Mr. Sandog

I have 12 more months on my TBSS lease and am thinking about what I want to do next. The reason I did a lease was so I would simply leave the vehicle alone. The plan has worked out great. I don't even have a tune, it is 100% stock. But, by the time the lease is up, I'll be ready to play again.

What I liked about my Avalanche (5800 lbs) when I first put the Radix on was the 19.7 MPG on the freeway. Boy do I miss those days. Now, if I get 13 MPG in the TBSS (4600 lbs), I'm stoked. Let's just say that that never happens. And I'm not a lead foot by a long shot, I'm a pretty sedate driver.

Displacement is the main issue, it appears. The Silverado SS guys never talk about mileage because there's just nothing good to talk about there. So it seems that six liters is just piggy, whether you're talking LQ4, LQ9, or LS2. All that displacement just eats the gas.

So back to my idea. I am thinking about getting a 2004-2006 Tahoe with the 5.3L (same motor I had in my AV), putting in some forged internals, slapping on the best roots/screw blower at the time (Kenne Bell 2.8L? Magnuson TVS? MP122? Whipple 3.3L?), and running with it.

Option 2 is to bore the stock iron block out to 5.7L and make a stout, 350ci, iron-block, forged motor to receive the aforementioned blower. What I don't know is what that extra 25ci will do for me, if anything. Whether my goals would just be better served sticking with the 5.3L, 325ci stock block.

Some people like to go Mach 2 with their hair on fire, some people like to street race...my obsession is to have a quiet, daily driver SUV that has perfect street manners and gets great mileage, but when you stomp on it, all hell breaks loose.

Any comments, ideas or input?

jblack6527

I like it either way you go.

tdrumm

iTrader: (18)

I like the forged iron block 5.7, but do you think it would be substantially better on gas than a 6.0?

BADMOFO

Check with Whitt1 for his input. I think he's done what you're talking about or something close....before he swapped in the 402.

Quik

iTrader: (7)

with my old setup i seen 18mpg on highway trip, its all in the tune

Shea

I agree with this for the most part. Also, most vehicles get worse and worse gas mileage the more work you do to them. You have to increase the amount of fuel you deliver with mods, therefore worse gas mileage.

If you want the best gas mileage for the most amount of hp, then forced induction is your best bet, atleast, IMO of course.

Quik

iTrader: (7)

i ran a 3800 stall, 410s, was on chrome 20s, i ran svo 30s, the TSP TV2 cam with a 11.1 6.0 with leather interior and a stereo thats what i got. i made the motor lean off the highway which helped out greatly. in city i seen average 13mpg

so yes a tune will greatly do it. before the lean mode tune i seen 13 on highway. then leaned the truck out greatly when not in PE and crusing and thats what netted teh MPG increase, i also cleaned my K&N lol

LesPaul

agreed

my setup gets me 17 mpg on the highway... that's with a bit of a lead foot too....... the reason the 6.0 guys never talk about millage because we are too busy talking about how our truck hauls *** btw i like the 5.7 idea

onebadrubi

You aint jokin, that can net you 1-2mpg. HAHA yah i let mine get that dirty one time.

dropkick13

how do you lean out ONLY highway driving? I am going to be doing a mail order tune soon and i want to know what to tell him cuz i like your idea of being able to mash the gas and get all the fuel you want but when just cruising its lean...didnt know it was possible