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General Prelaunch Discussions about the 6.7L This section has now been archived, and has been left here for general information purposes only. Please post all new topics in the appropriate 4th Generation section.
 
 
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Old 11-01-2007
jrbarbely jrbarbely is online now
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Default Best gear ratio for fuel mileage?

I was wondering what gear ratio provided the best fuel mileage running empty. 3.73 will provide a lower engine rpm but 4.10 will let the engine work less but at a higher RPM.

And just so everyone know, I want to buy a 2500 soon and i'm trying to educate myself to make a good decision. It is my first new car and it is a whole lot of money to be unsatisfied.
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Old 11-01-2007
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Default Re: Best gear ratio for fuel mileage?

3.73 for fuel milage, 4.10 for power [img]/forum/images/%%GRAEMLIN_URL%%/wink.gif[/img]
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Old 11-01-2007
MikeyB MikeyB is offline
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Default Re: Best gear ratio for fuel mileage?

You can get a 3.42 with the G56 manual.

MikeyB
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Old 11-01-2007
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Default Re: Best gear ratio for fuel mileage?

NOT 4.10'S
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Old 11-01-2007
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Default Re: Best gear ratio for fuel mileage?

As I mentioned in your other thread, I am not disputing that while driving empty on flat highway the 3.73's will get slightly better mileage, however the difference is not near as much as many would like to believe. I have seen plenty of these CTD's with 4.10's that get 20 or better empty/highway, I have seen plenty of CTD's with 3.73's get mid-upper teens in the same conditions. When you get to the upper highway speeds aerodynamics in a much larger factor in the mileage picture.

Also as I mentioned in your other thread, a good example is CTD's with a gear vendor overdrive that drops RPM by more then 500 vs the appx 200RPM drop you get with 3.73's vs 4.10's. Anyone I know with the gear vendors is lucky to get appx 1MPG better in overdrive running empty on highway. If that is the gain with a 500rpm drop at high speeds (say from 2500 down to 2000rpm), you certainly can't expect to see anywhere near that with a 200rpm drop that 3.73's would provide vs the 4.10's.

Would the 3.73's net better mileage on the highway, most likely yes. All I am saying is when you factor overall mileage the difference will be very small. As much as you indicate that you want a new 5.9 vs the 6.7 in your other thread I am simply suggesting the difference is not one to worry about if you find a 5.9 equipped the way you want.
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Old 11-01-2007
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Default Re: Best gear ratio for fuel mileage?

Some calcuations to consider...

Even if you get 1MPG better with 3.73's, which is quite a stretch, you would save appx $183 a year if you drive 20,000 miles in that year.

Using some assumptions here is an example:
4.10 Gear - 20,000 miles / 18MPG = 1,111 gals
3.73 Gear - 20,000 miles / 19MPG = 1,053 gals

58gals saved @ $3.159 per gal = $183.22 saved over $20k miles

Not a whole lot if it gets you in the 5.9 that you want, not to mention that you will get a truck that will pull better should the situation ever arise.
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Old 11-01-2007
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Default Re: Best gear ratio for fuel mileage?

you should consider the speed you are likely to drive. when you get into the higher rpms your mpg take a big drop. i have 4.10 in my truck and if i can keep it around 65 and under on the highway mpg are good, faster than that and they go down fast

that is running empty
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Old 11-01-2007
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Default Re: Best gear ratio for fuel mileage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kooch</div><div class="ubbcode-body">you should consider the speed you are likely to drive. when you get into the higher rpms your mpg take a big drop. i have 4.10 in my truck and if i can keep it around 65 and under on the highway mpg are good, faster than that and they go down fast

that is running empty </div></div>

That is more a funtion of aerodynamics and drag than gearing... especially with a truck like this that pushes a lot of wind.

The same is true of my truck and 3.73's... I loose at least 1mpg for every 5mph over 65.
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Two '05 Kawasaki Prairie 700 4x4 ATV's (his & hers) and a '06 Kawasaki 50cc for the daughter
'66 Mustang Coupe, Modified 302/C-4
'09 Ford Escape Limited (hers)
 

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