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Discussion Starter · #1 ·
Anyone got tips or tricks for squeezing mileage from a 2008 Long bed crew cab 6.7 G56 truck? For the time i have owned it i have driven it super gently trying to get decent mileage. I know my buddies with 5.9's get low 20's (even on their spicy tunes @500whp) with their common rails and my vp44 friends all seem to easily get mid-20's is there any way to be consistently in the 20's without doing anything illegal?

(already posted on 3-4 other forums just trying to get as much info as i can)
 

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Being really loose calculating miles and gallons really helps with those bragging claims.

Otherwise, lower the vehicle, fit smoothest and skinniest tyres on smoothest wheels you can (spoked wheels can create a heap of wind drag), fit the highest axle ratio that will get you a useable low rpm in top gear and use thinner fluids in gearbox and axles.
An aerodynamic cap can help too.
 

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Yes, you always need to be careful when guys are bragging about good fuel mileage. There can be lots of factors that filter into that. I don't see a 500 HP 5.9 getting into the low 20's very easily, at least not using that power. Now, if you're just cruising around and only using say 150 HP of that then maybe. One thing is more engine size of the 6.7, more smog controls, and more HP will equal worse fuel mileage. A friend of mine was driving Ford 7.3 diesels and decided to change to the Dodge. The best my 7.3 non turbo would do was 18 MPG. With the Dodge 5.9 he was getting around 22 MPG tops. If you can get into the low 20's I'd say that is very good but we hear of guys only getting 16-18 MPG especially on the newer trucks. More power isn't free.
 

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My 04 Ram 5.9 NV5600 (slightly better OD ratio than your G56) 4X4 3.73 ratio gets 20+ easily empty at 60-65mph. Driven carefully I can hit 23.
Stock ride height, running 285 LR F All terrain fairly mild tread tires, I did advance the timing just a little but still running stock intake and Ex with the cat. It always does better when the tires are worn out!
Pulling a 27' enclosed trailer with a 9.5 ' lance camper @ 21Klbs gross we get around 11.5 - 12 depending on wind-running from Central Oregon to Baja and back (1270 miles each way).
Jim
 

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Yes, you always need to be careful when guys are bragging about good fuel mileage. There can be lots of factors that filter into that. I don't see a 500 HP 5.9 getting into the low 20's very easily, at least not using that power. Now, if you're just cruising around and only using say 150 HP of that then maybe. One thing is more engine size of the 6.7, more smog controls, and more HP will equal worse fuel mileage. A friend of mine was driving Ford 7.3 diesels and decided to change to the Dodge. The best my 7.3 non turbo would do was 18 MPG. With the Dodge 5.9 he was getting around 22 MPG tops. If you can get into the low 20's I'd say that is very good but we hear of guys only getting 16-18 MPG especially on the newer trucks. More power isn't free.
My 1996 7.3 F350 CC 4x4 would get 21-22 mpg @ 65 mph on long trips, even with 250k miles on the clock.
Pushing it over 70 mph the fuel mileage would fall below 19.

The wife's 2013 3500 Ram gets 16-17mpg unless it is towing the horse trailer, then 14ish is the norm.
 

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Discussion Starter · #7 ·
Now, if you're just cruising around and only using say 150 HP of that then maybe. One thing is more engine size of the 6.7, more smog controls, and more HP will equal worse fuel mileage.
my only assumption is that just driving around town or towing a regular load you wont use all that power potential but that supporting upgrade stuff for the higher power makes the lower power daily use more efficient. sounds strange phrased like that but just think a higher rail pressure or an aftermarket optimized nozzle design can atomize better and be more efficient, if you had a bigger intercooler for your 500hp truck it may be more efficient on a daily application so the increased air density there could help too.
 
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