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how bad does the 3.92 gearing affect MPG?

Willwork4truck

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I average 13-14 in town, 15-19 on the highway. I have 3.92 and the off-road package, I think the more aggressive tires might be why I get such terrible mileage. I don't drive very hard, but I always get terrible mileage. My friend has the same truck as me just without the off road package and gets 3-4mpg better than me on the highway, it's frustrating!
Yeah that would be frustrating however ORP/gearing/tires will do that.
For even more frustration, try the exact same drivetrain and get a 2 or 3 mpg difference, like my son and I experience with our 3.21 non ET hemi 4x trucks.
Him 14 mpg in town, me 16-17 in town. Him 18 highway, me 21-22mpg...
 

AtlasRam1500

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AtlasRam1500

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2019 Limited with Air suspension Nitto Ridge grappler 285/55/22 with Revel link front and daystar space. Replaced Upper control arms with the Mopar 2In level kit uca drives very close to oem ride smooth just a slightly more bounce but not bad picture is taken in normal mode
 

moparleo51

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2019 ram with off road group and rebel wheels on 3.92 gears . And I average 14-16 in town using 89 octane gas. It does do better on highway as the truck doesn't need to shift as often. And I get about 16-18 .

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BowDown

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2020 Limited 2wd with eTorque and 3:21's. I get 17.5-18 or 420-430 miles per tank in 80/20 city highway driving. On a recent highway drive, I was at 24mpg @70mph
 

iLikeTurtles

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2019 Limited with Air suspension Nitto Ridge grappler 285/55/22 with Revel link front and daystar space. Replaced Upper control arms with the Mopar 2In level kit uca drives very close to oem ride smooth just a slightly more bounce but not bad picture is taken in normal mode
Did thry try and say anything about impacting warranty work? I cannot imagine it impacting it other than, premature compressor failure for some BS reason of supppsed bag inflation difference which there shouldnt be, or foreign contaminants entering system from disconnecting. Both BS.
 

AtlasRam1500

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Did thry try and say anything about impacting warranty work? I cannot imagine it impacting it other than, premature compressor failure for some BS reason of supppsed bag inflation difference which there shouldnt be, or foreign contaminants entering system from disconnecting. Both BS.
I let the dealership install it warranty is still good not an issue. The airbag inflation has not change from stock to level what raise it was a space on top of the airbag strut. I had a 2014 ram that had airbag and did the same adding the space with links. the dealership installed and about 2 year the passenger side airbag failed the dealership replaced both front as a set for me. never had any problems with the dealership.

When you disconnect the system at the entry level. this is when the bag is fully decompress, so there nothing that will enter the system because of a check value. never had a problem plus if i need to service my tank i have nitrogen available at my work
 
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iLikeTurtles

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I will have to inquire with my dealer. They are being finnicky about what seems to be a stuck lifter and are pointing at a single injector making noising but will not act on it.
 

iLikeTurtles

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I let the dealership install it warranty is still good not an issue. The airbag inflation has not change from stock to level what raise it was a space on top of the airbag strut. I had a 2014 ram that had airbag and did the same adding the space with links. the dealership installed and about 2 year the passenger side airbag failed the dealership replaced both front as a set for me. never had any problems with the dealership.

When you disconnect the system at the entry level. this is when the bag is fully decompress, so there nothing that will enter the system because of a check value. never had a problem plus if i need to service my tank i have nitrogen available at my work
Think you could fit mud flaps with those tires? I presume turning left or right there will be too little room when you turn the tires
 

NorthernArea51

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In the 13’s around town. 16-18 hwy...

On my 3.92 I am running a front end level and 33” rebel wheels. I found the level had the biggest effect on the mpg. If you’re going to leave it stock you’ll see much better numbers from your 3.92.


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brettguercio

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I have 3.92 I dive it like I stole it lots of highway driving average mpg 16.5 my next truck will be 3.21 with 33 gallon tank
 

BowDown

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Driving styles vary and have an impact but its clear that 3.92 have a significant impact on fuel mileage over 3.21's, its far more than 1-2 mpg. You are dealing with 20% more gear/higher rpm
 

iLikeTurtles

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Driving styles vary and have an impact but its clear that 3.92 have a significant impact on fuel mileage over 3.21's, its far more than 1-2 mpg. You are dealing with 20% more gear/higher rpm
I disagree. Driving characteristics play far more of an impact. Gear ratio does not play a 1:1 effect on fuel mileage like it does with cruise RPM I believe, so no where near 20% decrease on 17 combined MPG due to gearing.
 
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BowDown

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I disagree. Driving characteristics play far more of an impact. Gear ratio does not play a 1:1 effect on fuel mileage like it does with cruise RPM I believe, so no where near 20% decrease on 17 combined MPG due to gearing.
3.21 to 3.92 is a 19-20% increase in rear gear, cruise speed at 70 is 1500 rpm vs 2000 is a 25% increase in engine rpm (more rpm = more fuel)
most people with 3.92 gears are claiming 14-15/6 mpg in the city and 18ish highway vs 3.21 getting 17-18 city and 23-24 highway as referenced in this thread.
City: 14-15/6 (3.92 mpg) vs 17-18 (3.21mpg) = 19-20% difference
Highway: 17-18 (3.92 hwy mpg) vs 23-24 (3.21 mpg) = 24-25% difference.
Combined 16.25mpg avg for 3.92 and 20.5mpg for the 3.21 + ~20% difference

Driving style does play a big role in city to a point but not on the highway. 20% isn't a big number, its 3-4mpg difference, significant over a tank.
A better question for the OP might be mileage per tank 3.21 vs 3.92
I average 420-430 miles a tank with my combined driving of 80/20 city to hwy
 

RHeller1

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3.92 gears 4wd stock everything. last road trip was a hand calc average of 21.3 mpg. that was 80% highway running 68-70mph. I routinely get mid 18's combined city/highway.
 

iLikeTurtles

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500 rpm does not mean 20% fuel mileage reduction. If i go up 2500rpm will have a 100% reduction in fuel mileage?

I get 14.5-14.8mpg combined with my 3.21 non etorque.
 
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