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Ok guys diesel time.

Discussion in 'The Garage' started by sho_shane, Jan 10, 2007.

  1. sho_shane

    sho_shane Registered Member

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    Well im reading on doing a diesel swap. Im trying to find a 6.2 doner truck then it will be on :)

    I just want to know how gutless a 6.2 be in my k5 with 308 gears, on 35" tires? And what kinda milige will I get?
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    It will be flat out gutless with your ratio/tire combo. As would a 350, 305, and even a 454. Not to mention you'll likely burn up an auto trans with that setup.

    Mileage will be low in town probably below 15. I'd be doing some sort of a gear change before an engine change.
     
  3. sho_shane

    sho_shane Registered Member

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    I need that hiway gear. What rear combo do yall think I need to go with? even for my gas setup for right now. I mean it feels good to me when i drive it? Wit hthe setup I have now the guy told me that he was getting 13-15mpg. But i think im going to do a swap later this year and im just trying to figer out if a diesel would be better.

    The prob for me is, Does the better mpg of the diesel out do the higher cost of fuel over a gas motor?
     
  4. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    fwiw... i've gotten 18+ w/ my 6.2 on the highway. this is having the 6.2 w/ a non-overdrive manual transmission (1:1 ratio) and 4.10 gears. you will NOT be happy w/ 35's and 3.08's. what tranny do you have? w/ a non-overdrive automatic, i'd expect a mile or two per gallon lower. if you really need your fuel economy, go to at least 3.73's and a 700r4 - but i'd recommend at least 4.10s. you could probably get 20 highway w/ the 4.10s and better with the 3.73s, assuming everything is healthy. make sure it's a strong rebuilt 700, aand it is MANDATORY that your tv cable is set properly.

    it can outweigh the cost of the gas engine. it all depends on what kind of mileage you get out of your gasser... which can vary a ton depending on whats done with it.
     
  5. sho_shane

    sho_shane Registered Member

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    I really dont know how much im getting with my gasser. Again I was told that it would get 13-15mpg with my setup. Like gas right now is 2.09 a gal and diesel is running 2.35 a gal.

    Im just looking for a motor that will let me drive my truck every day. I know that I have a tall, heavy truck with big tires. SO im not going to get great mileage out of it. But i want the best I can get with out taking out alot of power or drivabilaty.

    On top of that I like the big smoke cloud you can get out a diesel :D
     
  6. stallion85

    stallion85 1/2 ton status

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    with the information given I would just stick with your gas engine. The cost of swapping in a diesel, changing gears, and the increase in fuel price of Diesel vs Regular Unleaded would take years to break even let alone be more economical.
     
  7. stallion85

    stallion85 1/2 ton status

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    The only great benefit I see out of a Diesel (both of mine are Diesel) are major power plants (Newer Diesels). Of course you do see better mileage numbers, but at .35 more a gallon is it really worth it?

    BTW I have a Dodge Cummins and average 13 in the city and 18 on the highway.

    In my M1008 with the 6.2 I haven't even bothered to figure out what kind of MPG I am getting with 42's and 4.56. The M1008 is a toy anyways......
     
  8. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Ok, as far as the gears.... You might as well just try and start out in hi gear, and forget 1st, 2nd. Thats the same effect of having a way high ratio like you have going on.

    The diesel engine will easily compensate for the higher price of diesel.

    If you are good, I'd swap in a Cummins 4BT. People think 6.2's are so good on fuel compared to the high powered turbo diesels.... they are NOT. People forget that 6.2's get 25mpg in a 2wd C10 with a 700R4 that weighs 4,400lbs.

    A 6.2 in a K30 CC dually gets mid to higher teens, where most Dodge Ram owners get 20+mpg out of 6 cylinder Cummins motors.

    You'll get low 20's with a 6.2 and an overdrive trans, very low 20's. You'll get mid 20's+ with a 4BT, and essentially have more power and a better engine.

    This is all figured with proper gearing of course.

    Cheapest route..... just put gas in the truck and go...
     
  9. uglytruk

    uglytruk 1/2 ton status

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    Look up muddybuddy, 6.2's are s l o w. Get a turbo or get used to it...
     
  10. sho_shane

    sho_shane Registered Member

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    Ok well with my gas setup, What kinda mpg would I get if i steped it up to a 373 gear?
    Heres my setup please let me know what you think. I wish i could figer it out myself but I have no spedo. so here goes:
    350 motor
    T350 trans
    NP203 transfer (saving up for a 205)
    4"SL
    3"BL
    35" tires

    So what should I be pulling with this setup if I had 373's
     
  11. stallion85

    stallion85 1/2 ton status

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    to be honest if you are so concerned with fuel economy run away from old chevy trucks and get a ricer......or at least some cheap toyota to dd in.
     
  12. uglytruk

    uglytruk 1/2 ton status

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    I prefer the 203 for my environment... Sell me yours? Like I need another one...
     
  13. uglytruk

    uglytruk 1/2 ton status

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    Bull, the old saying if you have to ask... BS!

    My 6.2, TH400- 4.10's gets 14 mpg. Can't wait to see what odrive does to it... Even cruising 60 and under, sometimes well under!

    My tired 6.2, Banks, 700R4 3.73's got 19-21. Real mileage, not a guess...
     
  14. grimjaw

    grimjaw 1/2 ton status

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    What size tires? I am playing around with a Gear Ratio Calculator before building my M1028. 2100 rpms is my goal at 75 mph.
     
  15. bear76

    bear76 1/2 ton status

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    There is always somone who will tell you to stay away from full size trucks if you want MPG. There are proven ways to get decent MPG's, all include diesel and OD. Keep your gears low, matched to your tranny for best rpm's at speed.

    I think it would be cool if we could start some type of race or compition for the best MPG's in a K5 while still driveable and offroadable.
     
  16. uglytruk

    uglytruk 1/2 ton status

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    Here, hear... Odrive is the only way...
     
  17. imiceman44

    imiceman44 1 ton status

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    Well that one I would win.
    30MPG with a 5.9 TD in a K5 :D
    3.08 gears and 35" tires.
    415 ft lbs of torque moves this thing good and the manual tranny saves me from trouble.
    :D
     
  18. BKinzey

    BKinzey 1/2 ton status

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    30 :eek1::eek1: That is impressive! I was going to say I got 25 mpg for highway on a 900 mile trip w/ 6.2, 3.43, 700r4 and 32" tires. So of course I took it apart:haha:

    If I wanted mpg though at this point instead of the 6.2 I'd go with the 4BT. If you look you can find them cheap and are easily modded for more power. I'm convinced the 4BT will out perform the 6.2 and get better mpg to boot:D

    After all my research I found lots of suggestions you could get 300hp out of the 4BT but didn't find anybody who actually did! A few did suggest don't expect it to last long at 300hp:doah: I do think 200hp is reasonable.

    Where is Leonard anyway? Frito-Lay used 4BTs on a GM bell housing for their trucks so might find 'em cheap there.
     
  19. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Bingo, people think the 6.2 is such a fuel saver....


    Might as well push that cummins out to 325HP and 700+ft lbs, won't hurt mileage, and will make you smile a lot more...that or get you killed...:haha:
     
  20. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    You essentially can. Mainly with a P-pumped 4BT. It's pretty simple, a 4BT set at 300HP is like a 6BT set at 500HP. People have 500HP Rams all day long. With that kind of fuel and boost, head gasket work can be needed.

    All you need to get 300HP out of a P-pump 4BT. Extrude hone the injectors, flow them twice. A different fuel plate, and an HY35 or preferably an HX35. I would use a Marine headgasket with 12mm studs too, just in case.

    Far as I know, all the parts are the same between a 4BT and 6BT. You could likely buy injectors and different performance items for a Ram cummins and just have cylinder type parts left over.
     

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