340 ISB power

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JD Sharp

JD Sharp

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Joined
Jun 20, 2009
Posts
247
Location
Ferndale, WA
Still in search for motorhome and have question about Cummins 340hp 660 ft-lbs. ISB. We are looking at 2012 Tiffin Red's and see they use same engine in 34ft model as in 39ft model. All are rated at 29,500 GVWR and 5000 towing, how can that be? I am concerned the 38QRA is under powered when fully loaded and towed is hook up. We travel mainly in western states with lots of 6% grades.
 
29,500# and towing 5000# is the same weight regardless if the coach is 34' or 39'. Weight is weight. I would be more concerned with the difference of OCC than the power.
 
I am concerned the 38QRA is under powered when fully loaded and towed is hook up.
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I'd be more inclined to think (if they were loaded according to length) that the 34' unit would be more lively, but by gross weight they are about 85 lbs/HP, where so many units tend to be closer to 100 lbs/HP, so I doubt it'll be a problem.

As for the same engine and weight, that's probably because they are essentially the same chassis, just with an extension on the longer unit.
 
Check the CCC for the 34 ft. vs. 39 ft.  Both have a maximum weight limit (GVWR) of 29,000 lbs, but chances are the shorter rig weighs less empty and thus has more CCC than the longer one.
 
Where can I find CCC or Curb Weight or Net Weight? Nice to have a bigger motorhome but not if I cant put much in it. Also I noticed Tiffin in 2017 changed ISB engine to one with to 360 HP and 800 ft-lbs.
 
Tiffin didn't really upgrade the power - the ISB they use just got more powerful as years progressed.

The GVWR for the chassis is fixed by the chassis builder, but the actual weight with coach body on it varies with the body style, floor plan, equipment (std or opt), etc.  Thus it is individual to each specific coach and shown on a federally-required label on the interior wall by  the driver seat.  Snap a photo of each you see when shopping, so you can compare them later.

In all likelihood the 34 footer will be somewhat lighter as built and therefore have more cargo capacity and perform a bit more lively, but I would not conclude the longer models are poor performers or very low CCC.  You are wise to check that, however, and recording that info should be a standard part of inspecting any rig that you are considering. It's a key factor in your decision.
 
Actually Freightliner offers six differenet ISB's rated at 300 - 360 hp / 224 - 268 kW, 660 - 800 lb-ft / 895 - 1085 N?m for motorhomes in 2018, so Tiffin could have kept 340 hp.
 
Just got CCC (cargo carrying capacity) for 39ft and it is 2360 lbs. Doesn't sound like much to me, what do you all think?
 
There's no question the dry weight of a manufacturers 39 foot model will weigh more than their 34 foot model if both chassis have the same GVWR.  Our 2005 35.6 foot Pace Arrow weighs 900 lbs less than the 37.8 foot model.  If your carrying capacity is in addition to fuel, water and propane, then it's not bad for a gasser.  If you have to reduce it by water, gas and propane, you're net capacity will be significantly less. 
 
2360 isn't terrible, but it's not a lot either.  38-40 ft coaches usually have 3000+ and the better rigs will be 5000 or more.

Without meaning to knock your choice of coach, the Red is a bargain basement DP.  It gives a lot of bang for the buck, but it's not in the same league as rigs costing $25-$50k more, e.g. the Phaeton.  If you want a larger coach but are are worried about insufficient engine performance, CCC, and other capabilities, you might want to set your sights a little higher in the spectrum of DP models.  Or stick with the 34 footer.
 
We looked at the current Reds and the larger ones are short on rear axle payload, at least for our needs as a full timer. The shorter model, the 33AA, has sufficient payload but we don?t like the layout.

I think the ceramic tile floor of the Red is a false luxury that harms the usefulness of the rig by robbing payload. Note that to save weight over the rear axle the bedrooms have carpeted floors and the mix of ceramic tile with carpet looks bad; better to have done the entire coach in vinyl tile, as with the gassers. Then the Red would gain payload and have a consistent look front to rear.
 
More buyers look at styling and features than carrying capacity and drivability, so that (and price) is what the RV makers cater to in their entry-level configurations.  They have other models for those who want more and are prepared to pay for it.

There is no free lunch - if you want a bigger rig and still have plenty of cargo capacity and performance, you have to spend more to get a chassis that has the capability to do that.
 
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