Ok, I'm looking to improve gas mileage, I do 90% highway driving, so i am considering swaping my 3.92s for 3.21s, My question is, will my truck be able to handle this? It's a 98 with the 5.2 auto. My old ram had the same motor/trans, and it managed 18 mpg on the highway with 3.55s, so i'm hoping for 20 on the highway instead of the 14.3 I am getting at 65-70mph. What are ya'lls input?

 

It is going to be sluggish in town driving which will cause it to work harder and in the end get you no where. I wouldnt go any lower than 3.55's. I have the same truck and I only get like 13 average.

 

I'll go with 355s then, thanks for the input. That should still be a nice improvement from what i'm getting. along with a computer tune

 

Dont expect it to be a big improvement. You might see a mpg increase. I just got a sct tuner and I havent done a whole tank yet but I went from 50miles on a 1/4 tank to about 80 miles on a 1/4 tank.

 

Let me know how it goes for you, SCT is the one i'm considering. I'm about to be driving from Mississippi to Texas alot for the next year, that's why i'm working on getting the gas mileage up quick. Most anything is better than 14.3mpg on the highway, thats rediculous for a 2wd

 

3.21 would be too high IMO, stick with 3.55s. You should be able to achieve at least 18MPG during strict freeway driving.

 

I have had it for a month now and I am very happy with it. I run the 93 tune on 89 gas and that is where I see the most mpg.

 

my mpg went to crap after my final tune, 15.5ish on highway. but i do go WOT alot, I dunno, i blame it on the 100F days.

 

Just as soon as my other truck sells, i'm doing the gear change and the SCT. I'll let ya'll know how it turns out. 18 would be LOVELY. And dodgeramguy85, I may try doing the same thing and see if it helps anymore. I'm for sure gonna play around with it a bit

 

Im sure its all those full throttle launches you are doing lol. When I do a cam ill need to get some crappy tires for my truck lol