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Old 09-23-2015, 09:32 PM   #1
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RPMs/MPH - Maximizing Fuel Economy

I'm curious if there is a "sweet spot" that yields maximum fuel economy relative to engine RPMs and coach speed (MPH). I have a 2016 Dutch Star 4018 which has the Cummins 450 HP engine. I called Cummins today to get their input and was advised this engine reaches maximum torque between 1400-1500 RPMs and maximum HP between 1800 to 2100 RPMs. But because he did not have the transmission specs he was unable to determine the most efficient RPM/MPH combination that yields the best fuel economy. I assume how the coach is loaded in terms of weight has an affect but I'm interested in hearing from others who have learned or have determined the best RPM and/or MPH combination that yielded the best fuel economy for their respective coach. Would appreciate hearing from others that are a lot smarter than me in knowing how these wonderful machines run and at what RPM/MPH combination I should be shooting for. I truly enjoy the ride and the view through that huge windshield and I'm in no hurry to get down the road, just would like to be traveling economically.



Allen & Angel
2019 Dutch Star 4369, 2016 Dutch Star 4018 (Sold)
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Old 09-23-2015, 09:37 PM   #2
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Usually it is 200 rpm over peak torque rpm. On our 2002 DSDP ISC with Banks kit that was way higher than I wanted to travel as the Banks kit let the engine have 1200 ft lbs from 1400 to 1700 rpm. 1650 was about 62 mph so that's what I drove at where legal.
With the Magna 60mph is 1350 and max torque is 1950 lbs ft from 1100 to 1600 rpm so no way am I going to run 1800 rpm!

2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
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Old 09-24-2015, 02:49 PM   #3
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Camp Freightliner recommended to run about 1650 rpm and that would be about 62-63 mph for peak mpg.
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