86 replies to this topic

[ptmeyer84]

Post your truck's model, gearing, performance upgrades and relative city/highway percentage. I would like to see just how much worse the gas mileage is compared to a 6.0L. Thanks

[moo snutz]

Hey ptmeyer84 - I get between 11 and 12 average with a daily commute of 30 miles (40/60 city/hwy). I've got 4:10s and 265/75s. On pure highway trips, I get close to 13.5 - not too bad at all. I just put on a TrueFlow air intake and didn't notice an increase in my daily average - probably because I get on it a little more now BUT I just got back from a 550 mile rnd trip camping trip down into the Navajo Nation in AZ with a 2500lb slide-in camper & got 11.5mpg !!! I normally got 8-9 with the camper. BTW - I live at 7000ft.

Take it easy & welcome

[DSengineer]

I thought the 8.1 only came with 3.73 rear end. Are 4.10's an option?

[Daubs]

Good poll.

I'm driving 04 CC 2500HD with Big Block / Allison combo. Have 3.73 gears and 285 REVO's. Started off in the 8.5-9 MPG range around town and 10-11 MPG highway.

Changed intake to Volant cold air system. Got Westers tune and asked him to change spedo for tires and give me good MPG. Now I'm avaraging around 11-11.5 MPG city. And getting 13-14 MPG Highway.

Only complaint I have is my engine has developed the cold start knock. Aside from that I'm very pleased with the Big Block. Loads of power and pretty darn good MPG for a 496 cid engine!

[ABQFirefighter]

4.10's are an option and I have them. Also, 295/75R16 tires, 4" lift and I get between 9-10 in town. Towing the 5'er, 6-7mpg.

[dewfpo]

12.02 mpg average since new (hand calculated not DIC, DIC reads high), 95% rural, no city, 5% highway. High Altitude.
Bone Stock 8.1L 4x4 with 4.10's

If I reset the DIC while on the highway and set the cruise at 65 mph I can break 14 mpg.

DEWFPO

Edited by dewfpo, 11 July 2006 - 02:10 PM.

[dewfpo]

I thought the 8.1 only came with 3.73 rear end.  Are 4.10's an option?

<{POST_SNAPBACK}>

Your thinking of the Duramax.

DEWFPO

[Wirenut]

4.10's are an option and I have them. Also, 295/75R16 tires, 4" lift and I get between 9-10 in town. Towing the 5'er, 6-7mpg.

<{POST_SNAPBACK}>

4" Lift and 295s I would have thought your 5er rear bumper would be draggin' on the ground Nice scenery in the background (PICTURE)



2001, 3500, 285s, 4.10 I get a tiny bit better than 11mpg on the highway.
7mpg towing my 11,400 fifth wheel.

[Cheekster96]

2006 2500HD with the 4.10s. regular cab and 4x4.
Got the six speed ally with it, awesome! Double overdrive gear is nice with the big block.
I am not much in a hurry when travelling out on the turnpike..generally do 65-70 mph. I dont have the steering control buttons so i dont know the instant fuel mileage but after a fill up, i generally average 11.5-11.9 mpg. I dont tow. Truck just turned 2500 miles.
Everything is stock.
I did have to replace a tail light because it burnt out and that was about 200 miles ago.
Later
Lee

[rlarson]

11.5-12 for me on my regular daily comute 80/20 highway/city with an 04 3.73 gears and 265/75's only mod being westers pcm which made no noticable change in mpg (which was my biggest reason for spending over $500)

[Trouttrooper]

11-12 mpg empty
10-11 mpg loaded

4:10's Allison, crew cab, long box, 3500SRW


My old truck....1999 GMC 2500LD 6.0, 4:10's, extended cab, long box

15 mpg empty
6-7 mpg loaded


Since my truck most often is towing or hauling a load it actually makes economic sense to own the bigger engine. My yearly average mpg is better with the 8.1 then when I had the 6.0

[linda]

Post your truck's model, gearing, performance upgrades and relative city/highway percentage.  I would like to see just how much worse the gas mileage is compared to a 6.0L.  Thanks

<{POST_SNAPBACK}>

2003 ECSB 4x4 Allison trany
whipple supercharger @6psi
Dmax intercooler
4.10 rear / G80

I have no idea what i get for gas milage and i love it. Its gotta be single digits because i find my shoe getting stuck to the floor with the gas pedal underneath it everytime i go out on the road. Its like my foot is made out of lead or something...LOL

[Shooter_va]

I get between 10 and 11 average around the area I live, 12 to 13 Hwy and 8 to 9 towing my 10k lbs 5er. I've got 3:73s and 265/75s on my 2001.

[Bart2500HD]

I get between 10 and 11 average around the area I live, 12 to 13 Hwy and 8 to 9 towing my 10k lbs 5er. I've got 3:73s and 265/75s on my 2001.

<{POST_SNAPBACK}>

Shooter,

How fast do you drive pulling your 5er? My 5er is about the same size and our trucks are basically the same, except I have an extended cab and 4.10's in it. I usually pull at about 65mph with the tow mode on and never get higher than 8mpg towing. Of course where I tow there are hills and I usually have to fight the wind too.

[dco111]

I have a 03 3500 crew cab with duals. Before the wait 4 me I got 5-6 pulling 9-10 empty, after 8-9 pulling and 12-13 empty. I have a 28' fifth wheel weighing around 12000. I run anywhere from 65-80. LOVE that tune.