6.7 Best RPM - Dodge Cummins Diesel Forum
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post #1 of 6 (permalink) Old 01-13-2008, 02:36 PM Thread Starter
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6.7 Best RPM

What is the RPM range for the best fuel mileage?

With the auto 6 speed trans, is it a good idea to drive in 3rd or 4th gear to keep the RPMs up, especially on cold start driving?


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post #2 of 6 (permalink) Old 01-16-2008, 05:24 PM
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typically for driving freeway speeds (65) running just under 2000 RPMs is the best. Though with a few of the mods i have done it now seems running at 75 (2200 RPMs) i seem to get a little better mileage. This is of course with the manual transmission.

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post #3 of 6 (permalink) Old 01-16-2008, 07:57 PM
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18 is my best so far with my 08 empty but that is also running at 75 plus with 410 gears

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post #4 of 6 (permalink) Old 01-16-2008, 11:35 PM
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Keep it under 2K on the highway to get the best mileage. Anything over and it starts drinking fuel

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post #5 of 6 (permalink) Old 01-16-2008, 11:59 PM
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I've tried running 60mph in different gears on my 6spd auto and the best my truck will do is 11-13mpg and thats calculated by hand not from the overhead . How are someguys getting 18mpg ?
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post #6 of 6 (permalink) Old 01-17-2008, 10:32 PM Thread Starter
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What About Local Driving

Thanks guys for the input.

How about local driving in town?

Should you use the gears in the 08 6 speed auto trans to keep the rpm's up at 25 and 35 mph?

I am running 1800 rpm at 25 mph in third gear.

What does that do to milage and the auto trans?


Dave Jones
08 Ram 2500 6.7L EB 6 Speed Auto Trans
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