Community Forums

CC Rider · 12-31-2013, 12:27 PM

Can you tell me what I should expect the get in MPG for a 45ft MH fully loaded with 5,000 lb toad? I am looking at four different engines; 500hp, 525hp, 600hp, 650hp. What should I expect in rocky mountain terrain? What should I expect in flat terrain? What should I expect in hilly terrain? I will be in hilly to flat terrain most of time with occasional rocky mountains. If anyone could help me with my decision on engine and mpg I would greatly appreciate it. Thank you.

pivotdoc · 12-31-2013, 12:33 PM

I would think 500 hp would be plenty w/ that toad. I pull a 32' race trailer weighing 9700# loaded with a 400 Cummins and it has no problem topping Raton pass @ 48 mph. Getting 6 to 6.5 mpg, that's all I can expect...............

JB

CC Rider · 12-31-2013, 12:39 PM

JB,
thanks. do u average 6-6.5mpg? Is this mainly in flat terrain?

mmartin · 12-31-2013, 12:54 PM

The old saying is: better to have and not have to use it vs. not having it and needing it. The smaller engines will get better mpg on flat driving but will be cancelled out when you need to keep your foot in it to get up and over those hills. The manufacturers offer the larger engines to the larger coaches (42'-45') for a reason. You have a lot more capacity to fill and I am sure you have upgraded interior which also adds to the weight. Depending how much you are going to drive and how long you are going to keep the coach, checking the price difference between engines would definitely be a priority. Engine maintenance cost will be generally the same

Steve Ownby · 12-31-2013, 01:05 PM

Quote:

Originally Posted by 1jrbrooks00

Can you tell me what I should expect the get in MPG for a 45ft MH fully loaded with 5,000 lb toad? I am looking at four different engines; 500hp, 525hp, 600hp, 650hp. What should I expect in rocky mountain terrain? What should I expect in flat terrain? What should I expect in hilly terrain? I will be in hilly to flat terrain most of time with occasional rocky mountains. If anyone could help me with my decision on engine and mpg I would greatly appreciate it. Thank you.

Realistically you are looking at a range of 5.5 to 7.5 depending on your driving style and conditions. The biggest factors are vehicle weight and speed. My 500 hp is capable of 8 + when driven conservatively and the Conditions are flat to rolling. My coach weighs 45k with toad.

CC Rider · 12-31-2013, 01:14 PM

Steve,
thanks. so if you had a 525 or 600 hp you would not get the 8 as you do with the 500hp?

HHIDan · 12-31-2013, 01:23 PM

From everything I read and from my own experience you will get between 5.5 and 7.5 as stated in previous post. The speed you drive will have more impact than 400 vs 600. And IMHO coach manufacturers offer a 600HP engine for guys with a bigger wallet and not because it's absolutely required...

leatherneck · 12-31-2013, 01:57 PM

weight of the motor home and larger engines will need more fuel. I use to drive and tractor and trailer with 60 to 75 thousand lbs. A 400 hp will do good in the hills just let let the engine do it job stop trying to fly up the mountains cause you will fly faster going down. Bigger engine take more fuel to operate. Take a pick more fuel nph or going fast.

nforus · 12-31-2013, 03:23 PM

We average 5.6 over all terrain, 600 hp ISX, coach weighs 50,250 loaded with water, gear, fuel, and occupants. I think the TOAD adds another around 4500#'s. We run between 65 and 72 MPH.

Selah · 12-31-2013, 04:30 PM

Just out of curiosity, are you going to pick which $400K+ coach based on MPG
Or is there a manufacturer that offers the same coach with optional engine size?

jeryan59 · 12-31-2013, 04:36 PM

i average between 5.5 and 6.0 mpg, 2009 425 hp Cummins grossing about 58,000 lbs with trailer. I usually set cruise on about 64 mph.

I think year of motor will affect your mileage as well, newer motors have more emissions which I see as negatively affecting mpg.

My 1999 350 hp Cummins without tag axle I would average 7.0-7.5 mpg with same trailer and load. Yes the 2009 set up is heavier, but most of the additional loss in mpg is attributed to emissions in my opinion.

One thing I would look at while you are calculating, is approximately how many miles you will drive annually? If you are average RV, about 7,500 miles per year, at 5.5 mpg you will use about 1,364 gallons per year. If you average 6.75 mpg, you would use 1,111 gallons, so at $4.00 per gallon for diesel, that is about $1,000 difference per year in fuel costs, which in my opinion is very small amount of money considering the fun, size of your motorhome, and power you will have with any of your options.

If you averaged heavy use at 12,000 miles per year, 405 gallons more at 5.5 mpg versus 6.75 or $1,620 annually. From my experience these are not the most significant dollars in RVing in a Class A diesel which I have done part time over the past 13 years. I'm not minimizing your concerns on the mileage (assuming that is your concern?); just pointing out the real costs differences in my opinion aren't that significant to the overall costs associated with these options.

But generally speaking, as you increase HP your mileage will go down assuming we are looking at engines newer than 2008. Depending on the manufacturer of the engines, mine have both been Cummins, the Cummins website will give you an estimate on mpg for each motor.

Good luck in whatever you decide, I don't think you will make a bad decision one way or the other from your options you are inquiring about.

Arch Hoagland · 12-31-2013, 04:42 PM

Quote:

Originally Posted by Selah

Just out of curiosity, are you going to pick which $400K+ coach based on MPG
Or is there a manufacturer that offers the same coach with optional engine size?

I was wondering the exact same thing.

Triker56 · 12-31-2013, 05:07 PM

I am wondering why anyone that has the money to buy a MH with that much HP.
Even cares what the MPG will be.

Maybe the OP can just plan on 5.5 MPG and then be happy if it gets more.
The real cost will be all that depreciation that will happen after buying it.

thrushl · 12-31-2013, 05:17 PM

Friends, let's not forget that a HUGE part of MPG in these engines is as some pointed out --- THE DRIVER.

My two cents, I have a 515 Detroit and I run the hills on both coasts faster than I should and the engine doesn't break a sweat. I'm at 56K with trailer. I normally get in the 7.5 range OVERALL.

My comment; all these engines will do great. Don't pay extra for a larger engine. Pick the coach you want and enjoy it.