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Some Real World MPG Numbers

CogitoErgoLevo

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Is everyone running the recommended tire pressure on the door jam or the tire itself? I have the 275/65/18 wildpeak and at 38psi they look slack,so I bumped them to 43psi. The sidewall calls for 50psi for max load.
I run 90 octane non-ethanol and evidently they dropped the first of the summer gas last week. I’m up to 17.5mpg and hope to break 18 in a few weeks.
I run my stock 275-55-20 at 42 PSI instead of recommended 36 PSI. My truck feels better on highway with higher tire pressure.
I have 2000 miles on the truck and I am now getting 18mpg combined, 70% Highway / 30% City. Up from 14mpg on its first tank.
My combined mpg might go up to 19mpg which would match EPA rating for 3.92 ratio Hemi with eTorque... or it might stay at 18mpg or so.
 

BowDown

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I run my stock 275-55-20 at 42 PSI instead of recommended 36 PSI. My truck feels better on highway with higher tire pressure.
I have 2000 miles on the truck and I am now getting 18mpg combined, 70% Highway / 30% City. Up from 14mpg on its first tank.
My combined mpg might go up to 19mpg which would match EPA rating for 3.92 ratio Hemi with eTorque... or it might stay at 18mpg or so.

Strange, I accidentally over inflated my tires (bad tire pressure gauge) and agree that the truck seemed to drive better at 40-41psi
 

RAM Patriot

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Ram 1500 BigHorn 5.7 HEMI
4X4 Quad Cab 3.21


Installed Rebel Wheels & Tires at 1,252 miles on the odometer so I have been running these wheels for the bulk of the life of the truck.
I would probably be getting at least 1-2 MPG better on the stock wheel and tires.

I also have run run non-ethanol fuel for the life of the truck.

Switched to Super 90 octane non-ethanol at 15,000 miles and noticed not only an improvement in mileage but also in performance.

I track my mileage on an App called Car Care by Karl Becker

RAM_PATRIOT_MPG.png
 

silver billet

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I hear you, check your rpm at 70 mph, I'm ~1400

You have a couple posts on this since my last one so I'll just reply here. You're making the mistake in assuming that both trucks will be in the same numerical gear for the same mph. But they won't be. When you do the math, the trucks have pretty much identical gear ratios to choose from.

If 3.21 requires the 3.21 gear ratio (6th) for a given speed/load, then the 3.92 will be using the closest gear ratio it has available as well, which happens to be 3.2144 (7th).

If 3.21 requires the 6.86 gear ratio (3rd), then the 3.92 can use 6.74 (4th).

And so on.

Only when both trucks are in final gear ratios for each truck do we have a problem; because then the 3.21 is using 2.0544 whereas the 3.92 is stuck using 2.508, a signifcant difference of about 400 rpms. That will eat up the gas over long runs, giving the 3.21 its highway cruising advantage.
 

BowDown

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You have a couple posts on this since my last one so I'll just reply here. You're making the mistake in assuming that both trucks will be in the same numerical gear for the same mph. But they won't be. When you do the math, the trucks have pretty much identical gear ratios to choose from.

If 3.21 requires the 3.21 gear ratio (6th) for a given speed/load, then the 3.92 will be using the closest gear ratio it has available as well, which happens to be 3.2144 (7th).

If 3.21 requires the 6.86 gear ratio (3rd), then the 3.92 can use 6.74 (4th).

And so on.

Only when both trucks are in final gear ratios for each truck do we have a problem; because then the 3.21 is using 2.0544 whereas the 3.92 is stuck using 2.508, a signifcant difference of about 400 rpms. That will eat up the gas over long runs, giving the 3.21 its highway cruising advantage.

I didnt make that mistake but none of that changes the fact that the 3:21 truck fuel mileage is superior to the 3:92 while the performance trade off is minimal, id bet 1/10 in the 1/4 mile. Agree to disagree and I'll keep getting 18 in the city and stop and go highway traffic(y)
 

CogitoErgoLevo

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There is about a 10% difference in mpg between 3.21 and 3.92 on highway. Which is around 2mpg.
I am not sure I would use the word "superior" for 10%.
Sounds to me that you are having confirmation bias.
 

silver billet

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Agree to disagree

I can agree to stop arguing (y) I think we DO agree the 3.21 is the better choice all around. I haven't seen official 0 to 60 numbers but it wouldn't surprise me to see the 3.21 holding its own fairly well there too.
 

BowDown

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There is about a 10% difference in mpg between 3.21 and 3.92 on highway. Which is around 2mpg.
I am not sure I would use the word "superior" for 10%.
Sounds to me that you are having confirmation bias.

What would you call an extra 46 miles per tank?
If it's not superior, why are so many 3:92 owners complaining about fuel mileage? Some of you are reporting 13-14 mpg, thats 4-5 mpg less.
Also, I've had a 3:92 truck, the fuel mileage sucked bawls, this truck is a solid 5mpg better with the same driving on the same routes; 300 miles per tank vs 420 miles per tank city driving. That's not confirmation bias, that's fact
 
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BowDown

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I can agree to stop arguing (y) I think we DO agree the 3.21 is the better choice all around. I haven't seen official 0 to 60 numbers but it wouldn't surprise me to see the 3.21 holding its own fairly well there too.

Neither is setting the world on fire with 0-60. I've read 14.7 1/4 miles ets (don't know which gear) which is faster than I thought and decent but unless I was towning really heavy loads, I'd still opt for the 3.21.
I towed a 2300 lb uhaul trailer loaded with 2900lbs of stone this weekend and the truck performed better than my 3:92 truck did. It did mis identify the trailer though, was closer to 20" which it correctly Id'd when I was backing up

1617668851069.png

Still overall impressed with this truck everytime I drive it
 

BowDown

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I can agree to stop arguing (y) I think we DO agree the 3.21 is the better choice all around. I haven't seen official 0 to 60 numbers but it wouldn't surprise me to see the 3.21 holding its own fairly well there too.


2019 Ram 1500 Laramie Crew Cab 4X4 0-60 mph 6.1Quarter mile 14.7 Compare
2019 Ram 1500 Laramie Sport Crew Cab 4X4 0-60 mph 6.4Quarter mile 14.9 Compare
2019 Ram 1500 Limited Crew Cab 4X4 (eTorque) 0-60 mph 6.2Quarter mile 14.8 Compare
2019 Ram 1500 Limited Crew Cab 4X4 0-60 mph 6.5Quarter mile 15.0 Compare
2019 Ram 1500 Long Horn Crew Cab 4X4 0-60 mph 6.3Quarter mile 14.8 Compare
2019 Ram 1500 Rebel Crew Cab 4X4 0-60 mph 6.4Quarter mile 15.0 Compare
2019 Ram 1500 Rebel Quad Cab 4X4 0-60 mph 6.4Quarter mile 14.9 Compare
2019 Ram 1500 Tradesman Crew Cab 4X4 0-60 mph 7.5Quarter mile 15.8 Compare
2019 Ram 1500 Big Horn Quad Cab (eTorque) 0-60 mph 5.9Quarter mile 14.4 Compare
2019 Ram 1500 Big Horn Quad Cab 0-60 mph 5.9Quarter mile 14.4 Compare
2019 Ram 1500 Big Horn Crew Cab 4X4 0-60 mph 8.5Quarter mile 16.5 Compare
2020 Ram 1500 Crew Cab EcoDiesel 4X4 0-60 mph 7.9Quarter mile 16.0 Compare
2021 RAM 1500 Rebel TRX Crew Cab 0-60 mph 3.9Quarter mile 12.5


 

IvoryHemi

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My 5.7/8HP70/4WD Durango with 3.09 axle got 13-14 mpg. The 5.7 Hemi is just a thirsty pig
 

IvoryHemi

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It’s very difficult to compare apples to apples MPG between these trucks because of so many variables

- driving style
- driving type
- weather conditions
- BSG vs non-BSG
- 4x2 vs 4x4
- Eco on vs Eco off
- wheel/tire combo
- gas quality
- elevation
- curb weight varies by 800 lbs
- and yes 3.21 vs 3.92
 
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silver billet

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It’s very difficult to compare apples to apples MPG between these trucks because of so many variables

- driving style
- driving type
- weather conditions
- BSG vs non-BSG
- 4x2 vs 4x4
- Eco on vs Eco off
- wheel/tire combo
- gas quality
- elevation
- curb weight varies by 800 lbs
- and yes 3.21 vs 3.92

It's actually quite easy if you own a 3.21. Because we can test our truck in 8th and 7th and look at the difference; that difference is what the exact same truck with a 3.92 would get. Only minor detail is that MDS would have to be disabled in both tests, because in order to run the 3.92 simulation in 7th, we'd have to use the gear lockout to prevent an upshift to 8th. As long as we run the 3.21 without MDS in both tests it will directly compare though.
 

IvoryHemi

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It's actually quite easy if you own a 3.21. Because we can test our truck in 8th and 7th and look at the difference; that difference is what the exact same truck with a 3.92 would get. Only minor detail is that MDS would have to be disabled in both tests, because in order to run the 3.92 simulation in 7th, we'd have to use the gear lockout to prevent an upshift to 8th. As long as we run the 3.21 without MDS in both tests it will directly compare though.

That would be making the assumption that the axle ratio is the only variable.
 

theblet

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Who cares about 1/4 mile times in these trucks? I don’t it’s not a challenger. 🤷🏻‍♂️
 

JasonLBess

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And switching from the factory 32” tires to 34” tires drops the rpms in a 3.92 equipped truck by right at 200 rpms at 70.
So would going to a 34” tire with a 3.92 have the potential to increase mpg at highway speeds? Or would the added weight negate the effect?
 

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