12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

Performance Versus Mileage

Old Sep 1, 2011 | 11:44 PM
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Default Performance Versus Mileage

I'm on my second Dodge truck. My first was a 95 2wd getting about 22mpg empty 17mpg pulling a 30' car hauler. It was a standard cab and we couldn't take the family when camping so I sold it and bought an 89 Chevy CrewCab SixPack Dually with a 94 12v transplant. The truck has a 700r4 with a Gear Vendor OD on it.

Empty I'm lucky to get 15-16 and pulling my 5th wheel and keeping it at 65 I am getting around 13mpg. This is certainly no where near what I was hoping. I realize this truck is heavier, it's a dually etc but any thoughts on whether this is about typical?

Now the guy I bought it from said he was pulling a 20k race setup and plenty of power. My 5th wheel is about 8k loaded it's rather small and pulling the hills with my foot in it, I'm pulling 20-25lbs of boost and barely maintaining. So I want mileage but also a bit more power. I don't think there is any mods to the injectors other than he replaced them with Bosch injectors. The exhaust looks to be about 3" at best so I suspect some restriction there. Reading other posts trying to see if I can gain both at the same time. I haven't done much with mods on a diesel but ready to start trying to figure out all of this.

Any suggestions? Thanks
 
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Old Sep 6, 2011 | 10:58 PM
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that heayt of a truck thats wht happens
 
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Old Sep 6, 2011 | 11:43 PM
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What????????
 
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Old Sep 6, 2011 | 11:55 PM
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whats the gear ratio and how big are the tires?
 
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Old Sep 22, 2011 | 10:57 PM
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lots of stuff you can do to a p-pump, advance timing to 16.5 to be safe, adjust or upgrade the fuel plate, and remember when ya go upping the engine for power and performance, YOU WILL find and have to up grade all the weak links,,, been there done that,, good luck
 
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Old Oct 8, 2011 | 02:30 AM
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I recently went to our local Diesel Performance Shop and talked to him about my absolute "CRAP" mileage and what seems like an underpowered vehicle. I found out a couple of things from talking to the owner. 1st he knows the truck well and has the same setup other than his is a stick he's getting about 21mpg. So he mentioned that I need to check the gearing (already suggested) and he has an upgrade package (not sure what all) but he bumped his power from 129hp at the rw to 256at the rw after the changes. He's very reputable and knows his stuff however $1400.00 is a bit of change. I definitely want to do it but will havce to ask him what all is done. I did find out that my motor is a G1 motor most likely 93. So still hoping for some improvement.
 
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