Sanster

i have a 08 silverado 4.8 reg cab long box 4x4 with 3:42 gears in it i put a magnaflow muffler a K&N drop in filter and a diablosport tuner and running factory 265/70R17 tires still only pulling 13-14 mpg no matter what i do. im usually city driving with 8 mile high way ride to work. Im wondering if swapping to a 3:73 would help my mileage out since it seems like i have to always give it so much throttle just to enter the highway/merge/take off at lights. What do you guys think?

Mangled03gmc

iTrader: (95)

you will prob pick up a few MPG with the 73's in that truck.

Sanster

Kinda what i thought to since the thing is a complete slug on the road. It ran really good in the dunes the other weekend in 4low but you could still tell the gear ratio was really hurting it.

chriscon7

regearing costs way to much to go from 3.42's to only 3.73's. the benefit doesn't outweigh the cost at all. Especially since yours is 4x4, you'd have to do the front and rear. If you were going to regear, i'd say at the very least step up to 4.10's

Sanster

im not worried about the cost my uncle owns a trans shop. i just have to pay for the gears and with the 265's im thinking the 4:10 would be way to low.

mvrk10256

Well higher numerical gears (4.10 being high than 3.73) is going to make you engine RPM go up. Generally when engine RPM goes up so does fuel consumption. usually people go to a numerical lower (although often refered to as a "taller" gear).

chriscon7

Tradiationally yes. However, it sounds like OP does more city driving than highway (8 or so miles a day he said). Therefore he might see a slight decrease in mileage in the short time he's on the highway but in the city it will be better.

And about the cost, relatively it is still costly to do a gear swap. Eventhough you may not have to pay for labor cause of your uncles shop, the cost of new gears front/rear and both install kits will run you between 400 and 600 bucks.

rjwz28

It will take quite a while to recoup your cost on fuel savings if that is your only motivation for the swap. If you are looking for more torque and a more drivable setup with your gear swap, I would most certainly swap to 4.10s and skip 3.73s altogether. Don't fear the gear.

Robert91RS

iTrader: (2)

Tune and headers would stand a better chance of improving mpg.

CodyG

Don't buy a truck of your worried about MPG....Just sayin what everyone's thinking....But gears will help some its not gonna mater because you might see 1-2mpg, so why do it!?