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Cummins 8.3 to M11

Discussion in 'Trucks' started by 72hayes, Oct 31, 2018.

  1. 72hayes

    72hayes Well-Known Member

    May 19, 2011
    road builder
    Kelowna B.C.
    I have a T300 Kenworth with a 8.3 Cummins and was wondering about repowering with a M11.
    It has an Allison trany.
    Has anyone done this?
  2. DMiller

    DMiller Senior Member

    Feb 22, 2010
    Almost Retired
    Hermann, Missouri
    Talking two completely Different engine breeds, different design criteria and different dimensions. The 8.3 is around 1700 lbs. the M11 near to a full ton, physically the M11 is longer wider and taller. Then there is the base difference, you will not achieve the vehicle speed from the 8.3 at 2500rpm going to a M11 at 1800-2000. One is a heavy ton truck typical where the other is used from 2 1/2 to 5 ton trucks and light day cab tractor trailer machines. The Allison may not be compatible with the M11 for shift points and mounting. Will also be cooling system requirements changes.
    56wrench and funwithfuel like this.
  3. Wes J

    Wes J Senior Member

    Jan 24, 2016
    Peoria, IL
    I would think the best place to start would be determining if the M11 was ever offered in a T300. If it was, it can physically be done. Surely money ahead to just buy one ready to go.

    I've driven several tandem dumps with the 8.3. It's a zippy engine when empty. Not enough torque to run loaded on any kind of grade. I once stalled one on a steep hill totally empty. Couldn't down shift fast enough...
  4. petepilot

    petepilot Senior Member

    Jul 7, 2018
    central shenandoah valley va,
    do not think m-11 was available in a t-300