3.55 Ratio verus 3.21 Difference in Fuel Effic

[CherryRed]

I doubt you will see a significant mileage difference between the two ratios. If the best mileage is your goal, you should also be looking at keeping the truck's weight down as well. Regular cab, short bed, base trim level, etc.

 

[kevperro]

I have a 4x2 regular cab short bed with the 3.21s. I carry around 500lbs in the bed of the truck and I'd buy the same configuration again. I have no idea how much difference the 3.55 would make but if you get a 4x4 crew cab which is heavier to start and carry around extra weight the 3.55 probably isn't a bad idea. I doubt once you buy it you will ever worry about it again whichever ratio you get.

And you get all kinds of people commenting on the engines. This is the Internet... you have to take them all with a grain of salt and use some common sense. Drive the configuration you want to buy before shelling out the money.

 

[rsdata]

I like my 2014 crew cab with hemi, 3.21 and 8 speed... doing 70-75 I get nearly 21MPG on hilly midwest terrain. I have hauled my 4500# travel trailer about 500 miles so far with no difficulty at all. Typical combined driving for me is 16+MPG, but I do like to put my foot into it on occasion. I luv the 32 GAL tank option... 500+ mile range if you do any hiway driving at all.

With less Hp on the 3.6, the 3.55 might be a better all-around choice... probably the reason you find so many of them on the lots.

 

[malatu]

I like my 2014 crew cab with hemi, 3.21 and 8 speed... doing 70-75 I get nearly 21MPG on hilly midwest terrain. I have hauled my 4500# travel trailer about 500 miles so far with no difficulty at all. Typical combined driving for me is 16+MPG, but I do like to put my foot into it on occasion. I luv the 32 GAL tank option... 500+ mile range if you do any hiway driving at all.

With less Hp on the 3.6, the 3.55 might be a better all-around choice... probably the reason you find so many of them on the lots.

Thanks for the input guys.

Actually, finding a hot steaming deal on a 2016 3.6L crew cab Laramie with the convenience package is a challenge! The one I was looking at was $36,300. The sticker on it was a little over $50K. It was sold while I was on the phone with the salesman. I was getting ready to place a deposit on it!

 

[TerraNewf]

This can turn into an ugly debate but there are several people on several forums that have traded v6's for hemis and seen a vast improvement in gas mileage. In my 2015 8 speed 3:21 with 120 ltr tank i can easily get about close to 750 kilometers to a tank, in the end i did not but my 4th hemi in the last 6 years to worry about gas mileage

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Just completed a 3300 kms trip, and after driving through Quebec which is pretty level I filled up in Napean my DTE showed 1160 kms. Other than that I'm getting mid 900's DTE. I also have the 121 litre tank.

 

[malatu]

Just completed a 3300 kms trip, and after driving through Quebec which is pretty level I filled up in Napean my DTE showed 1160 kms. Other than that I'm getting mid 900's DTE. I also have the 121 litre tank.

I gotta convert all that metric stuff to the Queen's unit of measurement!

 

[TerraNewf]

I gotta convert all that metric stuff to the Queen's unit of measurement!

1160 kms is 720 miles, mid 900's kms is roughly 590 miles

 

[catch 22]

Boy I'll say! I can get 23-24 mpg at a steady 45-50mph.......on a flat street.....with a tailwind.

going down hill......in neutral.....with 75 psi in the tires!

 

[satxwy]

I have a 4x2 Crew Cab with the 3.21 V6. It has no power issues, as long as you rev it a little this engine has plenty of pickup. I believe the torque curve is mostly flat from 1800 rpm upward. At 70mph I believe I run about 1600-1700 rpm. Cruise set to 77 I should be right about 1900-2000rpm.

With mixed driving and some hilly highways and into strong headwinds, I normally don't see worse than 22 mpg (hand calculated) on my normal route. On other highways more favorable for fuel economy I easily see 24. I've gotten the EVIC as high as about 28 over a hundred plus miles of relatively flat highway driving below 60 mph.

My only complaint is that the transmission is too eager to upshift, putting you at too low of an RPM to make much usable power, meaning you have to wait for a downshift to get much power. For that reason, if I bought again, I might look for a 3.55 ratio instead.


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[mcheath]

My RCSB 4x2 tradesman with the 3.6 and 3.21s gets pretty ridiculous mileage on the freeway. When I had the stock 17" wheels it would claim as much as 29.5mpg at 70mph. Slow it down to 55 and it jumped to as much as 33.5mpg. Long trips to the coast, flatland, mountains, hills, with some luggage averaged about 27mpg overall.

Town mileage has been around 18.0, and my commute, a mix, averages about 21.

I don't drive fast, and don't press the go pedal very hard.

It now has 20" wheels and mileage has dropped 1 or 2mpgs. Might be temporary as the tires are new and still breaking in.

The truck weighs 4500 pounds, confirmed on a scale.

As for if the 3.6 has enough power, I'm old enough to have driven the trucks of the 70s and 80s when "power" meant a 155 horsepower smog strangled V8 hooked to a sloppy 3 speed auto. Or 140 horsepower straight sixes, and even once had a GM 6.2l Detroit Diesel with all of 130 horsepower in a 3/4 ton 4x4. We towed, hauled and worked em', hard. They got terrible mileage, town or freeway, even that diesel was awful.

 

[TruckNut]

going down hill......in neutral.....with 75 psi in the tires!

Aw come on.....you don't like my figures? You can really milk these things but real world mileage average for me is 18-19 and that's it.

 

[catch 22]

Aw come on.....you don't like my figures? You can really milk these things but real world mileage average for me is 18-19 and that's it.

That's about what I get, driving like an idiot or running 80+ on the hwy., the mileage takes a hit. My RCSB Hemi Tradesman came with 3.21 open rear (***** peg leg), added Limited Slip w/3.55's, able to hold hi gear with out down shifting near as much and mileage is about the same.

 

[huntergreen]

How's that true??? I have the 3.6 and it's a great engine with plenty of power unless you haul or tow really heavy loads maybe..... I get 23-25 MPG cruising down the highway and I know the hemi doesn't get even close to that on the highway.

hemi wont meet that, but will come close on the hwy.

 

[THETANK]

hemi wont meet that, but will come close on the hwy.

I manage that kind of mileage @ 60 mph or 97k's

 

[SD38-2]

My 2014 express with the hemi and 6 spd has 3.55s.

 

[jasonw]

Gear ratio is usually on a tag inside the glove box if I remember correctly.

It's also on both axles (if 4x4). The rear one usually fades/falls off after not very long, but the front one is more protected. Here's the underside of the front differential from my 2013 when I had it.

Certain configurations are more common in some regions than in others.
I seem to remember the 3:55's with 8spd being a common configuration in 2014 when I bought my truck in Westetn Canada. Unless those were 2013's still on the lot, but I don't think that was the case.

The only time the 5.7L Hemi V8 was paired with the 3.55 gear ratio and 8-speed was 2013 (offered as an option). In 2014+, they cut down the options; the only way to get the 3.55 gear ratio with the 8-speed was with the V6 or diesel (bar a screw up from FCA of course, as there were some trucks geared incorrectly, where the build sheet/sticker said one gear ratio and FCA put in a numerically lower one).

 

[clh1220]

^^^^^^^^^^ that's correct.

 

[jag1886]

My 2014 Hemi 6 speed truck was suppose to have 3:55 but when I checked the axle housing it only had a 3:21.

 

[SitKneelBend]

My 2014 Express 3.6 4x4 says it's 3.55...I never double checked while I was under there though.

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