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Old 09-01-2011, 07:29 PM   #27 (permalink)
rmay635703
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Join Date: Jun 2008
Location: Somewhere in WI
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Quote:
Originally Posted by DieselFan View Post
Hi Big Dave

Your experience with the Gearvendor overdrive unit has me considering one for my Ram 3500 4x4, 6sp, 3.73 rear end. However, highway rpm would fall to around 1500 from 1925 with the current stock setup.
Isn't that a bit off peak fuel efficiency for the 5.9 L Cummins, I read that they are most efficient at 1950 rpm but then I don't want to end up driving at 80 mph as wind resistance would kill the potential fuel efficiency gains.
Just because your engine can make power the most efficiently at X does not mean you will get the best FE steady state generating 400hp.

You need to look where your motor most efficiently generates the amount of HP you need to move and that may well be near wot at low RPMs.

Unless of coarse you P&G.

Quote:
Originally Posted by DieselFan View Post
What's wrong in my thinking?
Ivan
Driver variability, an overgeared vehicle allows a talented individual to get far more FE or someone with no clue to get less.
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