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polar76's avatar
polar76
Explorer
Oct 15, 2018

1997 mechanical Cummins 8.3L Boost question

My 1997 Country Coach did not have a boost gauge and I have been wondering when the turbo should start showing boost.
Over the weekend I installed a "Glow Shift" boost gauge.
On a test drive it did not show much boost till the RPMs got up to around 1600. and then was only around 12psi till the engine got up around 2000 rpms them it showed about 20 psi with a max of 22 psi.

My concern is that the wastegate may not be closing all the way as it will blow a bit of black smoke in the lower rpms when accelerating till the turbo ramps up. I have had the wastegate actuator off and tested at a turbo shop and it functions normally.

All comments right or wrong welcome... :)

Thanks
Wayne
Class A
  • Ivylog's avatar
    Ivylog
    Explorer III
    Oct 16, 2018
    Should have read more carefully. What HP is your 8.3? It’s fairly easy to increase with a different fuel plate... I regrouped my own. I’d say 12 psi on level ground accelerating sounds normal to me. At the same rpm climbing a hill you should see a little higher psi... more HP needed. Mechanical pumps are going to puff a little black smoke when you get on it.
    My electronic injection ISL will only puff a little when I’m above 6-7000’ if I do not ease into it from a stop for some reason. The rest of the time there is no smoke.
  • noteven's avatar
    noteven
    Explorer III
    Oct 15, 2018
    Clicking Check with these people if you have a P7100 injection pump they have some kits.
    https://www.dieselpowerproducts.com/p-9372-tst-power-kit-cummins-83-6cta.aspx
  • polar76's avatar
    polar76
    Explorer
    Oct 15, 2018
    Ivylog thanks for your comments
    You may be confused because the quote you posted
    "And reasonably low boost at cruising speed no uphill grades" was from Brett not me.
    What I said was :
    "On a test drive it did not show much boost till the RPMs got up to around 1600. and then was only around 12psi
    Later I posted , "I am mainly concerned at the lower rpms as it doesn't show any boost while cruising on flat ground at approx 1100 rpm."

    I do get good mileage from 8 to 9 mpg towing (only 32' long coach)
    had it since 2010 and always wondered about the puffs of smoke when stepping on it.
    And of course like many, I'm always looking for more power... :)
  • Ivylog's avatar
    Ivylog
    Explorer III
    Oct 15, 2018
    Having had that vintage 8.3 in a Fl 70 I would say your 20-22 is about right at max acceleration.
    These two statements are confusing..."And reasonably low boost at cruising speed no uphill grades" and "at the lower rpms as it doesn't show any boost while cruising on flat ground at approx 1100 rpm."
    Does it show some boost or not??? 1100 rpms is probably 40 MPH...not much power needed.
    At low power you will not see much boost and some black smoke as you get on it until the turbo spools up. Can't tell how long you've owned, but have you been happy with the power and MPG???
    Sometimes too much info is not good.
  • polar76's avatar
    polar76
    Explorer
    Oct 15, 2018
    Thanks Brett
    Ran the rpms to 2300, this gauge has a recall switch to check the max boost, that is where I got the 2200 psi from. So yes I had it floored but not at the redline of 2550 rpms (on my gauge).
    I am mainly concerned at the lower rpms as it doesn't show any boost while cruising on flat ground at approx 1100 rpm.
    Thanks again I always appreciate your comments,
    I'll check with Cummins.
  • wolfe10's avatar
    wolfe10
    Explorer
    Oct 15, 2018
    Contact Cummins with your engine serial number and ask them.

    And obviously, max boost PSI is only at WOT (Wide Open Throttle), dropping to zero at closed throttle. And reasonably low boost at cruising speed no uphill grades.

    Cummins 800-286-6467

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