Stickler
Central Oklahoma
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Joined: 09/20/2003
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I talked to an engineer at Monaco this last week and he was telling me they are doing a lot of work with Diesel rigs trying to figure out how to improve mileage. Obviously, they are working on ways to counteract the high fuel prices. He told me that they have been working with Cummins ISL 400HP rigs and they have found that there is as much as 30% difference in mileage between driving at 55 MPH and 65 MPH. I think we've all suspected there was considerable difference but I never thought it would be this much. I'm a 65 MPH guy with my Endeavor and I'm getting ready to go on about a 4000 mile trip and will do it at 55 MPH to see if this is anywhere near true. I'll let you know what happens.
Has anyone tried this already???
Roger
2007 40PRQ Quad Slide
HR Endeavor
2006 Acura MDX Toad (4 Down)
Central Oklahoma
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marvmarcy
Polson, MT, USA
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Joined: 04/19/2003
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It would be interesting to see what happened with an ISM or ISX at those speeds. I'm guessing the mileage difference would be less as the engine size increased.
JMHO
2001 Volvo VNL42T420, ISX450/1650, super 10sp w/GearMaster
2003 Newmar Mountain Aire 38RLRK
Piaggio MP3 400 scooter
RVing since 1979 - Fulltime since 2000 (mostly CO, MT, NC & Key West)
Retired USAF
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wallynm
Los Alamos NM
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Joined: 09/27/2000
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Last trip out we ran 55 to 58 for over 500 miles and got 9.3 MPG vs 8.3 average MPG for the previous 70,000 miles @ 62 to 65.. One short trip has not convinced me this will hold for the long haul but we shall see.
Stickler wrote: He told me that they have been working with Cummins ISL 400HP rigs and they have found that there is as much as 30% difference in mileage between driving at 55 MPH and 65 MPH
Has anyone tried this already???
Have a Cat Engine Yahoo Group or Cat RV Club Web Page
Have a Freightliner Yahoo Group or FCOC Web Page
wallynm@yahoo.com
2002 DSDP 3567 PUSHED BY KITTY KAT
THOSE THAT DO NOT KNOW HISTORY ARE DOOMED TO REPEAT IT
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thunderstruckhd
Ft.lauderdale,Florida
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My time is worth more then a few bucks for fuel...
2006 Allegro Bus, 42QDP, Tag axle, 400ISL.
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retired logger
WA USA
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Joined: 12/10/2003
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thunderstruckhd wrote:My time is worth more then a few bucks for fuel...
Well some folks here are not as flush as you indicated you were...Any saving a person can come up with is a big plus for the person and the environment I might add..
Short time young and a long time old !
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Gale Hawkins
Murray, KY
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Joined: 07/22/2007
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We have run a lot of our first 4K miles at 70 MPH just to push the 1992 454 engine and drive train since there were no mountains involved for a real test since it had 91K miles on the engine and after some tuning up and especially replacing the fuel filter it pulls well and does not use oil so there is no real reason to push it just of prove it is a solid rig.
We have a 600+ mile trip planned in a couple weeks and since it is hilling from here to Cincinnati I am thinking of setting it on 55 MPH and running in D instead of OD and see what kind of MPG we get. This is not a rushed trip with any deadline for any stop.
Saving some gas would be a plus if that is the case but in the event of a blow out or crash I expect running 15 MPH slower could really increase our odds of surviving the accident.
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wny_pat
Western NYS
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Joined: 08/11/2007
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Stickler wrote:I talked to an engineer at Monaco this last week and he was telling me they are doing a lot of work with Diesel rigs trying to figure out how to improve mileage. Did he tell you what transmission and what rear end ratio? That is as much a factor as the horsepower/torque of the engine. Also the tire size and the weight of the rig. Also the suspension. If they are just working on the diesel engine, they are barking up the wrong tree. It's all tied together!
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skipnchar
Topeka Kansas USA
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Joined: 12/17/2003
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Not exactly earth shattering news about slowing down. Remember the 55 MPH speed limits back during the oil embargo? That's what it was all about THEN too.
2004 F-150 HD 3,050 lb. payload
Rockwood 8314SS 34' travel trailer
We have enough YOUTH...how about a fountain of SMART
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Beavis
NW IN
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Joined: 12/22/2002
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My expierence tells me your plan will fail.
I tried 55 mph but checking the tach told me that I was in 5th gear,
mileage sucks in fifth gear. Check it out.
American Dream
New Road King- Just for fun
FMCA 288578
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snookmjt
On the road
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Joined: 05/23/2006
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We just drove a bit over 2700 miles from Florida to California. Our MH has the Cummins 400 HP engine. We kept the cruise control set about 60 mph for the most part. The computer says our average mpg is 7.1, the instant mpg on level ground was between 8 and 10 mpg.
More interesting is the fact that all the way across country on interstate highways traffic of all kinds passed us like we were standing still. Evidently the price of fuel has not gotten to the point where people are willing to slow down and save money.
My two cents worth.
Tim and Mary Jane
Mandalay 40B
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