12.7 Detroit need a new turbo (upgrade?), hauling light and best mpg?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Green461, Mar 24, 2020.

  1. harold6091

    harold6091 Light Load Member

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    Dec 25, 2018
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    dash is 100% accurate. i check it every fill up
     

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  3. DDguy

    DDguy Light Load Member

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    Apr 21, 2020
    Ont. Canada
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    Have you installed a 701 or swapped turbos yet ?
     
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  4. maconhadalata

    maconhadalata Light Load Member

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    Dec 11, 2014
    newark, nj
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    Hi. Yes I did. It spools a little earlier and dropped my egt's. Now is really hard to get 900F. But my boost gauge must be ####ed up. It only shows 28 psi at max, no matter what, but I was keeping up with my friend's that reaches 35 psi with the same tune. Mileage is pretty much the same ,6.5 when heavy doing mostly 70mph. With some light loads, even with rain/ wind I got 7.15..cant complain about it!
     
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  5. maconhadalata

    maconhadalata Light Load Member

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    Dec 11, 2014
    newark, nj
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    I will install a new digital boost gauge and see. My friend had the same problem. Will check for boost leak even though my egt is always below 900f . Dont believe my egt and mpg would be that good with a boost leak.
     
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  6. DDguy

    DDguy Light Load Member

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    Apr 21, 2020
    Ont. Canada
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    Great to hear Yes make very sure no boost leaks your tune might not fuel enough to make more then 28Psi boost We do have the 3 stage tuneing Available for anyone interested Basically run 3 power settings with a selectable switch in the cab PM me for more Info
     
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  7. ISXunlike

    ISXunlike Bobtail Member

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    May 12, 2013
    Cortez, CO
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    If your boost gauge is a digital read from the ecm it won’t likely read over 27 or 28 psi for whatever reason Detroit doesn’t recognize numbers over that in their ecm or at least that’s what I was told. When I had mine tuned it would run around 40 on my manual gauge but on the dyno on the computer reading the ecm numbers it was 27
     
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  8. maconhadalata

    maconhadalata Light Load Member

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    Dec 11, 2014
    newark, nj
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    that happened to a friend of mine that has a cascadia.. i think is the same on mine. checking on amazon for a boost gauge.
     
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  9. DUNE-T

    DUNE-T Road Train Member

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    12,327
    May 10, 2015
    Detroit, MI
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    After driving for two weeks with Fernando tune and K31 I finally have some feedback.
    First of all I like k31 way better than 702 turbo. K31 spools quicker and that's what I was looking for. 702 might be better with top end power and higher HP number, but I don't really care about that since I only do regular dry van freight.

    My tune is 550hp/1850tq, the max what my 7045 injectors allowed. My other truck has n14 with 525/1850 and I feel like that's a good power level for the work I do.

    I only did few trips, MI-IL-PA-MI, then MI to upstate NY and back.
    The first trip I had under 20klb in the box the whole time, was driving 70-73 mph the whole time speed limit permitting and got 7.4 mpg

    The second trip was 66mph the whole time , except I80 toll road in OH, where I usually do 70mph. Got 7.95mpg this time.
    The highest number I got before was 7.6mpg doing MI-IL loads

    This week I am doing MI-CO-ND-MI and will have more mpg numbers. We have been doing this lane for the last two years, so it will be interesting to compare to my N14 trucks.

    Power is amazing. When I bought this truck it had factory 430hp and in PA I was not even able to maintain 70mph empty. The speed would drop to 60mph by the time I reach a top of the hill.
    Now with 20klb in the box it has no problem maintaining 70mpg on the cruise control. It just pulls and pulls.

    If this truck had a 13 speed instead of the 10, it would be even more fun to drive through Northeast or go to Carolinas, but still, it's way better than before and I highly recommend going with this setup.
     
    Last edited: Sep 13, 2021
  10. Rideandrepair

    Rideandrepair Road Train Member

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    That is good to hear. I’m disappointed in the 702, only below 1200 RPMs. It’s flat out dead. Seems best at 1500-1650. Then it’s great. Not used to running it so wound up. Can’t be good for mpg. This Truck has never done well on mpg, since new. Stock 500, 7650 injectors. I need to run the first overhead since inframe yet. Otherwise it’s running good. Had a problem with sputtering after idling. Worse when filters were full, but still would do it a little after changing filters. I’ve doused it with algae cleaner and others. Hasn’t done it now for a while. Thought line was sucking air. No idea what the cause was. I suspect injectors weren’t seated well, and some air was getting into the fuel. I’ve heard of Cats doing that, till enough carbon gets built up. I have no idea. Can only guess. Filters weren’t really plugging up. Even after dousing with cleaner. Im Leary of changing too many things at once. Like to know exactly what the problem is. I’ll eventually get a tune of some sort. Economy over power. Need to get overhead ran, and check mpg’s first. That way I can compare numbers for sure.
     
  11. DDguy

    DDguy Light Load Member

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    Apr 21, 2020
    Ont. Canada
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    Do you know which cam you have ? is it 8309 ? or 4912?
     
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