So what is it about the 6.0 that they always get crap fuel mileage? I've had 5.3 and 5.7 return over 20 miles to the gallon on a regular basis but I've never had a 6.0 get better than 14. I have an ly6 that I am hesitant to use because it will go in a daily driver.

 

My 6.0's got better than 14 in a 4x4 truck but not by much. 17 in town average and 19 hwy. My S10 is running an LY6 with LSA supercharger and manual 6-speed, It get better mileage but I can't say how much better because I usually drive it a lot harder all the time. You're not going to get great gas mileage from a 6.0 if it's in a heavy vehicle with an automatic unless your drive like an old woman.

 

6.0L is usually married to a 4L80E transmission. That's a lot of the reason right there. Usually in a heavier vehicle. And those vehicles tend to have the heaviest wheel and tire packages. And some of the 6.0L engine tunes flat out suck.

 

Truck 6.0s have low compression and very conservative ignition timing to prevent pinging under the higher loads they encounter in the 3/4 and 1 ton trucks they are in.
That plus the low-geared rear ends and aforementioned heavy trannies.
There is no such thing as a 3/4-1 ton truck getting very good fuel mileage.
It's not so much the engine but the vehicle it's pushing around.

 

Interesting, I'd be going in my 02 S10 xtreme. It would be backed by a T56 and most likely my current 3.42 8.5 10 bolt.

 

Theres a thread here discussing this exact topic. Goes on for days....

https://ls1tech.com/forums/generatio...o-thirsty.html

 

Thought you forgot about that thread.... so many opinions and reasons why.

 

Thank you.

 

That was a cool thread surprised how many people wondered the same thing

 

Drove to Lake Tahoe & back, 430 miles, 1 tank 15.5 gallons 70-75 mph mostly. 27.4 mpg in a 07 C6 M6.
Wt, aero drag, gears,trans,driving style,compression, stroke and cam are all bigger factors than bore size for mileage between 5.3. 5.7,6.0, even 6.2 (with cathedral heads).
A 6.0 built right with a t56 & 3.42-3.90s in a s10 should have similar mpg to 5.7 or 5.3, maybe better.

 

Even if you took an LM7 out of a 1/2 ton pickup that got about 18-19 on the road, put in a 3/4 ton ahead of a 4L80E and BIG rear end with 3.73 gears, mileage would plummet. Much more drag,

 

I havent run an LY6 yet but numerous L92's and they get substantially better hwy mileage than old cable 5.3's, never mind the 6.0L. As that thread goes in detail, the 6.0L is low compression, heavy trans, heavy wheels, low gears, high riding ( less aero ) heavier chassis etc etc etc. In light cars with a 243 head the 6.0L is great on fuel if set up and tuned properly, although not as good as the 6.2's are in my experience anyways. Those engines ( very similar to the LY6 ) run well and I wouldn't hesitate to run one as a daily

 

After reading all 34 pages of that thread over several days, I've come to the conclusion that in my s10 with a t56 and my 3.42 gears it won't kill me if I make the following changes. Compression; the LS2 and LS3 have 10.9 and 10.7 for their ratio. I need to be there. Cam; I need an appropriate cam - I'm not going for power but driveability and 2 more cylinders will do that. Electric fans; I was planning on that anyway. A legitimate tune; a canned "power" tune isn't going to suit my goals. Realistically my setup isn't far from an LS2 powered GTO, the weight, gearing, transmission and tire size are almost identical.
Now I have to find the right pistons and cam.

 

That sounds like a cool build

 

I like the little truck.

 

A 6.0L With 243 head, stock valves are fine, decent beehive from PAC or PSi 1511ml and a straight grind like a TSP228r or even the Thunder TR224 112 with a four bolt genIV stock truck intake will be a great driver! Tuned to run on 91 pump and it will make great power, a lot more than a stock LS2 and get excellent hwy mileage. Town mileage will be more about your foot than the engine and its hard not to lay into these torquey combos. Nice and simple and loads of fun. The real key is getting the tune dialed in after all your mods and build is done you want to really get the tune up dialed it makes all the difference. Often little things like running stock 20 year old injectors are overlooked and people blame the tune or the parts are poorly matched and people blame the tune or they are not put together well and people blame the tune. You see where Im going here....

As a general rule duration numbers up to 225 degrees make great daily driver cams and once you start to crest 230 degress your entering race cam territory. Its not that you cant drive those big sticks around on the street quite comforatbly its the valve train pounding and short shelf life of the valve springs that limits their real street worthyness. So the real issue is deciding how much turn key and go reliability you want to sacrifice to make more power and really on the street how much does it matter? Sure a split 235/245 range cam on a 6.0L with notched pistons and ported shaved heads running C25 will be absolutely KILLER! its not going to make double the hp of the TR224 or TSP228r ( two verrrrrrry fun fast cams on 5.7-6.0 engines respectively ) the radical set up may make 50-75 hp more, AFTER 6000 RPM but up til there? Not going to be much difference and below 4000 RPM the smaller cams are going to pull harder.

I could go on and on i often do but time is tight so if it were my money and my truck and I was street driving it for fun id do the combo i listed; 6.0L 243 head, LS6 Mahle MLS head gaskets, TSP228r, PSI1511ml springs, stock retainers and valves, new valve seals, new LS7 lifters * real Delco not aftermarket they are poop imo * or morel high lift but I like delco, chromo pusherods with 80 thou preload, 1 3/4" long tubes, dual 3" or single 3.5"/4" exh, Four bolt gen IV truck intake or LS6 3 bolt, Fleaby 4 bolt 90mm TB or ported stock LS1 three bolt, ( maybe holley snyper if funds permit ) brand new injectors ( 40lb or so plenty enough ) new Walboro 255, Corvette fuel filter, LS7 MAF card on a 4" clean intake system. Trans either a t56, 4L60, or 4L80. Spend the money on a GOOD quality stall and if 4L60 use the Borg clutches and do the boost valves, vette servo, and new solenoids. 3.73 final gear ratio and HANG ON its gonna rock

I think that about covers it.

 

I definitely want to stick to the square port 823 heads. This is a daily driver so longevity and mpg is more important than power. The stock power level would be fine, the truck weighs 3700 pounds with a full tank of fuel and me in it so it will make more than 1 horsepower and foot pound for every 10 pounds. I just need a cam to ditch vvt. I would like to find long tubes to fit but 99 fbody manifolds would be fine as well.

 

Hmmm tricky combo. Without good long tubes your seriously limiting the cams ability to make power. Most of the gains in cam swaps are in the higher RPM ranges which is right where manifolds choke so its a peter/paul situation. If you wanted to stick with a grunt type cam you will get really good mileage and still have a crispy combo. For a serious DD cam to take things one step further you could drop the lift below 560 and use the stock LS3 springs which work very well and last a very long time and basically your engine would be as reliable as new OEM. Even the cams I chose above will still require fairly frequent valve spring replacements. For a true DD Cam Motion has some great grinds available in relatively mild lobes that will still make good power and peak before the manifolds really choke it out. The 6.2L Stage one high lift with LS3 springs would be good ( call them to see if that spring is enough ) or better yet see if they have a grind specifically for the 6.0L with the square port head. The square port head is awesome and makes great power but its awfully big for the smaller bore of the 6.0L and the intake valve gets shrowded up making cam selection a tricky process. Its easy to go too big with those hence my favoring cathedrals on 4" bore or less because its easy to pick really fun, fast cam combos. With the square ports on the smaller bores unless your willing to rev to the moon its not as easy but it is still doable. Its the manifolds that limit you here so if you err on slightly smaller the combo will work a lot better that even slightly too big. Best of all with these smaller grinds you dont need to spend coin on a converter the stocker is perfect. What trans are you planning to use?

As for the supporting components stock LY6/L92 intake is a good choice, LS3 probably slightly better or again theres the Holley fabricated units that also work well. Stock 87mm truck TB works just as well as the LS3 90 but i do suggest porting it. The 87mm tb's have a huge ramped lip in the throat that when taken out makes throttle response sooooo nice its a very nec mod imo. Hope this is of some help

 

Mileage, come on. 6.0's should be built for max power and blown up as necessary, Rebuild and keep going. 4.8's and 5.3's are for mileage if you need a daily driver.

 

I came home from lake Tahoe to Salinas ca got 29.2 it was a bone stock 2006 MN6 LS2 corvette, even hot rodded now it gets 24 if I keep my foot out of it