Kerr

its hard to say, mileage depend on where you dive and how..

we have 6.0 in a 2500 crew cab with 4:10's but live in the mountains, if you drive normal you can 13-14 mpg in town if you lucky... On the highway you get 18 mpg at 70 but with the 4:10 gears its turning 3200 rpms.

25006.0

More like 2200rpms unless your in D instead of OD

nonnieselman

iTrader: (10)

Depends on his tire height also.. my dads 2500HD 6L/80E/4.10s has the stock 245s and his turns almost 2800 at 70.

Last time i went to texas for the Evadale GTG i think aroud 900 miles round trip and averaged 22. that includes 4 passes on the track and several city miles playin in boost

Like said, it depends on the tune and driving habits. mine leanes out to the high 15s afr while cruising. and i drive like a grandpa after the recent tickets.

iregret

iTrader: (4)

I know this tread is kind of old, but these mpg's seem almost farfetched! I have a 00' rcsb 4x4 5.3 4l60e 3.73 (I think) stock tune, cai, shorties and do mostly freeway driving. I usually get 16.2mpg.

I'm considering a swap to a 6.0 4l80e and the biggest deterrent has been mpg since this is my daily driver.

If you guys are saying it's possible to maintain similar mileage, while swapping to a bigger engine, I'm all in!

GMCtrk

iTrader: (27)

Cammed 6.0, 4l80e, stock verterand 4.10s i get 12-13 in town with moderate driving. Pure highway 75 cruise it gets 16-16.5. With the 3600 stall I got 8 mpg.

Back with the 4l60 and 3.42s, stock 6.0 i could pull down 22 highway all day long

duwem

iTrader: (1)

I'm trying to figure out if I want to hang a 60E or 80E off the back of my 6.0L LQ9.

I want a bullet proof drivetrain, but dont want to have to stop at the gas station every 200 miles to fill up.

Engine is going in a 1950 3100, so there is an advantage that it only weights 3200 ish lbs as it sits, so maybe a 60 with vette servo and shift kit would be all the durability I would need?

Is there a rough estimate as to what MPG change going from a 60 to an 80 is?

Does part of it have to do with different ratios inside causing the engine to spin different RPM at a given MPH, or is it that everything is heavier and consumes more power?

GMCtrk

iTrader: (27)

I lost about 1 mpg highway with the 4l80e.

With a truck that light I would just go with a built 4l60e and be done with it. A good one should hold up pretty well.