Has anyone figured out how to get better fuel milage out of the 2003 4.7? I have an Air raid cold air intake, throttle body spacer, flow master muffler, and a programmer set on 87 octane. Is a Hemi swap possible?

 

as your first post..... i will say that question has been asked 100 times monday and prob 200 times today.....use the FAQ sec on the top of this page . also try a search. you are not going to get answers to this kind of question because we are all sick of responding to the same one over and over....so look in the FAQ and or do a search
welcom to DF

 

Well put my brother! FAQ and SEARCH! Nuff said

 

well the first thing you can do is get rid of that useless throttlebody spacer.if anything it'll make your mpg worse.I have a '05 4.7 and i put the airraid m.i.t with a drop in k&N filter,got a tuner and put in a e-fan.There is very significant difference in power and mpg.I haven't ran the numbers yet since i'm still on the first tank of gas since the e-fan install,But i can tell it made a difference.And i can sure smoke thoose 20's no problem now

 

Some say flowmaster mufflers killed their low end. After seeing the inside of a flowmaster muffler they are not designed for flow mostly sound. Even if you switch that out you wont see a significant increase in mpg, probably gain back the little you lost if you did feel you lost low end power when you swaped mufflers.

In reality nothing well give you better mpg to justify the cost you are going to spend for the little mpg you will gain. My biggest was upgrading my gear ratio which I gained about 1.5-2 mpg depending on how I drive. If you have the 3.55 gear ratio you are going to benefit from an upgraded gear ratio and is the best upgrade you can do to our trucks.

An efan will help some since your motor well be working less.

Other than that keep up with the vehicle mainteance and tires inflated to proper psi level.

Forget about the 5.7 swap if you are only looking for mileage gain. The swap can happen, but spending about 2500-3k in parts only, will not be worth the 1-2mpg gain.

 

Ive seen dyno numbers, and some will agree, the flowmaster actually robs you of the power. But you already have it installed, so no biggy.

Re-gear. re-gear, re-gear. this is your best bet. Until then, drive accordingly. When you take off, graduate accelerate to 2000 RPM, hold until it shifts, and follow through the gears. Ive found that by driving with my tow/haul on, i get better fuel mileage too. Even on the freeway at 75..