400 big cam cummins turbo

Discussion in 'Trucks [ Eighteen Wheelers ]' started by bean farms, Aug 16, 2011.

  1. bean farms

    bean farms Light Load Member

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    Feb 25, 2011
    red boiling springs tn
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    i have a a 400 big cam in a dump truck and the turbo has a 27cm ex. housing on it and it spools at 1900rpms and then it only build 18 pounds of boost i have a 23cm ex. housing im wanting to put on it i was wondering what kind of differance whould i see performance wise and all around differance it would make good and bad
     
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  3. V8Lenny

    V8Lenny Road Train Member

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    There's something wrong with your engine. You lose power if you change to 23.
     
  4. SmokinCAT

    SmokinCAT Road Train Member

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    Actully for a true 400hp big cam it should have a 32cm housing on it if it is a holset, the schwitzer chargers are a little different. I was getting 25psi plus out of mine with a 32cm housing and some mild tuning.

    Lenny is right something is not kosher with your engine.
     
  5. bean farms

    bean farms Light Load Member

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    Feb 25, 2011
    red boiling springs tn
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    i dont no what the problem could b it has a new injection pump injectors just ran the over head no boost leaks i had the pump set at 200 pounds of rail pressure and after words i put a #10 button in it it runs good but takes forever to spool the afc screw on the back side off the pump is turned in all the way in also and that made a good deal of diffrance in it i was wondering about the screw in the throttle shaft will it make much diffrance in the power and also there another screw and jam nut above the throttle shaft what does it do and wich way do you screw it to do what the turbo is in good shape just slow spooling and not enough boost
     
  6. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    My Holset HT4 on my old truck wound out to 45 pounds of boost on a 350 BC1. it wasnt stock either.
     
  7. stranger

    stranger Road Train Member

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    Back the hex screw above the throttle shaft out 1-2 rounds. You will see a difference if your AFC diaphragm is not bad.
     
  8. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    He's gonna SMOKE more if he goes.......
     
  9. stranger

    stranger Road Train Member

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    There will have to be some adjustments to get the throttle response and smoke right. If he is having no response, then he either has a bad diaphragm or his AFC screw is too tight. It can be adjusted for good response and very little smoke if played with a little.

    Too far out and all you get is a lot of rattle, lots of smoke, and not much better response.
     
    Diesel Dave Thanks this.
  10. bean farms

    bean farms Light Load Member

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    Feb 25, 2011
    red boiling springs tn
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    i have turned the one above the throttle shaft two rounds but the throttle response sucks and it suckt befor and after i turned that screw out the afc dia. is good whats the screw in the throttle shaft do
     
  11. SmokinCAT

    SmokinCAT Road Train Member

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    It controls the rail pressure.

    You have problems elsewhere, it sounds like the spongy pedal could be from air getting in the system somewhere, if it has never been done new fuel lines from the tank might help.
     
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