Hi everybody, I need help with a decision here. I recently picked up some used 3.92s from a 3rd gen member on here (same 9.25 axle as us), and am about to install them. I am going to have the work done at my fathers shop, and everyone up there keeps telling me that I will have a severe drop in mileage with my setup. Obviously, I realize there is going to be some highway mileage lost, but I wouldn't think it is as much as they are making it out to be. My tires right now are 30" exactly, I would think around 2000 RPM I would be around 67mph or so according to many of the gearing calculators out on the net.

My question is, should I go through with it? I will be traveling back and forth about 50 miles twice a week. So that equates to about 200 miles a week plus the miles between my apartment and college. Either way, I am still looking for a nice power increase, would the Roller Rockers be a better choice since there is really no drop in mileage as long as I keep my foot out of it on the interstate? Right now I am getting around 19.5 almost 20mpg on the highway at 70mph exactly, which I am very happy with so I don't feel like buying a beater compact econo car. So all of this basically leads to the question, go ahead with the 3.92 installation or sell the gears and just go with some Roller Rockers.

Any advice/insight is much appreciated!

 

well the 1.7 opens the valve more, so in a way more gas, i asked if anybody knew if there mpg when down, no one had a really answer, maybe you will

u know my mpg story

 

If I was getting 20 mpg, all I would do is put gas in it once in a while, and leave the rest alone.

 

your going to need a new carrier for the new gears.. i say do 4.10s going from 3.55 too 3.92 prob isnt much of a diffrence . i dunno see what else people say .

 

It's when you go beyond 3.92 that you need new carriers.

 

Thick gears take care of that problem.

 

Thanks everyone


lastrights....your not taking mileage into account. And as unregistered said, you don't need a new carrier.

 

he is 2wd guys, no need for carrier, I say gears......I say it will all depend on the motor and its sweet spot as far as the mileage cant see you losing more than 2mpgs at the most.

 

Right on, thank you.

 

Both mods will hurt mileage.

If you got the gears and the labors cheap, put them in.