This MPG is why I bought the 3.21

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Yeah, but we can still fight about it for, what, like 5 pages or so?

I genuinely like California. Californians ruin much of the experience, mind you, but it's still worth the visit. :D
Nah Doc, I don't get butthurt like some do unless it's a direct insult lol ... banter is fun especially on forums where you can go back and forth with others and still have fun ... @Okie345 for some reason didn't like it when he was corrected a while ago ... oh well lol, that's what happens with kids that were born in the 90s lol
 

Dusty

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Couldn't resist after seeing a bunch of negative posts on the 3.21. I get why this forum is so lopsided, it's an enthusiast forum so many will be drawn to the 3.92.

But this week I just crushed my best record to date (which was 2 years ago). Back then the best I got was 9.4 l/100 km = 25 mpg. This week, my truck displayed this little goody on the dash:

8.4 = 28 mpg

3 hours 100% freeway driving, avg of 103 km/h, with a light tail wind, MDS disabled, mix of 89 and 91 octane fuel, probably some ethanol in there but cant be certain of the amount.

Reset meter, hopped on the freeway, and snapped pic after 3 hours on the off ramp. So yes, all ideal conditions but it's still far better than anything I've seen with the 3.92. And I probably won't see that again ever, but there is no doubt the MPG savings of the 3.21 are real.

View attachment 497724
You are not alone.

Column definitions (L to R): Date, miles at fill, gallons used, MPG, comments, EVIC MPG, deviation (mpg v. EVIC mpg)

Regards,
Dusty

2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 74702 miles
 

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ramffml

ramffml

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You are not alone.

Column definitions (L to R): Date, miles at fill, gallons used, MPG, comments, EVIC MPG, deviation (mpg v. EVIC mpg)

Regards,
Dusty

2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 74702 miles

That is epic, thanks for posting some real data!

So I guess all the comments like "the evic gets more and more out of whack as your mpg increases" were just sour grapes. I suspected as much, but can't argue with the data.
 

gfh77665

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Huh? 3.21 keeps the RPM's as low as possible.


Nope.



Ahhhh....


It really doesn't. My truck literally spends 98% of its engine runtime in 8th gear.


It doesn't.


I'm not sure about 3.55. On the one hand it's completely not needed, transmission shifts are about 400 to 500 RPMs apart so there is never any lack of power at any point with the 3.21. On the other hand, it's the only gear ratio that puts you at completely different RPMs while towing. The 3.21 and 3.92 will both be at approx 2300 RPMs while towing my trailer at 63 mph. The 3.55 would be a few hundred higher or lower, and that might be either wasted fuel or feel nice and strong. Hmm.
I bet you never owned a 3.55, so you want to call me out?

3.21 gearing WILL make the trans work more. Shift points WILL be different. I don't care who you are, that's physics.
 
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I bet you never owned a 3.55, so you want to call me out?

3.21 gearing WILL make the trans work more. Shift points WILL be different. I don't care who you are, that's physics.
Don't waste your time, he is a serious 3.21 homer lol ... he thinks everyone is bashing and being negative about the 3.21s and thinks everyone is or needs to worry about MPG ....he doesn't take into account that not everyone is stock or that everyone has different driving habits. Even geographical location can impact fuel efficiency ...
 

Dusty

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That is epic, thanks for posting some real data!

So I guess all the comments like "the evic gets more and more out of whack as your mpg increases" were just sour grapes. I suspected as much, but can't argue with the data.
The EVIC thing is lacking diagnostic logic. If you look at the design the PCM receives input from a potentiometer in the fuel pick up. The PCM simply looks at reported mileage and the register fuel level to determine an MPG reading. There is no algorithm. The PCM computes on direct reads. Something would have to be inconsistent in either data in order to realize an internal inaccuracy.

The deviation from 'true' (hand calculated) to the EVIC value is much more logically based on inaccuracies of the fill. A lot of people are not conscious of how many times they squeeze the nozzle. I try to always use the same pump at my neighborhood Sunoco as the nozzle cut-off pressure and the pad level should be consistent day-to-day. However, it's not always practical to do that, hence at other locations I'm getting either short fills or over fills for either of the two mentioned reasons.

Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 74702 miles
 
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ramffml

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I bet you never owned a 3.55, so you want to call me out?

3.21 gearing WILL make the trans work more. Shift points WILL be different. I don't care who you are, that's physics.

You need to read your post again, and what I wrote back.

We're not arguing whether the 3.21 will break 8th gear before the 3.55. Of course it will. I'm telling you the 3.21 does not have an "issue" downshifting too often, in other words, the hemi has more than enough torque for the 3.21 to hold 8th on the freeway.

So there is a difference between the "physics" (yes the 3.21 will downshift earlier), and "does the 3.21 have an issue maintaining 8th gear on the highway and is it constantly popping up and down between 7th and 8th". You're correct on the physics, but I'm telling you it's not an issue. (Again, you don't own one. Right? You kind of need to drive one for a while to make that call on whether it's too busy).

As for your "wear and tear" comment (3.21 vs 3.92), the 3.21 will ocassionaly downshift an extra time or two on the freeway, but remember the 3.92 will be more busy in the city.
 
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ramffml

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Don't waste your time, he is a serious 3.21 homer lol ... he thinks everyone is bashing and being negative about the 3.21s and thinks everyone is or needs to worry about MPG

Point out where I said everyone needs to worry about MPG. I said: this is why I purchased the 3.21. Personal decision. But yes, most people, the vast majority, are better off with the 3.21

....he doesn't take into account that not everyone is stock or that everyone has different driving habits.
Not true, the Rebel is a great candidate for the 3.92 if you offroad it. Obviously if you want a bro truck the 3.21 will be more lethargic with bigger tires. Very few people mod their truck all things considered. Most run to the store in stock, or with a few mudflaps or tunneau cover or stuff like that.

Even geographical location can impact fuel efficiency ...
This has no bearing on this particular discussion unless you think all the 3.21's live in one corner of the earth and the 3.92s in the other and somehow the 3.92s are getting the short end of the stick. Maybe you think the 3.92s are closer to the equator or something and spend more time driving vertically up the steeper part of the globe? You tell me.
 

Docwagon1776

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V6 guy has entered the chat. All your MPG thread up to this point was meaningless. MEANINGLESS!

 

gfh77665

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As for your "wear and tear" comment (3.21 vs 3.92), the 3.21 will ocassionaly downshift an extra time or two on the freeway, but remember the 3.92 will be more busy in the city.
Wrong, wrong, wrong. The 3.92 & engine will have an easier time in the city. Thats exactly where it shines, moving a load (the truck) off the line.

If you want a physics lesson you can understand, get a 10 speed bike. Pedal from a stand still in first gear. Its easy to move the bike. Thats like the lower gear 3.92. Then come to a complete stop and put the bike in 3rd gear, and start out. Significantly harder to pedal from a stop, isn't it? The extra stress and effort you feel in your legs starting out from 3rd gear is indicative of the additional stress and effort the truck has to get moving with taller (numerically smaller) gearing like the 3.21.
 
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ramffml

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Wrong, wrong, wrong. The 3.92 & engine will have an easier time in the city. Thats exactly where it shines, moving a load (the truck) off the line.

If you want a physics lesson you can understand, get a 10 speed bike. Pedal from a stand still in first gear. Its easy to move the bike. Thats like the lower gear 3.92. Then come to a complete stop and put the bike in 3rd gear, and start out. Significantly harder to pedal from a stop, isn't it? The extra stress and effort you feel in your legs starting out from 3rd gear is indicative of the additional stress and effort the truck has to get moving with taller (numerically smaller) gearing like the 3.21.

Dude, stop and think. In order for the 3.92 to work "easier", it needs to use more gears. Therefore, by definition, it's more "busy".

I'm too lazy to run the math for you, but there comes a point where the 3.92 is in 8th and the 3.21 is still in 7th. Therefore it used 8 gears to get to the same speed that the 3.21 used 7 gears for. Yes. Your 3.92 is more busy in the city, so your "oh horrors look at the downshift" argument is completely negated by the fact that in the city its the 3.92 that is using more gears to get to the same speed.

You're completely confusing "easy" vs "busy".

And let me remind you that this is such a stupid argument because it has 400 hp. Both trucks can get to 60 in a few seconds, with only a fraction of a second difference. Neither truck is stressing the transmission. Neither truck is going to kill it by downshifts or upshifts.

You're arguments are nonsense. But if you want to talk about the 3.21 being more busy with the downshift on the freeway, you need to accept the flipside of the coin which means the 3.92 is more busy in the city, using more gears to accelerate to the same speed.
 

star_deceiver

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The poster you’re arguing with is someone with the 3.6 and 3.55s. It will downshift into 7th if you fart the wrong direction in the cab….

With over 11:1 compression on 87, the 3.6 will not stay at low rpms regardless of the number of teeth on the pinion. You can lug a 5.7. The computer will let you. You can’t lug a 3.6 no matter how hard you try.
 

gfh77665

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Dude, stop and think. In order for the 3.92 to work "easier", it needs to use more gears. Therefore, by definition, it's more "busy".

I'm too lazy to run the math for you, but there comes a point where the 3.92 is in 8th and the 3.21 is still in 7th. Therefore it used 8 gears to get to the same speed that the 3.21 used 7 gears for. Yes. Your 3.92 is more busy in the city, so your "oh horrors look at the downshift" argument is completely negated by the fact that in the city its the 3.92 that is using more gears to get to the same speed.

You're completely confusing "easy" vs "busy".

And let me remind you that this is such a stupid argument because it has 400 hp. Both trucks can get to 60 in a few seconds, with only a fraction of a second difference. Neither truck is stressing the transmission. Neither truck is going to kill it by downshifts or upshifts.

You're arguments are nonsense. But if you want to talk about the 3.21 being more busy with the downshift on the freeway, you need to accept the flipside of the coin which means the 3.92 is more busy in the city, using more gears to accelerate to the same speed.
 

gfh77665

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OK like someone said, you are a 3.21 "homer",....DUDE. I understand the profound effect confirmation bias is having on you here. I have no need to argue with you because I don't give a flip what you drive. However, you should know I have a very respectable technical background. You really are arguing with the wrong person right now. If you want to believe the 3.21 is the superior gearing, just because you bought it, have at it dude.
 

Wild one

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Wrong, wrong, wrong. The 3.92 & engine will have an easier time in the city. Thats exactly where it shines, moving a load (the truck) off the line.

If you want a physics lesson you can understand, get a 10 speed bike. Pedal from a stand still in first gear. Its easy to move the bike. Thats like the lower gear 3.92. Then come to a complete stop and put the bike in 3rd gear, and start out. Significantly harder to pedal from a stop, isn't it? The extra stress and effort you feel in your legs starting out from 3rd gear is indicative of the additional stress and effort the truck has to get moving with taller (numerically smaller) gearing like the 3.21.

OK like someone said, you are a 3.21 "homer",....DUDE. I understand the profound effect confirmation bias is having on you here. I have no need to argue with you because I don't give a flip what you drive. However, you should know I have a very respectable technical background. You really are arguing with the wrong person right now. If you want to believe the 3.21 is the superior gearing, just because you bought it, have at it dude.
And just what is your technical background? Little tidbit for you RPM and Friction are the biggest killers of an engine and driveline components,guess what goes hand in hand with deeper gears.Load on those same components not so much. Just saying,lol.This is really starting to get boring with the he said/she said type mentality in this thread.Have a good day gentlemen.
 
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ramffml

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OK like someone said, you are a 3.21 "homer",....DUDE. I understand the profound effect confirmation bias is having on you here. I have no need to argue with you because I don't give a flip what you drive. However, you should know I have a very respectable technical background. You really are arguing with the wrong person right now. If you want to believe the 3.21 is the superior gearing, just because you bought it, have at it dude.

Ah, the ole "I'm right and your mother smells like elderberries" logic.

I'm truly in awe of your technical background, but only because despite it you still don't know how gears work.
 

gfh77665

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And just what is your technical background?
37 years of analytical chemistry, liquid and gas chromatography, and mass spectrometry. And 12 hrs of physics in college.

And now, just what is YOUR technical background?

You and the 3.21 "homer" need to speak up and tell us all what you got.
 

gfh77665

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I'm truly in awe of your technical background, but only because despite it you still don't know how gears work.
37 years of analytical chemistry, liquid and gas chromatography, and mass spectrometry. And 12 hrs of physics in college.

And now, just what is YOUR technical background?
 
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ramffml

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37 years of analytical chemistry, liquid and gas chromatography, and mass spectrometry. And 12 hrs of physics in college.

And now, just what is YOUR technical background?

13 hrs of physics in college. I also took basket weaving!
 
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