the electrical link. Thanks! That will keep me busy and off the streets for a bit! LOL

 

[Gary RV_Wizard]

Yes, the pump acts as a check valve. For that reason, many systems have a bypass around the pump to allow the city inlet side to feed water to the fresh tank (not shown in that diagram). The city inlet also has a check valve which prevents the pump from pushing water out of the system thru the city inlet. In essence, the city (hose) source and the water pump are in parallel and if both are active the flow through the RV system is in proportion to the pressure of each source. An RV water pump is usually factory preset to 45 psi but many owners operate them somewhat higher, e.g. 50-55 psi. City inlet pressure is all over the map, anywhere from 20 to as much as a crazy 100 psi. If there is any chance of encountering a 100 psi city source, use an external regulator to hold the pressure down below 60-65 psi.

 

[Chef Duane]

Karmann Ghia is a VW, both had rear mounted air cooled engines.

IIRC KG was the coach designer & manufacturer while VW did the chassis and powertrain. Kinda' like when Chevelles used to have that entry plate that said "Body by Fisher." But yes, when someone thinks of a Karmann-Ghia they think Volkswagen. My brother's girlfriend had a red convertible KG.

See info under "Genesis":

Volkswagen Karmann Ghia - Wikipedia

en.wikipedia.org

Fisher Body - Wikipedia

en.wikipedia.org