I've been reading a lot of threads lately about gas mileage, and have been wondering if taller gears or one of those overdrive units that go behind the tranny would significantly help? Especially if you are driving empty or towing a light load. Has anybody tried 3.55's or even taller gears? These engines make so much torque, it might not be too bad with "highway" gears.

 

What do you have now for gearing?

Theoretically more gears should = more mileage... however, we're not comparing a 6 speed to a 7 speed transmission, we're comparing a 6 sp tranny to adding weight, cost, to get an extra gear.

I'd say new axle ratios might be the best option.

 

I got better milage with the 3.73's and 37' then I do now with the 4.30's and 37's...

You have to be in the correct TQ range to take advantage of the RPM benifits. If the motor is fighting to keep up it will suck the fuel.

 

plus once you take a look at the price of swapping to taller gears your going to run so fast it will be scary. i got a quote on changing the gears out on my truck and it was over 1000. that was with my owning the gears. if you can press them in yourself go for it but if not. get ready for a big bill. if you factor out the price of fuel savings i dont think it will even out. ...just my .02

 

The drop in EGT's and the HP gain down low is why I did it... Just allows the motor to work in the proper range again.

 

exactly im in the same boat as you with the 37" tires. but i didnt see anything in his sig about having his truck jacked up. just iddn tknow why he wanted to do it other then milage

 

Just wondering how much a set or two sets of gears cost? I would think you could buy a bunch of diesel for the same costs. I dont think changing gears will justify the cost savings.

 

yea exactly. i was gunna get my set for free from a buddy but then i went to the place that i trusted to get then changed out and they guys gave me an etimate of 1800. i figured ide rather stick with the 12mpg.

 

LOL... In a stock truck it would never pencil out IMHO...

 

lol agreed. i think it would be cheaper to go on craigslist and find a pulled rear and put it in.

 

I didnt have much choice when I did mine...

 

hhahha oh wow. that is intense. what led to that?

 

Also look at the big picture and ask yourself just how many miles you will have to drive to recoup the money you spent on gears or an OD unit. How many years will that take to break even?
If you have to do gears that's one thing, but you'll probably find after you get the calculator out that a gear swap just for fuel economy isn't going to pay off.

 

Don't forget about the extra load you will be putting on the clutch.

 

I'm guessing he will say it was his DP Tuner.