8.1L Vortec Gas Mileage?

Discussion in 'GM Gas Engine Rigs' started by turbo_bu, Apr 19, 2005.

  1. turbo_bu

    turbo_bu New Member

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    Been looking at getting a 3/4 ton Suburban with an 8.1L for towing with. Unfortunately, I am a little bit leary of just "how bad" the gas mileage will be. A friend of mine has a Duramax and gets pretty good mileage, but GM doesn't put the Dmax in Suburbans yet :mad:

    Also, if you have some experience with the 8.1L, are you using the 3.73 or 4.1 rear end?
     
  2. Brisk

    Brisk Well-Known Member

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    I worked with a guy who had a cc lb truck with that engine and he sold it to get a diesel because the milage was so bad. I think like 6-8 mpg around town but he has a heavy foot. I think in a burb 10mpg city is possible, but again this isnt 1st hand experiance.

    -Brent
     
  3. DWitcher

    DWitcher Well-Known Member

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    My neighbor has a 2001 Chevy 3500 4x4 with the 8.1 and in town its 9mpg unloaded 12mpg on the freeway unloaded and pulling 10,000lb bumper pull he says the best was 11mpg on the interstate. The thing pulls like a freight train!
     
  4. 502_Jimmy

    502_Jimmy TRC Staff Moderator

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    Thats about what my 8.1L 2500HD got. I never got 11 towing though... more like 7-8mpg.

    John
     
  5. RJF's Red Cummins

    RJF's Red Cummins TRC Staff Moderator

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    And unfortunately, they never will.

    I would take 3.73's. The slightly higher ratio would promote a little better mileage on the highway and the power of the engine would be plenty to pull most loads you would find behind a Suburban.
     
  6. turbo_bu

    turbo_bu New Member

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    Thanks for the feed back guys.... I have also been reading some other information that the 8.1L used to (still does?) have an oil consumption problem. Anyone else heard of this?
     
  7. RJF's Red Cummins

    RJF's Red Cummins TRC Staff Moderator

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    I've heard of it and have even heard of one guy that went through a quart every 1K.
     
  8. 502_Jimmy

    502_Jimmy TRC Staff Moderator

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    Mine went through only a qt in 3k-3.5k miles. I attributed this to the large displacement.. :confused:
     
  9. Resqpink

    Resqpink Member

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    I've got an '03 Suburban 2500 4x4 w/33s. We get 10mpg in town, 13.5 unloaded hwy (this is all sea level, 80 mph). Predator programmer boosted mpg @1.5. And yes, it pulls like crazy! It's hard to believe an aerodynamic brick will move like this thing does! Just bought an f-250 diesel for better mileage, but it's not nearly as fast in stock form. Mine burns a quart of oil every 2500-3000 miles.
     
  10. thehurtster

    thehurtster New Member

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    I have a 2001 Silverado 3500 with 8.1L and a allison trans with 4.10 gears.It gets 11.5 empty and 8 loaded.And yes they pull like crazy. I would like to learn more about that predator programmer that gained 1.5mpg.
     
  11. Resqpink

    Resqpink Member

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    I've still got it, sold the suburb. Could make you a deal...but if I remember correctly, it won't work because mine didn't have the allison.
     

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