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3rd gen cummins. 5.9/48re or 6.7/68rfe?

Discussion in 'Ram Trucks' started by Mark13, Mar 13, 2010.

  1. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,737

    (Yes, another dodge thread from me, I want to be as educated as possible before a purchase is made)

    As the title says I've got it narrowed down to a late 3rd gen, probably an automatic (a g56 isn't totally out yet). For a daily driver, plow/salt truck, tow rig, and play truck which truck would be the preferred one to have? I drive very easy 99% of the time but like to open it up now and then. It would also probably get sled pulled at least once to see if I can beat my friends 6.7. The truck would stay mostly stock but probably get a smarty, exhaust, and maybe a few other mods, probably in the 450-550hp range at the motor.

    2 guys I know have 07.5 6.7s with the 6spd auto. Both have smarty's and dpf delete, one had the egr stuff blocked and removed. Neither seem to have trouble with their trans so far with running them pretty hard and towing up to around 22k. And personally being in one of the trucks while it got 22mpg hwy was pretty neat. Also the exhaust brake and manual gear selection/tap shift is nice.

    I don't know anyone with a late 3rd gen 5.9/auto to see how they like it and their thoughts on the truck. Are the late 5.9 trucks capable of the same hwy mpg at about 65mph? Also what would it take to get a 48re to hold 500-550hp at the motor? (a fully built $5k trans isn't going to happen) I've driven one 07 5.9/auto with about 52k on it, only got to drive it about 4 miles but it seemed pretty nice. I was unable to try the truck with a load on it (either winter equipment or a trailer) to see how the trans did then. Is the 48re as "confused" as the older 47re's are when it comes to picking a gear? I've driven a 95 12v/47re quite a bit and it drives you crazy with the trans, especially pulling a load. Thing will shift gears 5x in a mile while your driving a constant speed on pretty flat ground even with only about 6k behind it.

    With a sibling going away to school in Colorado I'll have a free place to stay on ski trips so my truck will see some miles probably a couple times a year running from N.IL to the Greeley,Co area and then to the mountains. So if the 6.7 or 5.9 is better for fuel by a noticeable amount over the other motor it would sway my decision.

    Whatever I end up with will be getting a 9.2 Boss V and probably a Snow Ex 8500 vbox if that matters to anyone. And I'm looking at trucks in the 30-55k mile range (would be kept to probably 130k+), I average 12-20k a year. The trans would get a new filter and fluid each fall.
     
  2. JohnnyU

    JohnnyU 2000 Club Member
    Messages: 2,040

  3. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,737

    Just posted the same thing there about 3 minutes ago. Also may post it on Comp D.
     
  4. DAFFMOBILEWASH

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,598

    Myself stick with the 5.9 engines. The 6.7's are good but do have a few isseus and are not as dependable as the 06-07 5.9 trucks. My stock 5.9 averages 700-800km per tank even with some light pulling in the mix. Best of all you don't have to unchoke the engines by removing all the polution control stuff to get good milage. Most of all don't look at the overheads for milage they all lie!!! Even more with the chips and stuff.

    The ultimate truck would be a 06-07 5.9 laramie SRW 3500 with leather. Make sure you get leather!!!! Trust me.....
     
  5. sno commander

    sno commander PlowSite.com Addict
    from ct
    Messages: 1,061

    stock for stock the 6.7 is a better package. ill take a built 48re 5.9 with a pac brake over a 6.7 but if you dont want to drop the money on upgrades youll get more with a 6.7 for the same money as a 5.9.
     
  6. rob_cook2001

    rob_cook2001 2000 Club Member
    Messages: 2,181

    I love the 5.9 motor but the 48re is junk unless you want to build it. To hold up to the power you want to make it will need a re-build with upgraded clutches, billet input, valvebody, converter and deep pan. If you want to keep it simple go with the 6.7, throw a smarty on it, ditch the dpf, put a intake on it and a deep pan.
    Robert
     
  7. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,737

    I was kinda leaning towards the 6.7 for those reasons. I like the sound of a straight piped 5.9 more but $ for $ the 6.7 seems to be a better value until you get into making crazy power. I'd take a 5.9 over a 6.7 if I was going with a handshaker but I think I'd rather have an auto. And the G56 seems to be kinda hit or miss sometimes with what it will take stock.
     
  8. cmo18

    cmo18 Senior Member
    Messages: 815

    I have a 06 5.9l and I love it...sure the tranny are known to be weak but every truck has a weak point...With that said, my gf family owns a dodge and we see lots of 3rd gen. dodges come in with 300+km on stock tranny. So IMO its how you drive and your maintenance schedule but if you want to make 450-550hp then you will need a tranny build...The day mine goes,I'lll build it right..

    I too looked at the 6.7l before purchasing mine...what swayed me was when I went for a test drive the engine light came on...I buy a 5.9l over a 6.7l any day...proven motor over and over...the new 6 spd is nice but there must be some bugs in it just like anything else that is new

    DAFFMOBILEWASH 700-800km per tank...thats really good...in that tank of fuel is your truck running at ultimate operating temperatures for most of those miles?

    reason I ask is because everyday I commute back and forth to school at a max of 5 mins of driving-idling...never gives time for the engine to warm up, resulting is poor fuel mileage...1# reason I want summer haha
    CMO
     
  9. nevrnf

    nevrnf Senior Member
    Messages: 456

    If you are planning to Mod it dont expect the dealer to fix it for free. Tooo many people go and hot rod a diesel, then when they have issues they cry that the dealer wont fix it under warranty.
     
  10. cmo18

    cmo18 Senior Member
    Messages: 815

    I forgot to mention, I drove 1000miles in one day, got a consistent 22.5-23mpg hand calculated...
     
  11. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,737

    I've driven both 5.9 and 6.7 and liked them both, if I could get a 5.9 with the 68rfe I'd be all for it. Awesome motor with a cool trans. Or the Aisin trans would be cool.
    I don't expect the dealer to fix something that I caused to break due to a modification. If something breaks and it had nothing to do with me or mods I've done to the truck I'd expect them to fix it even though they will hassle me about it and try and blame me and the mods for the cause of whatever broke.

    I'm not really worried about the motors all that much, more the trans. Cummins seems to have their sh1t together pretty well and make good products 99.9% of the time. I'm more worried about dodge's automatics. I'd really rather not buy a $30k truck and put a tuner, intake, and exhaust and of course guages and then start having trans problems when ever I get on it a little bit (pretty rare). About how much should a 48re be able to take with an aftermarket converter and valve body and a driver who's right foot has an egg under it 98% of the time?
     
  12. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,269

    I think its JPDiepstra or a name like that who did exactly those mod's and says it holds up very well.

    Every diesel is going to show you it's weak link when you start with the modding:

    Ford 6.0- EGR issues, Head problems, Turbo Issue's
    GM- Injector Problems, Trans Problems at higher Horsepower levels.
    Dodge- Injector Pump, Tranny problems (usually start with the Torque Converter).

    If your buying used and are going to mod- than any warranty is gone anyway so I'd do it this way (personally)

    I'd go with a 6.7 and the 68rfe. I'd dump the DPF, and go from there. Seems most issue's with any diesel is the emissions crap. You remove it and most problems go away and mileage returns. I just think the 68RFE or Aisin Tranny is built much better and having 6 gears will always be better than 4. Plus it'll be worth more, and blah blah blah. But you can't knock a 5.9, those motors will go down in history as being as reliable as the sunrise.
     
  13. DAFFMOBILEWASH

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,598

    Speaking of trans.... My 06 has a slight shutter during the first few feet of movement. Both reverse and forward. Is this the tourque converter acting up???? Had the truck in at the dealer for it was lazy shifting between gears too. Had it reflashed and shifts perfect but the shutter is still there expecially when hot!!!

    Since the reflash it is not as good on fuel, but the lie o meter says more..... Dam computers!!
     
  14. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,269

    Definitely bring it in. Usually a shutter is the torque converter and if it starts to go it'll send crap through the rest of the trans.
     
  15. nevrnf

    nevrnf Senior Member
    Messages: 456

    With a torque converter and Valve body you could probably get buy with the Smarty on level 4-5. You would definatly have to use the torque management feature to keep the trans alive. I have a buddy with a 04.5 running just an Edge pressure box (65hp max) and he can slip the converter if he just stands on it. The 5.9 is a much better mileage setup compared to the 6.7.
     
  16. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,737

    Even with all the deletes done to the 6.7 for the emissions stuff and a smarty on it?

    A friend of mine has an 07 qc/sb 4x4, at that time everything was 100% stock besides a 4" turbo back straight pipe, smarty tuner on about 40hp and a egr stuff all gone. I watched him get 22-22.5mpg hand calc'd at about 65. Seems like that would be pretty hard to beat by a whole lot?
     
  17. sno commander

    sno commander PlowSite.com Addict
    from ct
    Messages: 1,061

    seems like some 6.7's are better than others on fuel. it may be possible to get 20+ on the highway but 14-16 is what your mostly going to end up with mixed driving on both motors.
     
  18. GETSOME!

    GETSOME! Junior Member
    Messages: 27

    6.7s have all the emissions junk on them, therefore you aren't going to see as great of mpg out of them.

    450-550 HP at the motor will be easy to hit with a Smarty. Heck, I am at 523HP at the wheels on my 07 5.9. Nothing too crazy in the mods department, just Smarty, AFE intake, straight pipe, and a SB 3600 clutch. Not to mention, its sittin on 37s.
    The 5.9 vs 6.7 question will never die. There are die hard folks on both sides. Both are good motors. With so many vendors coming out with new aftermarket products for the 6.7, it won't be long before they will have the reputation of the time tested 5.9.
     
  19. Mark13

    Mark13 PlowSite Fanatic
    Messages: 5,737

    I'd uncork a 6.7. tuner, egr stuff gone, intake, straight pipe, etc. So all the fuel milage killing stuff would be gone. So I'd assume the fuel milage should be about the same as a 5.9 then.
     
  20. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,269

    I think it simply comes down to the deal you find. Either motor will be great and you obviously are going to tune/modify it to your liking, so any shortcomings will be gone anyways. I'd just be smart about it- if you plan on spending $1000 in mods, or whatever on a 5.9, then make sure some of your money is going to a new converter along with your power mods. A built 48RE tranny can be bullitproof but expensive.

    Good luck and post about a million pictures when you buy!