Originally Posted by cttandy

Something to really think about.

Do you want a toy or do you want good gas mileage?

Not saying you can't do both, but there is something big many people overlook. If you have spent or are spending money to get better mileage, how long will it take you to get your investment back. I sat down and did a cost analysis on my fuel mileage build. With very careful planning and doing a lot of horse trading, I will see a return on my investment by the end of summer. As of now, I have $450 invested in my search for fuel mileage, with my current gains and typical driving, I should save around $800 a year at the pump.

Buying a new vehicle to save fuel, then spending more every month on a payment for the vehicle then what you saved in fuel doesn't add up. Even if you paid cash, how long will it take you to see a return in fuel mileage? 6-10 years maybe, will you still have the truck then? If that is the case, spend the $2,000 on a old honda and park the new truck for the weekends with the family.

If you are building a toy, or wanted a nicer more family friendly truck, then the real concern is, I want to add power but still maintain decent mileage. With that said, less would be more.
Small cam that doesn't need a convertor.
I am a fan of a good built transmission with 3.42 or 3.08 gears. (my pickups was built for pulling, but the lack of gear hunting since the build improved the mileage from 17 to 20MPG, when it was on stock tires)
A good intake and exhaust to compliment the tune. I saw nearly a 5MPG gain in dumping my flowmaster in favor of a better muffler. We saw the mileage go south when we put the flowmaster on, so I don't think it was a gain over stock, just a gain over flowmaster. I think I would leave the cats on or replace them with some good aftermarket cats. My experience with mileage has been better with cats then without cats.
LS motors don't seem to like being lugged, for some reason optimal mileage seems to be had around 2200RPM. If you gearing or tires isn't getting you near that, it might be something for you to consider. My old TBI motors on the other hand, like to darn near idle on the interstate and sip on fuel.
If you can get non-ethanol gas, you will see a gain over the ethanol mix. My Dad's little van jumped 4 MPG just filling up with non-ethanol. I don't know what my old truck gained as the speedo hasn't been accurate in a few years, but my fill ups took me about a week further then before (36 gallon fill-ups though). Everything else I have, has only had non-ethanol since I got it including my mower.

I am half asleep so if any of this doesn't make since, I am very sorry.

Originally Posted by dlt76028

I say put a good tune in it and leave it as stock as possible for the best mpg. Mine has 3.42s also, and 110lb 33" tires, and I get 14mpg 100% city, and it moves out just fine. On the highway I'm sure it would get 17-18, but at 70 I'm at 1700rpms, so it does unlock or downshift on inclines. It just depends where you do most of your driving.

Originally Posted by nonnieselman

I have the ISKY 215/215 .566''/.566'' 114*+2 in my stock LQ4 and with the 4L80e 3.42s and 265/65/17s it has no problem pulling a hill in OD with the converter locked even with 1200# of welding stuff in the bed. im at 2050rpms doin 70.
I havent gone on a long trip in quite some time but ive been averaging 15mpg most of that is goin 45mph on the backroads and the converter doesnt lock till 55.


The vacuum gauge is a really good idea, or if your use to tuning Speed Density and watching the VE talbe, you know the slow transitions help mileage.

Originally Posted by SimpleManLance

thanks for the post andy. im looking for a family friendly truck that i can take on a trip and get decent gas mileage. yet i still want quick truck. im looking for something tame that will make the best out of what im working with. im not to concerned with getting a return on my investment with gas savings. more of just not having to add another $100 to a vacation because my truck gets crappy MPG and i have to fill up an extra time. my main area i want to maintain my MPG is on the highway/interstate. thats why i think something that has got the power to keep the truck cruising at 70-80mph would be beneficial.

im really leaning towards a cammed 6L with 243 heads. something that has has power from idle to 6000 rpms.

Originally Posted by SimpleManLance

im really leaning towards a cammed 6L with 243 heads. something that has has power from idle to 6000 rpms.