Ok so i picked up a new to me 06 GMC Sierra Z71 4x4 5.3.. Truck needs a few maintenance items taken care of.. but it has a LOT of miles on it..

180K+

All highway, dealer service every 4500...

Anyway, i want to start slowly putting things together for the inevitable, im sure the engine will give me issues at some point.. and i want a game plan..

I like the truck getting 20mpg, i also like the way it rides and handles and the space.. It could use a bit more powa tho.

I have a 5.3 on a stand in the garage, i can either build that or go to a JY and get a 6.0

Question is what kind of mileage are you all getting in a similar truck with a mildly built 6.0 or a mild 5.3

Im talking good pistons, good heads, TBSS intake, Smaller cam, Headers.. Tune..

I want something about 10.5:1 and about a 220 cam..

Still want some sort of decent mileage...

Chime in with what you are all getting..

 

Oh yeah, almost forgot the pics..

 

nice truck, but I always laugh when they say "all highway miles" it's not even possible.... BTW a mild 6.0 with the right gears and stock converter will get just as good of mpg as a stock 5.3

 

It really is all highway miles.. Guy lived in indy and drove to north indiana for work every day.. Interior says same story, seats and all look like new..

It was def a get-in-- sit down-- drive to location -- get out -- repeat -- and do it over the next day..

At any rate now that i have attempted to clean up the engine a little bit i find that it is the aluminum block 5.3..

Perhaps i should just keep this one and give it a refreshing..

Or find an LS2...

 

I agree it is usually used as a BS sales "confidants booster" but the CEO of the company I work for puts nearly all highway miles on. His house is in Akron Ohio and the shop is about 2.5 hours away. He drives home 2-4 times a week and stays in town most of the week. Literally about 99% of his miles are spent on the Ohio turnpike.

20 mpg is good and I don't foresee a built 6.0 getting that. In my 01 2500 with a stock 230,000 mile 6.0 I got 17 on the highway. Now if you get a perfect set up with a perfect gears and light weight wheels and tires, 20 mpg isn't completely out of the questing.

 

sweet man, an l33 is a great engine. put a tune and some bolt ons and see if thats enough for you.

 

I recently replaced my high mileage 5.3 with a lq4 and comp 265 low lift cam. My mods are ( besides 6.0 and comp 265 ) only electric fans a cone air filter (stock tube) BB tune and a summit muffler. I still have the factory 3.42s, coverter, manifolds, and cats. The power difference is amazing its a totally different truck. I recently took the truck on a 950 mile road trip for work and had the bed full of luggage and household stuff and I really cant tell the difference in the mileage full of stuff with the 6.0 and when I had way less stuff on a simular trip with the 5.3.

 

I disagree. A 2500 weighs a ton more than a 1500. If you got 17 on the highway in your truck then a lighter truck with the same setup shouldn't have too much trouble getting 20mpg. I would think even a mildly modified 6.0 in a moderate 1500 would get the 17 highway mpg you saw in your 2500. Just my $.02.

 

I agree high teens are possible. If you nail the set you and match the cam, heads and tune along with the right gear for the set up you might be able to hit 20 mpgs.

 

If i put a set of 16s or 17s on my truck I could squeeze 20mpg out of it. But the bigger cams and stalls i believe are the main killers