Iron Vs. Aluminum Heads

[twiget]

I don't think you'll get anywhere NEAR 20MPG. I hate to be negative, without going hybrid or diesel, it ain't happening. If it was possible, GM would have done it.

I think GM could have gotten better MPG out of big trucks. The down side would have been that the trucks would have cost a lot more.

The best things you could do for mileage on a burb are:

-get an overdrive transmission with lockup torque converter (or manual with overdrive gearing)

-get tall skinny tires

-get tall (numerically low) gears

-keep your truck stock height or even lower it

-get a 2WD

-get a diesel

I've looked into swapping in a 4L85E. Other than the serious $$$ for the tranny itself, there would be a fair amount of work involved. The tranny is a different length than the TH400, so that means a resized drive shaft, and probably relocating the tranny cross member.

I already swapped out the 4.10's, and put in a set of 3.42's. That got me an extra 3mpg alone.

I have considered taller tires, and lowering the truck, but they are kind of mutually exclusive. I think I'll probably lower it an inch or two, and keep the stock size tires.

I think the weights savings with aluminum heads on a truck is a moot point, It's not going to help much to save 40 pounds when you weight 5500.

I think what would be ideal is saving for a ls1

I am definately contemplating an LS series motor. They are expensive though, so that is probably a few years down the road. I wonder how well a super charged LSA would work in a tow rig?

Seriously though, Some engine mods are next, thus the question about iron vs. aluminum.

 

[dyeager535]

I think GM could have gotten better MPG out of big trucks. The down side would have been that the trucks would have cost a lot more.

GM isn't the only one, no new full-size gas truck I'm aware of gets "good" mileage. Mileage would sell if it COULD be coupled with power, and of course as you mention, if it were cost effective. Remember, GM is mandated to meet CAFE standards, so better mileage ANYWHERE in the brand helps, even if it does cost.

The LS series motors are far and away better than earlier. I can't comment on how they tow, but I expect the 6L motors are fairly impressive. If I were starting from "scratch" I think I'd look that direction than building a previous generation motor.