I currently lifted put a 12" lift and 40" toyo m/ts on my 08 silverado 5.3l and as i thought gas mileage went to hell, but worse than i thought. I'm only getting around 7 highway. Would changing the gear ratio from 3.73 make a huge difference? Was thinking maybe 5.17. Already reprogrammed for the new tire size. Adding ramair kit did help a little, like 1mpg highway, but still not quite enough to drive everyday. Any input would be greatly appreciated

 

Yeah I would defenitely assume that a bigger gear ratio would help, but so would some pictures of that beast!!

 

Your engine is turning such low RPM's at highway speed, it's under a strain all the time. You need your truck to be working somewhere in its better torque range at highway speed.

Try this site: http://www.offroaders.com/info/tech-...ng/mph-rpm.htm

It's a simple math problem near the bottom of the page. Of course, you won't get back to the mileage you had before because of the added rolling mass of the new tires.

 

Thx for the help, apparently the 5.17 is ideal for my tire size. Looks like a have a new project this week and will be enjoying delicious ramen noodles until it's completion ;-) Will toss up pics of the finished product soon

 

Don't know what sounds better 5.17's or the roman noodles,either way let us know how they both turn out.

 

i look forward to seing this. I have not seen too many of the new body styles done up to that extent yet. good luck

 

Wow that really sucks the gas. Is that with Active Fuel Management too? I also can't wait to see the pictures of it.

 

Hope this helps

http://www.4lo.com/calc/geartable.htm

 

thx for the chart, its nearly impossible to find gears for this thing... looked everywhere and the aftermarkets places are no help... keepin at it tho... all i keep running into are replacement parts, which is complete bs... does no one change gears in this truck? decided to go with the 5.71 for power, its just finding it that's the problem. Bad news is over the weekend some dicks at my apt complex decided that throwing beer cans on my truck would be a good idea on a rainy night, so now i have rust rings all over my 3 week old hood... now i need to get it repainted and insurance wont cover b/c it's aftermarket. quote was $1175 for repaint...