Community Forums

rough road · 12-04-2011, 12:17 PM

apairajays, the only way to know for certain what mileage you are getting is to fill to a visible level in the neck, drive and then refill to that level. Checking mgp this way is 100% accurate whether one drives 100 miles or 100,000 miles; the only variable would be over the mechanical lifetime of the engine as fuel consumption might be affected by a break in period and this I think would only be applicable to larger engines.
For instance, of the six or so diesel cars and light trucks we have owned not one got any better mileage during the time we owned them, the mileage new was the mileage at sale; but all of the large tank trucks we operated did return somewhat better mileage after approximately 20k miles.

I think that generally anyone with a class A who claims to get over the high single numbers is telling a tall tale OR they are operating on flat roads for hundreds of miles at 1000 revs or the calculation is flawed. The biggest error is operating in very hot climates and refilling at less than an amount which would chill the expanded fuel in the tank thus dramatically skewing the numbers.

Don't get me wrong, I am certain they THINK that they are getting the numbers they report but....

sparkydog · 12-04-2011, 12:17 PM

We did the boating thing as well, but love our MH. 45' HR Imperial with 425 ISL Cummins, 7.6 mpg towing.

Pairajays · 12-04-2011, 01:44 PM

Quote:

Originally Posted by rough road

apairajays, the only way to know for certain what mileage you are getting is to fill to a visible level in the neck, drive and then refill to that level. Checking mgp this way is 100% accurate whether one drives 100 miles or 100,000 miles; the only variable would be over the mechanical lifetime of the engine as fuel consumption might be affected by a break in period and this I think would only be applicable to larger engines.
For instance, of the six or so diesel cars and light trucks we have owned not one got any better mileage during the time we owned them, the mileage new was the mileage at sale; but all of the large tank trucks we operated did return somewhat better mileage after approximately 20k miles.

I think that generally anyone with a class A who claims to get over the high single numbers is telling a tall tale OR they are operating on flat roads for hundreds of miles at 1000 revs or the calculation is flawed. The biggest error is operating in very hot climates and refilling at less than an amount which would chill the expanded fuel in the tank thus dramatically skewing the numbers.

Don't get me wrong, I am certain they THINK that they are getting the numbers they report but....

I agree and that's my point, it is very difficult to fill the fuel tank, on a MH, to the exact same level each time. The fill spout to the tank is below the top of the top of the tank leaving an air space. It takes too much time to "fill up" because of "blow back". When it starts that, I just quit and hit the road. After several fill ups over a few thousand miles, the average mpg begins to emerge and level out. At that point it really doesn't make much difference whether your tank is filled "completely" or not.

Jim E

sailorm0n · 12-06-2011, 07:18 AM

Is there a chip for a Cat 330HP to help with fuel economy?

1ciderdog · 12-06-2011, 10:15 AM

You might look at the MP-8. TS Performance MP 8 Fuel Economy Module
Safe Travels
Bob

trouble&rose · 12-06-2011, 10:40 AM

Hello,

We have a 2007 Endeaver HR coach 33,000 Toad 4000
Cummins ISL 400
62 MPH is our sweet spot....we set the cruise and get 10 MPG

Love the 400 ISL

Warmest regards Trouble

Mr_D · 12-06-2011, 06:49 PM

Quote:

Originally Posted by sailorm0n

I am selling my Viking Motor Yacht and am contemplating the purchase of a used motorhome, class A diesel pusher. I am looking at a variety of brands, possibly a Monaco with a Cummins or Caterpillar, length of 37-45 feet. Can anyone tell me about what the fuel mileage I could expect?

You can expect what ever you want, but figure on 6-8mpg depending on how you drive.

Mr_D · 12-06-2011, 06:51 PM

Quote:

Originally Posted by sparkydog

We did the boating thing as well, but love our MH. 45' HR Imperial with 425 ISL Cummins, 7.6 mpg towing.

Us too, but sold the boat and boat well, then quit the yacht club. Enjoy the MH much more although my wife would like a small boat to do some fishing from.

Mr_D · 12-06-2011, 06:56 PM

Quote:

Originally Posted by rough road

apairajays, the only way to know for certain what mileage you are getting is to fill to a visible level in the neck, drive and then refill to that level. Checking mgp this way is 100% accurate whether one drives 100 miles or 100,000 miles; the only variable would be over the mechanical lifetime of the engine as fuel consumption might be affected by a break in period and this I think would only be applicable to larger engines.

So if I drive 100 miles on a flat road I'll get the same mileage as going up or down a 6% grade?
I don't think so!!!
On the flats I show 14-16mpg, on a 6% upgrade I might show 3mpg and on the downgrade I'll show 256mpg on my VMSpc.

rough road · 12-07-2011, 05:15 AM

Mr. D, I can assure you that if you fill your tank to a level in which you can see the fuel, drive anywhere you wish over any type of terrain/grade you wish and refill to the same level in the neck it did indeed take you whatever amount of fuel you put back in to travel the distance and roads you traveled-this you can take to the bank.

No you will NOT get the same mileage on a flat road as going up grade and I never inplied any such thing, but you will get the same mileage going up the same grade every time; all things being equal of course.

You in all probability won't like the numbers you see but as in many instances, the truth is unpleasant.

Please don't read anything into this, I really do like you class A folks and I really do like looking at what some can spend their money on, but knowing what I know about punching huge holes in the atmosphere with very large and very blunt vehicles 99.99% of all Class A mpg reports are 100% Class A tall tales; by people who really really want to believe the skewed numbers they come up with.

What we see while traveling is this, nearly all Class A drivers are operating significantly over the speed limit-and thats fine by me- and all Class A drivers seem to be hell bent on proving that their magnificent motor homes can also maintain those speeds up any grade,( ESPECIALLY when someone lower on the rv foodchain is ahead of them-admit it guys you KNOW I am right) under these circumstances I know it impossible to acheive any mpg number over the mid to lower:upper single digits in the class vehicle under discussion.

Add in the 'toad' (two come to mind, one lucky guy or gal was pulling an H1 Hummer another was pulling a Land Rover Defender) or typical Class A 'trailer' and I don't see any number over 6mpg possible, even down the longest grade on the planet.

Rfw1955 · 12-07-2011, 08:37 AM

Rough road you are so right

pumper9x9 · 12-07-2011, 11:11 AM

2002 coach with a 400 hsp ISL if we are just driving we get 7-9 mpg however we full time and I figure 5-5.5gpm with generator, heating, and driving. If I get better great. But I always plan and budget for lower milage than I'm expecting. I always just fill up to the first place it clicks off at the pump because I have found that I can overfill the tank pretty easily after that point and it just spills on the ground. Also watch for the small diameter fill hoses with slow fill speeds they may not click off at all and then you've paid for a gallon or two that spilled out before you saw it.

RVNeophytes2 · 12-07-2011, 12:14 PM

Quote:

Originally Posted by sailorm0n

Can anyone tell me about what the fuel mileage I could expect?

I'm driving my first RV, bought a year ago from friends. My buddy says that he carefully tracked mileage during their memorable 15,000 mile tour of US landmarks to celebrate earning their citizenship, he got 7.2 mpg.

DW and I just rolled in from a tour of East Texas over the weekend, pulling a 5,000 lb toad; I showed 7.3 mpg. Lots of stop and go driving, pushing it to mix well with heavy traffic. No doubt we could hit 8 mpg if we worked on it.

The C7 has run flawlessly for 93,000 miles, the only problem was due to fuel contamination, on his watch.

WanderingKat · 12-07-2011, 01:07 PM

As a newbie still in search of my first MH, I was wondering if a FRED vs DP made any difference. I've read in a few forums that the Thor Serrano makes between 13 and 15 mpg in the real world as claimed by the manufacturer.

I like the Serrano a lot but haven't committed to it because I'd like to see a few Monacos and Newmars. I do like the quality I've seen in Tiffins.

(In the DC area, MH dealers are few so it takes a while.) I worry a bit about mileage because, while I can afford it now, I may not when I retire--assuming I ever do.