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Midwestern4x4.com
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Discussion Starter #1
all numbers are highway driving at 65mph
My 02 f250 ccsb auto 4x4 will get 20-21.5 unloaded and towing my offroad truck will get 10.5-11.5

this seems like quite a drop since my early99 f250 sclb auto 4x2 would get 19-20 unloaded and 13.5-14.5 towing the same setup

both trucks have same mods: (afe intake, 4in tb exhaust, dp tuner) except for the 02 has a regulated return and the "wicked wheel"

is there something wrong i should be looking for that the 02 drops so drasticly with a load?
 

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It does sound like too much of a differential. I get about 21 mpg at 70 mph not towing, and 14+ towing a 6000 pound travel trailer at 60 mph. I have a 96 with an E4OD and 3.55 gears. My mileage differential is closer to your 99 than the 02.

What about your CPS? I've read that some are better than others in regards to mileage...just a wild shot here. I'm still on my original one.
 

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I have a similar drop, from 20 to 11 when towing the travel trailer.
 

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Midwestern4x4.com
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Discussion Starter #5
gearing maybe?
both trucks have 3.73 gears

It does sound like too much of a differential. I get about 21 mpg at 70 mph not towing, and 14+ towing a 6000 pound travel trailer at 60 mph. I have a 96 with an E4OD and 3.55 gears. My mileage differential is closer to your 99 than the 02.

What about your CPS? I've read that some are better than others in regards to mileage...just a wild shot here. I'm still on my original one.
In the 99 I've had the black and grey ones and I noticed no difference in fuel economy, I'm not sure which one the 02 has.
 

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International Coal Roller
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383 Posts
CC 4x4 are heavier, might be injectors too Ive heard of people getting better milage tuned with the older single shots vs the split shots in the 02-03's
 

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Midwestern4x4.com
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Discussion Starter #8
both have split shots. the e99 had AB injectors and a 15* hpop the 02 has AD injectors and a 17* hpop.

I havent confirmed this yet but my theory now is that the hpop is not supplying enough pressure in the 02 for the extra load when towing

i have a set of 160cc/30% single shots coming for the 02 that will require less oil to operate than the split shots. I will have to do some data logging while towing and see if this fixes the problem or if i need to upgrade the hpop
 

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Ive got a 2001 F350 2WD crew cab with the 7.3L. I have the 4" MBRP exhaust turbo back and the edge programmer. I was pulling my 27' gooseneck with my tractor and 6 seater mule on it and couldn't get the truck over 50 mph on flat ground....... Any suggestions?
 

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International Coal Roller
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383 Posts
open up the intake a little and then throw away the edge, all its gonna do is jack up the icp, then start checking all your vitals, is there oil in the icp sensor, hpop duty cycle, boost leaks, up pipe leaks, etc.
 

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Dude, you gotta consider the road load equation.

It has terms in it accounting for weight and grade.

Generally Road load (in pounds) = (grade x weight)

Also rolling/bearing resistance is 5% of weight


Assume a 2% grade. Your truck weighs about 7,000 lb. Your trailer (empty weighs 1500lb) and you are hauling a 4,000 payload for a GCVW of 12,500 lb


Case 1. Running empty

Weight/grade load = (7,000 lb x 2%) = 140 lb
Rolling resistance = (7,000 lb x 5%) = 350 lb
Total load = (140+350 lb) = 490 lb

65 MPH = 95 ft/sec

Power required to maintain 65 MPH = (490 lb x 95 ft/sec divided by 550 ft-lb/sec-HP) = 84.6 HP



Case 2. Towing

Weight/grade load = (12,500 lb x 2%) = 250lb lb
Rolling resistance = (12,500 lb x 5%) = 625 lb
Total load = (250+625 lb) = 875 lb

65 MPH = 95 ft/sec

Power required to maintain 65 MPH = (875 lb x 95 ft/sec divided by 550 ft-lb/sec-HP) = 151,1 HP


You can see that while towing you need (151.1/84.6) = 79% more hp

Add on an overarching aero load of 104 HP

And you see the energy needed towing is 35% greater while towing

My calculation obviously underestimates your trailer & payload weight and its aero drag.

I don't think MPG being cut in half for towing is all that out of line.
 

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I know my Excursion with a 44 gallon tank can go 800 miles on a tank empty and 400 miles towing our camper. Seems legit to me.
 

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We tow 95% of the time and with a 6500 lb. flatbed gooseneck empty we still get 15 mpg at 65mph. But aero drag on certain loads can knock us down to 10mpg. Empty no towing we see 22mpg at or around 65mph. Weight of load is not as important as aero drag of load. PHP hydra chip and water/meth helped almost 20%.:psn:
 
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