Community Forums

pivotdoc · 12-31-2013, 05:54 PM

These posts are all spot on, my experience is the MPG is directly related to the speed you drive. That said, I usually run 70 to 75 and get 6 - 6.5..........I know it would be better if I slowed down!..........

JB

Steve Ownby · 12-31-2013, 05:57 PM

Quote:

Originally Posted by 1jrbrooks00

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

My ISM was manufactured in late '02 and is pre-EPA devices. The ISM also was fairly lightweight for its power and the later engines with the EPA gear are not as economical. The averages I have seen for the ISX, which has been available from 525 to 650 is more on the order of 5.5 to 7 mpg. The DD60 that has been available in some coaches over the years is pretty similar. The GVWR of the motorhome and the savvy of the driver have a lot to do with Milage.

You will get more meaningful comparisons if you identify the engine by make and model rather than HP output. You will fine that there are engines with the same advertised HP that are substantially different. This is most common in the mid range engines.

Crasher · 12-31-2013, 06:03 PM

A few years ago two coaches stopped overnight. It was a father and son team. The son had a tag coach with 400 hp and the father had a Newel with 600 hp. When asked, the son said he got 7 and the father got just under 5 traveling the same roads at the same speeds. I didn't ask what speeds, but figured that with what the Newel cost, the father didn't care what it got.

thrushl · 12-31-2013, 06:21 PM

Quote:

Originally Posted by pivotdoc

These posts are all spot on, my experience is the MPG is directly related to the speed you drive. That said, I usually run 70 to 75 and get 6 - 6.5..........I know it would be better if I slowed down!..........

JB

70-75? You speed demon you!!!

hogdriver · 12-31-2013, 06:32 PM

I get 6-7 in a 43 Ft running a 450 ISL pulling a 4500 lb Jeep. I had a 35 ft 1995 Holiday Rambler with the 5.8 Lt 230 HP Cummins that was not real zippy, but it always got 9-10 mpg. Sometimes smaller diesels working closer to their peak produce better mileage.

dykedelta1 · 12-31-2013, 07:14 PM

Quote:

Originally Posted by 1jrbrooks00

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

I get 11.6 wiyh 5 9 cummons in 37 ' HR ENDEAVER.

chiefneon · 12-31-2013, 07:36 PM

Howdy!

I was told once by a salesman at a RV show that "if you can afford to buy one you don't have to worry about the mileage or the price of feul"!

"Happy Trails"
Chiefneon

brandonklink · 01-01-2014, 06:49 AM

I have a cummins 500 ISM. I also live in WV so no matter which direction I go I am pulling mountains. I to a tow a 3/4 Tom GMC 2500 Denali Diesel my total weight is over 50K. I have a heavy foot usually running 70-75 mph. In the mountains I usually just stand on it and and my average is about 3.5 on flat I usually average 6-7. As someone else said don't worry about the fuel it's about the journey! LOL. Good luck in your purchase.

CC Rider · 01-01-2014, 08:33 AM

Selah,
I will buy used. I am gathering info to help determine what is best for my needs. I do not want to strain going up hills and mountains, but I do not want a very low mpg in order to achieve that either. So, I will compromise on engine power needed and mpg needed. Still gathering info to make a decision. Hope this helps.

CC Rider · 01-01-2014, 08:44 AM

Johnny Rottten,

All good points. thank you. R U saying that diesel engines 2008 and older get better mpg than 2009 and newer because of federal emission regulations? Would you say a 600hp would get worse mpg that a 500hp going same speed in same conditions?

Steve Ownby · 01-01-2014, 08:52 AM

Quote:

Originally Posted by 1jrbrooks00

Selah, I will buy used. I am gathering info to help determine what is best for my needs. I do not want to strain going up hills and mountains, but I do not want a very low mpg in order to achieve that either. So, I will compromise on engine power needed and mpg needed. Still gathering info to make a decision. Hope this helps.

Since you are looking used you will have more engine variables than current new production. The Cummins ISX in 12 liter and 15 liter form make up most of new coach power in 45' size. Next is the ubiquitous ISL in 450 hp form.

If you go back to pre '10 coaches you will find Cummins, Cat and Detroit Diesel power. Look for a coach with less than 100 pounds of vehicle weight per HP. You will not find any 45' coach weighing over 40k that will give substantially greater Milage than another. Speed and topography are the big issues. Do your homework, buy the highest quality coach you can and learn how to drive it. Invest in a Silverleaf product and learn the characteristics of your power train. Knowledge is power.

CC Rider · 01-01-2014, 08:53 AM

Thrushl,

I feel it inconsiderate to have this huge vehicle on the road with cars and commercial rigs that backup the traffic or make it dangerous for them to pass. If a vehicle cannot maintain reasonable speed then pull off and let them pass or get a vehicle that does the job. So many slow rv drivers are inconsiderate to this and cause others to think poorly of rvs in general.

CC Rider · 01-01-2014, 08:56 AM

pivotdoc,

what is your setup and weight please?

CC Rider · 01-01-2014, 09:01 AM

What is ISM ISX DD60?

Quote:

Originally Posted by Steve Ownby

My ISM was manufactured in late '02 and is pre-EPA devices. The ISM also was fairly lightweight for its power and the later engines with the EPA gear are not as economical. The averages I have seen for the ISX, which has been available from 525 to 650 is more on the order of 5.5 to 7 mpg. The DD60 that has been available in some coaches over the years is pretty similar. The GVWR of the motorhome and the savvy of the driver have a lot to do with Milage.

You will get more meaningful comparisons if you identify the engine by make and model rather than HP output. You will fine that there are engines with the same advertised HP that are substantially different. This is most common in the mid range engines.