luckydog1949

Diesel Motorhome MPG-- Honest Answers Please

211 posts in this topic

The most reliable source is WW Williams, I also have a dead bus yard, I will PM you with that phone number. Quite a number of parts are also available on ebay, this engine was many produced and used for fire trucks and marine use.  Also if BillA is still looking, the WW Williams in B"ham., Al still has a two stroke mechanic that has help me out with some tough questions, just call them and ask for the two stroke mechanic.

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that vintage birds website is just about dead. I'd check with the Prevost Community, which I'm a member of and is quite active- and they know Prevosts

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The engine was replaced but the problem remains.

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Most of the folks on the Prevost Community are....never mind......I have not had any luck trying to have a discussion with the folks on that forum.

The POG's (Prevost Owners Group) is even worse!  There is another Prevost owners group frequented only by multi-millionaires looking to save 10% on their camping fees.  I am so far removed from the reality of most Prevost owners that I am officially the red headed step child!

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Even though I don't have a DP, I read this group of posts with interest.  As I read about the MPG numbers, one thing seemed to stand out.  The high speeds at which the coaches were being run.  I know there were the comments that if you can afford a DP, you don't need to look at the fuel expenses.  That may be so for some of you, but some out there can afford the DP because they DO look at fuel costs.  Kind of the attitude that Bill directly above noted in the Prevost owner groups.

My experience with diesels is with 'pullers' not 'pushers'.  We ran 450hp Volvo engines, pulling 60-89,000 (and sometimes 100,000) pounds all around Oregon, Washington and portions of Idaho and Montana.  That also was with 18/26 tires (5-7 axles) on the ground (causing a lot more road resistance than the usual 2-3 axles).  This was connected to a Volvo iShift transmission.  We would average 8.8 miles per gallon based on 3.6 million miles driven per year.  The key to this is that we ran the truck speed limit in what ever state we were driving in.  Thus, 55 in Oregon, 60 in Washington and 65 in Idaho and Montana.  We also ran some in California where the truck speed limit is 55.  Also, the speed limit for ANY VEHICLE TOWING ANYTHING, and of course that includes Motor Homes with a toad, is 55mph.

Even though my Motor Home is only a gasser, it is 57 feet long including my toad, and it drives MUCH more like a truck than my Subaru does.  So I drive it similarly.  Just my two cents worth.

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We have 5 gears and the newer coaches have 6 gears.  How many gears did you tractor/trailer have?  Also, running between LA and Las Vegas I must maintain 55 MPH since I am towing.  This makes almost no difference in the end result of my miles per gallon.  I would guess that moving from 55 to 70 would reduce mileage by .1-.2 MPG per 10 MPH.  I have never gotten better than 5.5-6.0 no matter where or how I drive the coach.

Just my actual results and that may or may not be worth 2 cents.

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Thanks for the reply Bill.  The iShift had 10 gears.  I am sure I didn't mention that it was an automatic transmission.  The company I worked for went to those a few years ago.

I had always been told that your mileage decreased by 10% for every 10 miles per hour you increased your speed over about 50-55 mph.  Here is a quote I found on a website after reading your post:

"Increasing your highway cruising speed from 55mph (90km/h) to 75mph (120km/h) can raise fuel consumption as much as 20%. You can improve your gas mileage 10 - 15% by driving at 55mph rather than 65mph (104km/h)."

So, if one is getting 6mph, a 10% decrease would be .6 mpg or down to 5.4 mpg. 

My comment about California and speed limits were in response to another poster who said he ran 65 from "Oregon to Arizona and back to Washington, including Tehachaipi and the Grapevine" which means he traveled in California.  Not pointed to you at all.  The reference was just that not all DP owners are the same:  rich and don't have to worry about fuel costs.

Wayne

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Speaking of speeds, I've seen big rigs doing 80 plus down the interstate -- given tires are probably on rated for 75 mph and the sheer force required to stop these rigs --- I just shake my head and wish them the best as they pass by me.

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I'm late to this discussion however my advice is that you should not be overly concerned with fuel mileage. If you have a diesel pusher just enjoy the adventure. Make sure you do regular maintenance including all filters and add some injector cleaner every few tanks of fuel. I just finished a 10,000+ mile trip to Alaska, got about 8mpg. But more importantly, the 55 day adventure cost me less than $150 per day, everything included (fuel, food, entertainment, activities). I never worried where I was going to sleep, eat or go to the bathroom. We stopped whenever we found a lake, river, mountain view or valley that we liked. Try doing that in a car that gets 30+ mpg.  Enjoy the adventure, you are driving your personal one bedroom luxury apartment. 

If you don't believe me, figure out what you would pay for gas, lodging, meals and entertainment driving a car on a 55 day, 10,000 mile trip. Joe

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11 hours ago, Donajoe said:

I'm late to this discussion however my advice is that you should not be overly concerned with fuel mileage. If you have a diesel pusher just enjoy the adventure. Make sure you do regular maintenance including all filters and add some injector cleaner every few tanks of fuel. I just finished a 10,000+ mile trip to Alaska, got about 8mpg. But more importantly, the 55 day adventure cost me less than $150 per day, everything included (fuel, food, entertainment, activities). I never worried where I was going to sleep, eat or go to the bathroom. We stopped whenever we found a lake, river, mountain view or valley that we liked. Try doing that in a car that gets 30+ mpg.  Enjoy the adventure, you are driving your personal one bedroom luxury apartment. 

If you don't believe me, figure out what you would pay for gas, lodging, meals and entertainment driving a car on a 55 day, 10,000 mile trip. Joe

Welcome to the forum. You aren't late just the latest.:lol:

Bill

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Bill, well said !

joe.  Welcome to the Forum! :)

I get 6.2-6.8 at 63-65 mph, 1650-1700 rpm on a 425 Cummins, 3000 Allison, 45 foot DP, 54,000+/- pounds! :P

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