Airflow with big bumper

Discussion in 'Peterbilt Forum' started by matneyenterprises, Jun 2, 2021.

  1. matneyenterprises

    matneyenterprises Bobtail Member

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    Have an 02 6nz powered 379 long hood with a herd bumper. The big one with 4" pipe rated for moose/elk. New 4 core radiator and clean cac and condenser. Also has 11 blade fan. Has a modified "salty" 7cz 600 hp brakeaver file in it, full tilt manifold and borg 78/1.32 turbo.45k on inframe with ipd one piece steel piston kit. I've noticed as we warm up this spring (first spring with the truck) that without the fan on this truck sucks at cooling the water. I can turn the fan on and it makes a big difference. Especially over the factory 8 blade. But it's basically hopeless when loaded in the Colorado hills at 90k+ if you want to stay under 210. So my question is. Is the 379 by design in some way sucky with airflow through the grill/coolers. Or are the 4" bars in front of the grill disrupting airflow enough without the fan on that it's starving? It's done OK so far with the fan on but we haven't got to the hot part of the year yet either.
     
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  3. Roberts450

    Roberts450 Road Train Member

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    Feb 6, 2016
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    What temp thermostats do you have? If the normal 195’s they wont be fully open tell around the 205 mark and the ECM wont tell the fan to come on tell about 217. My 550 2ws is the same way and the truck originally had a X15 cummins in it. Im going to be switching to 180 stats when I get time this summer as I dont like seeing it over 200 ether.
     
  4. matneyenterprises

    matneyenterprises Bobtail Member

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    Sep 5, 2020
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    I forgot to mention, it does have 180s in it. When I'm empty it'll run 175-185 with the fan off for the most part until I start uphill for an extended amount of time, then it'll start to creep up over 200. Especially if I don't get it up to 1700 or higher when it's climbing. Some of that im sure is characteristic of the tune.
     
  5. Concorde

    Concorde Road Train Member

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    Jun 29, 2016
    West Melbourne Florida
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    First, don’t even think about taking the Herd cattle bars off until you price out a new hood.

    Second, everything you have explained seems normal. I’m using my manual fan switch more now that the warmer weather is here too and I got a new 389. When I’m climbing I switch it on around 200..never needed to this past winter.

    My last truck I used the manual fan switch year round anytime I was loaded and climbing.
     
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  6. matneyenterprises

    matneyenterprises Bobtail Member

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    Sep 5, 2020
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    Oh the bumper stays. Haha. I just wasn't sure if it was normal for these 14.6 liter trucks to run warm like it does. Prior to this I was running a 388 we swapped an mxs cat in place of the isx and it was deleted and singled out that had all the power and it never got warm but those acert engines cool waaaay better than the little 14.6 predecessors. I think I just got spoiled haha
     
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  7. lester

    lester Road Train Member

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    NW, Iowa
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    I run a magnum bumper with the vertical bars, can't say I noticed a difference when I put it on ad far as cooling.

    If you can't keep it cool with the fan running I'd say you have other issues. Have you done a water pump?

    I'm around that 700 hp range with my 6nz in a Pete and yeah It heats up fast but no problem pulling temp down with the fan. And my radiator is still original in this 01.

    I think Pete's have about the best air flow for radiator.
     
  8. special-k

    special-k Road Train Member

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    Southern Ontario Canada
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    Is the rad OEM or Chinese or from a rad shop? I replaced my rad a couple years ago. I got it rebuilt at a local rad shop. I trust their work but it runs significantly warmer than the previous one. They also did that one. If lasted 8? years so no complaints there. I just think the new cores don't work as well as the older ones.
     
  9. matneyenterprises

    matneyenterprises Bobtail Member

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    Sep 5, 2020
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    Replaced the water pump and oil cooler when I did the inframe. Maybe it's more in the tuning than the big bumper. I would think I'm somewhere around or less than 700. 600 brakesaver with I'm assuming fuel and timing added. Guy won't say what he did to the file. I know if I let Pyro get over 900/925 even with fan on the water will just keep climbing. That's at 30-34 lbs boost depending on where I'm at in rpm band.
    The radiator was recored by a local guy so I'm not sure how quality his new cores are. We've used several of his radiators in the past and not had an issue but this is our only 6nz. The rest we've done have been in former acert engines. Maybe one of those dimpled setups would be the way to go?
     
  10. special-k

    special-k Road Train Member

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    Southern Ontario Canada
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    Pretty sure the cores are all coming from 1 or 2 wholesalers. I would have went one more row to a 5 core rad in hindsight. I've heard of the dimpled cores but never talked to anyone directly that's run one. Good luck finding out your issues.
     
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