444xt Cummins First post, the good, bad, and ugly of a 444xt Cummins.

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Manurehauler, Feb 9, 2010.

  1. cummins everything

    cummins everything Bobtail Member

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    I like to ask questions because that’s how you learn things.
    Now I can’t see how it’s a dream given the size of the turbo inducer compared to the N14 turbo.
    And I say that because I had my N14 turn up a lot and with the stock turbo and it was consistent 47psi and definitely no pushover.
    Also I do my own tuning
     
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  3. ironeagle2006

    ironeagle2006 Road Train Member

    The engine in question wasn't stock when she was making that boost. She had been overhauled to about double the stock horsepower and ate 550 Caterpillar engines for breakfast on any hill or mountain we hit. She had enough power to just about lift the right front steer off the ground when you gave her everything she had. The other driver's in the company called it Rose's grin. The turbo we used was a custom one were the turbine section was undersized for the compressor. It could spin faster building more boost than it should have been able to. We basically put a 4 series holsett turbine into a stock 3 holsett housing. Instead of max of 50 we got 70. But my boss at the time had a mechanic that literally could build or repair anything and a fully equipped machine shop. I mean he literally pulled out the blocks of all the trucks and recut the sleeve bores if required line honed cranks heck he even had the capability to regrind cranks in his shop. That give you an idea of how extensive he was setup. The only thing that wasn't rebuilt in house for the fleet was rear ends as the costs of the parts was more than he could get them from a rebuilder.
     
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  4. cummins everything

    cummins everything Bobtail Member

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    Thanks again for the info.
    I did the same thing with a holset hx55. It came with a 22 centimeters squared turbine housing to run on the ism11 and I had a L10 that was turn up to all and then some so i ran the HX55 but I put a smaller backend on 18 centimeters squared to be exact and that was pushing 45psi on that little L10 and believe me it was one of the Craziest trucks on the streets here. No cat,N14 or Detroit was coming around that. Keep in mind I’m talking about dump trucks.
    The L10 was in a 91 Daf
     
  5. SmokinCAT

    SmokinCAT Road Train Member

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    Check the oil, if the oil is dirty and the previous owners have went extended intervals on oil changes then you may have issues with the STC down the road.

    The STC system loves clean oil, so many got a bad rap from people just neglecting them.
     
    k100 4 ever and black_dog106 Thank this.
  6. SmokinCAT

    SmokinCAT Road Train Member

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    Why are they king? Maybe because they were the only one, but this day an age people are figuring out that their setups weren't that reliable, the retarded timing to lower operating rpm was a horrible idea, the 855 loves rpm and them pushing people to run 1400rpm burnt a lot of engines up over the years.
     
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  7. SmokinCAT

    SmokinCAT Road Train Member

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    50psi is a walk in the park, the turbo offered on the 444 was more than capable of taking a lot of extra fuel.

    Most cats came with 73-75mm compressor inducers, the HT4 on the 444 has a 88mm inducer, that charger is capable of 900hp easily.
     
  8. SmokinCAT

    SmokinCAT Road Train Member

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    You guys are comical
     

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  9. k100 4 ever

    k100 4 ever Bobtail Member

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    Aug 25, 2021
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    thank you for proving what i thot . i have an 88 444 in a k100 i was wondering what kind of change from 20 psi boost under load and no more than 850 pyro on long pull .i have a #10 pull button to install but i would like to add it burns clean works pretty impresive pulling 90,000 payload is slow on hills when you start dropping gears . oh ya it was 45 psi oil and i installed a flatt washer in the oil pump it increased oil psi to over 50 when old but 48 to 55 when pulling it seemed to have way more pull with the higher oil psi. sorry for ramble
     
  10. SmokinCAT

    SmokinCAT Road Train Member

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    It sounds like you may have some fueling issues, that boost is low even for a stock 444, you should put a gauge on it and check fuel pressure under load.
     
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  11. k100 4 ever

    k100 4 ever Bobtail Member

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    Aug 25, 2021
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    i put teflon braided stainless fuel lines and only running a fass pump i am going to change the filters today and see if i can get a gauge on the fuel psi thanks for your info . i will keep you updated i used to hear how bad the 444 was and i ended up with 1 that just had a fresh rebuild still looks like new and makes #### loads of power with low turbo boost i cant with to see what that # 10 fuel button will do but i wont change it untill the boost comes up .for all the people that heard they where junk they just passing along the hearsay .they probaly dont like cabovers ether.
     
    Last edited: Aug 26, 2021
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