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8.1L Gas Mileage


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Poll: What is your average gas mileage with a 8.1L?

What is your average gas mileage with a 8.1L?

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#1 ptmeyer84

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Posted 11 July 2006 - 12:21 PM

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
Current Ride:
1994 Jeep Cherokee Sport 4.0L, K&N filter, 130000 miles
Future Ride:
???

#2 moo snutz

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Posted 11 July 2006 - 12:34 PM

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 :confused: 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 :crazy:

#3 DSengineer

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Posted 11 July 2006 - 01:26 PM

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

#4 Daubs

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Posted 11 July 2006 - 01:30 PM

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!
2004 2500HD 4x4 Crew Cab 8.1/Allison
2007 Yukon XL Denali (Wife's ride)
1972 K-20 4x4 350/4 spd.

#5 ABQFirefighter

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Posted 11 July 2006 - 01:58 PM

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.
New - 2007.5 Silverado 2500HD, 4WD, LMM, CCSB, LT1. Quadzilla Stealth 2 on the 110hp setting, MBRP 4" downpipe back exhaust, Cognito upper control arms, green keys, Bilstein 5100's, Nitto Terra Grappler 285/75's, AirLift helper bags and of course, the air horn!

Old - 2001 2500HD 4x4 / 8.1 / ALLISON

Tows:
My 2004 Prowler 5'er
My Rides:
My Current HD
1990 Chevy Truck (Sport Truck Cover)
1996 Dually

#6 dewfpo

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Posted 11 July 2006 - 02:05 PM

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. :rant:

DEWFPO

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

2005 Silverado 2500HD, CC SB, 4x4, 8.1L/Allison, 4.10's, Locker, Dual Batteries, 145 Amp alt., Bilsteins
Retrax Rolling Tonneau, Putco SS/Chrome Side Rails, Bushwacker Bed Rail Protectors,Husky Floor Liners

#7 dewfpo

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Posted 11 July 2006 - 02:10 PM

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
2005 Silverado 2500HD, CC SB, 4x4, 8.1L/Allison, 4.10's, Locker, Dual Batteries, 145 Amp alt., Bilsteins
Retrax Rolling Tonneau, Putco SS/Chrome Side Rails, Bushwacker Bed Rail Protectors,Husky Floor Liners

#8 Wirenut

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Posted 11 July 2006 - 02:58 PM

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 :rant: 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.

#9 Cheekster96

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Posted 11 July 2006 - 05:19 PM

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
Lee

2004 Sierra ECSB WT 4x4
Dark Forest Green Metallic
4.8L
3.73s

2008 Nissan Altima SE
Pearl White Metallic
6 speed manual

87 K20
350 TBI
TH400
4.10s

96Z28/SS
383 LT1
4L60E
3.73s

#10 rlarson

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Posted 11 July 2006 - 05:37 PM

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)

#11 Trouttrooper

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Posted 11 July 2006 - 06:27 PM

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
2005 3500 SRW LS Crew Cab Long Bed
8.1/Allison/4:10/locking rear axle

#12 linda

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Posted 11 July 2006 - 09:23 PM

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
My Truck Site
2003 2500HD 4x4 ECSB LT
Whippled 496 @ 7psi
Whipple A2W intercooler

#13 Shooter_va

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Posted 12 July 2006 - 07:34 AM

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.
Posted Image
2001 Silverado 2500HD, LT, 8.1L, Allison, CC, SB, 3:73, 4x4,
Michelin 245/75-16E LTX-M/S2,
Bilstein Shocks,
Spray-in Bed Liner,
Ranch Hand rear bumper,
Husky Mud-Flaps & Floor Liners,
Reese 16K Slider Hitch
2005 Forest River Wildcat 29BHBP

#14 Bart2500HD

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Posted 12 July 2006 - 10:09 AM

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.
2003 Silverado 2500HD, Crew Cab 4X4, Duramax/Allison

2002 Trailblazer LT

#15 dco111

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Posted 12 July 2006 - 11:12 AM

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.




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