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Discussion Starter #1
Are all those people claiming 20 plus lying?
......

I just finished my cummins conversion into a 78 F350 and curious to what people are REALY getting mileage wise...
 

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Friends truck,1996 std cab 4x4. #10 plate, marine injectors, 4" exhaust, nv4500, 3.55 (? bit fuzzy, can't remember for sure). 265 tires. Put v10 front springs and cut the factory rear block in half to lower the truck a bit. Owner smashed his ankle and knee and climbing in and out was a pain so we lowered it. He gets 18-21 depending on winter vs summer fuel. 23-26 hwy. I know because I have borrowed this truck many times and had to fill it up many times. He wants to fuck with the timing, but can't find anyone local to do it. Supposedly he is leaving a few MPG with the stock timing.

My 24 valve couldn't touch it on power or MPG.
 

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'82 Scrambler, '14 Rzr
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Are all those people claiming 20 plus lying?
......

I just finished my cummins conversion into a 78 F350 and curious to what people are REALY getting mileage wise...
Yes, most of them are lying.

And to be honest - the guy who replied above me probably isn't giving factual numbers either.
 

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I'll let you know my numbers in a few months :laughing:

It's a 2wd CCLB 5speed with 3.54 gears.. It will weigh between 6500-7000lbs depending on how I keep the tool box (and if I find an aux fuel tank). I'm not expecting much over 17mpg on the hwy.. But who knows! :confused:
 

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I know on Andy's rig if you run it over 70 MPH it only gets 18-19. Keeping it at or just under 70 is a sweet spot. Can't claim it on towing though. Pulling a jeep on a car hauler I have gotten as bad as 9, think it is around 12-14 avg but I can't remember for sure. I don't see why you shouldn't get 17 or higher if you keep your speed down.
 

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Discussion Starter #8
My truck weighs about 5000. It is a 1stgen 12 valve with an S300 turbo and 4 inches down pipe. No pump mods except 3200 governor spring.

DRM , I got 24 mpg (2wd truck) on the first tank... Kinda couldn't believe it as I never believed all those people that claimed twenty plus. Possible I miscalculated, will see on the next tank...
:stirthepot:
 

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I also have a first gen regular cab 2wd Dodge. Unloaded on the highway I can get over 20 mpg. Just towed to Harlan and got right around 15 mpg there and back.

My sweet spot is also around 70. Mods : compressor housing upgrade, BHAF, fuel turned up, 4 inch exhaust all the way back, 47rh swap with goerend parts, timing bump, dennyt fuel pin.

Edit: forgot to mention 3.07 gears
 

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Discussion Starter #12
Only towed once so far. If I can get 15-18 towing, I will be ecstatic! 7-9 with the 460 was starting to hurt.....
 

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I'd say most are full of shit (and this subject has been discussed multiple times). I have a stock 1st gen W250 and get about 17mpg overall average. I really need to hook a trailer to it all the time so I too can get 30mpg.:shaking:
 

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My 98 5 speed 2WD 12 valve would consistently get 19 - 20 on the highway unloaded if I really paid attention to how I was driving and kept my foot out of it. It would also get as low as 15 if I drove it like retard around town.
 

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Those are factual numbers.

But let me guess, my word isn't good enough for you.
No, it's not. And no offense to you specifically, but I don't believe anything but mileage logs, and numbers corrected for the odometer being off.

The only consistent numbers above 20mpg I have seen proof of were 2wd trucks in flatlands that are never driven above 70mph.... usually more like 55mph.
 

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Discussion Starter #16
Well, mine has no speedometer because the NV4500 I used had no provision for one.
It is a 2wd and I kept it at 60. Time will tell, but to run 65, took a few more pounds of boost. That means more fuel....
 

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Well, mine has no speedometer because the NV4500 I used had no provision for one.
It is a 2wd and I kept it at 60. Time will tell, but to run 65, took a few more pounds of boost. That means more fuel....
So I assume no speedo means no odometer either? How do you know how many miles you traveled? How do you know your odometer is correct?
 

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97 3500 4x4 auto, 4.10's about 16-17 hwy. Anyone claiming over 20 is flat out lying or is horrible at math. My 02 24 valve would only due about a mile per gallon better.
 

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Discussion Starter #19 (Edited)
Gps , neat little modern marvel.....

That's why I asked , not sold on the accuracy of those either....but I trust those more than the speedometer.
 

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My 95 would get about
19 after the timing was done , stock 4x4 dually extracab auto 3.54 gears. Haven't checked it in a while. My 97 same truck with 5 speed , 4.10s and 315 tires is getting about 14. Checked it a few times these last few weeks.
 
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