How can I increase my 2002 Tahoe 4WD LT's Fuel Economy???

[xFuZzYx]

So at the moment I drive a 2002 4WD Tahoe LT with 234k-ish miles on it. My current modifications list that could have some kind of impact on my fuel economy includes:
- 6" Rough Country suspension lift.
- 20x14 XD Riot wheels with 35/12.50r20 Federal M/T Tires.
- 2.5" straight pipe cat back exhaust (stock cats, I just replaced my muffler with a Y-pipe to 2 4"x18" Exhaust tips.
- I also have like 600+ lbs of Audio equipment in the back of my truck.

I just recently had my spark plugs and spark plug wires replaces less than 2k miles ago and even after that I average 9 mpg around town and 11.5 mpg on the highway. What are some modifications that I could make to my truck to help increase my fuel economy as i travel the country going to professional car audio competitions. I'm open to any suggestions as long as they are not, "take out the extra weight from the audio equipment" or "get rid of your M/T's for street tires" or "put on smaller wheels/tires" or "take out your lift kit" and etc...

Here is a couple of pics just for reference. The 3rd pic is before the new exhaust work was done.

 

[sumo]

Easy throttle from stops, keep highway speeds to 65. Being lifted you have a higher resistance so your going to have to curb those rpms.

 

[drakon543]

Thats alot of rubber your turning. I didnt notice in your mods that you had your truck regeared. If you haven't had the rear regeared with 35s id have 4.56 put in to help lower your rpms as sumo mentioned.

 

[treehan77]

seems obvious, but you didn't mention: have you changed the air filter. clean throttle body? change to electric fans.

 

[SLCHOE]

Buy a second car. A Prius like I did. Drive the truck when you want to. Drive the ecobox to work and back every day.

I'm on 35's with a 6" lift and no audio gear and get maybe 11 mpg and 9 city. I love my truck but it's not economical by any means.

 

[xFuZzYx]

Easy throttle from stops, keep highway speeds to 65. Being lifted you have a higher resistance so your going to have to curb those rpms.

I generally dont go over 2.5k rpms unless im passing someone or im taking off from a dead stop with a hurry, otherwise I take my time when I drive.

Thats alot of rubber your turning. I didnt notice in your mods that you had your truck regeared. If you haven't had the rear regeared with 35s id have 4.56 put in to help lower your rpms as sumo mentioned.

What are the stock gears? and is 4.56 the best option to change to? How much power would I loose and what sort of fuel economy would I gain from switching to that gearing? Some shows require me to drive through the mountains and I don't want to sacrifice too much power for only a minimal fuel economy gain. Lastly, how much would doing this cost start to finish?

seems obvious, but you didn't mention: have you changed the air filter. clean throttle body? change to electric fans.

I planned on installing a K&N CAI here shortly but I didnt know how much power and/or fuel economy I would increase, I wanted to make sure it would be worth the money. and how much of a change would switching to electric fans make? how much do they cost to buy them and have them installed start to finish?

Buy a second car. A Prius like I did. Drive the truck when you want to. Drive the ecobox to work and back every day.

I'm on 35's with a 6" lift and no audio gear and get maybe 11 mpg and 9 city. I love my truck but it's not economical by any means.

Trust me, I have another Tahoe thats a 2004 4WD LT and a 1993 single cab 2WD toyota pickup. The Toyota pickup is my daily driver when i need some better fuel economy, but sense I still drive my tahoe all over the country for the car audio competitions I need to do everything I can to make these trips not take up as much gas lol.

 

[drakon543]

Going to a 4:56 will actually give you some of the power back you might not have even noticed you lost. I think someone posted the chart on a different thread. Its 2:30 am so im not going to look for it right now. Stock i think is 3.53 or 3.73 for you with a stock tire size of 245 75 and your essentially running a 305 or in metric you went from a 29 to a 35 in. You should increase your gearing and it will help your engine spin those tires easier so its not working so hard.

 

[xFuZzYx]

Going to a 4:56 will actually give you some of the power back you might not have even noticed you lost. I think someone posted the chart on a different thread. Its 2:30 am so im not going to look for it right now. Stock i think is 3.53 or 3.73 for you with a stock tire size of 245 75 and your essentially running a 305 or in metric you went from a 29 to a 35 in. You should increase your gearing and it will help your engine spin those tires easier so its not working so hard.

So going to 4.56 gears will increase the power and the fuel economy at the same time???

 

[drakon543]

If i can find the chart today ill post it up for you. If your truck still has the stock gears in it the engine has to work harder to maintain the same speeds as it would with the stock tire size. Which in turn will cause the engine to burn more fuel. If i can find the chart or if someone else has it and will post it there is an optimal gearing for what tire size. Go too high and you will gain only power go to low and the engine has to work harder.

 

[mizzouguy]

Gears will make the most dramatic difference, e-fans will help a little but its a lot of work and money for minimal gain. Unless your fan clutch is bad i would not bother. When I had a k&n intake i didnt notice any difference in mpg, it just looked cool and didnt require me to be buying new filters ever again. New O2 sensors with that kind of mileage will likely help, i can't believe they made it that long. Is the converter getting clogged? Other than running some fuel system cleaner through and going light on the pedal im out of ideas.