My new to me truck seems to do alright in town/country driving i get 16mpg but if i hit the highway with a couple dirt bikes on board at 75 which it kills me to drive that slow out here i get about 13.5... just doesn't seem right i have a 99 5.2 4x4 with 5pd i just dont get how my mileage is better in town than on highway... it has 31x10.5 15s on it and maybe the 3.55 gears... i do need to do a tune up tho and i am wondering if she's got a dead hole...

 

thats actually a little above normal for the 5.2. I have a 4.7 and I am supposed to get that kind of mileage going ***** to the wall haha

 

gears - i thought higher gears got you worse gas mileage. i have the 5.9 with the 3.92 rear and have been getting 14-15 on the highway. if i put a 4.10 on there, the mpg's would go down, no?

cargo - have you made this trip with just yourself and no passengers/cargo with the same amount of gas and compared?

oil - have you tried a good synthetic (amsoil)? motor oil actually causes friction and a synthetic reduces that. less friction = less work for the engine = less heat = more power and better gas mileage

just my two cents!

 

Yes. It's a quadratic curve. You would lose mileage going from 3.92 to 4.10 or 4.56 across the board. But your mileage would stay about the same highway with 3.55, and you'd lose some city. You'd lose everywhere with 3.23's.

In my case (V6), I have 3.55's with taller tires (effective ratio in the 3.20's). I get 18-20 MPG highway, but only around 10-12 city. If I go to 4.10's, I'll get closer to 16MPG both ways.

The reason is torque multiplication and application. With a high-torque motor (V8), you have more root torque, so you need less gear torque multiplication to get the same amount of power to the ground. For a weak motor (V6, I4), there is less root torque, so we need more gear to get it to the ground effectively.

If you have too tall of a gear, you'll bog the motor down in the city, but momentum will take over on the highway, you might lose a little bit if you do alot of passing, but cruise should go up. Too low a gear, and you're just burning gas, applying more torque than neccesary.

 

well i pulled the plugs and they weren't in the best shape nor the cap and rotor so i replaced all those and i will test the mileage again i am also waiting to hear from a guy in town with an exhaust for this thing anyone have or heard a pacesetter exhaust on a 5.2? it has dual tips that exit where the single factory did...

 

I just did a city run. 217 miles on 17.1 gallons of gas. 12.69 MPG