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Diesel fuel economy & swap advice

Discussion in '1982-Present GM Diesel' started by C5K5, Jun 8, 2002.

  1. C5K5

    C5K5 Registered Member

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    What sort of fuel economy do you get with the 6.2 and 6.5? I have an 86 Blazer with a 307 gas (12 mpg hwy) and I'm wondering if I can do better either through adding fuel injection or swapping a diesel in. Also, wanting to keep my np205 and 700r4 since I've already invested in their rebuild. Any ideas? What about non-GM diesels like Cummins?

    Thanks-
    Adam
     
  2. Oblin Goblin

    Oblin Goblin 1/2 ton status

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    I get 16-18 mpg with my Blazer. I've heard of people getting better than 20 mpg with these engines but I never have. I probly could if I drove slower than 70 on the freeway though /forums/images/icons/smile.gif As far as keeping your 700r4, you probly could as long as you got a non turbo 6.2. I don't think it would hold up very well behind a turbo diesel though. A cummins diesel would be cool but it would be quite a project. You might consider a 3.9L cummins. It would be alot easier to fit though might be a little under powered. A turbo 3.9L cummins will make more power than an NA 6.2 but not as much as a turbo 6.2. In any case swaping in any diesel would be pretty complicated. Theres alot more to it than just swaping in the engine.
     
  3. René

    René 1/2 ton status

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    between 13,8 and 15,8 mpg.
    In my opinion is worthwhile itself a diesel engine then only if you are looking for an undemanding mule, or diesel fuel is clearly cheaper than gasoline.
     
  4. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I guarantee that you'll be able to almost double your highway mileage with a diesel in your K5, as long as you keep your top speed below 60 MPH and keep you motor well maintained.

    In my 1/2 ton 2WD I can get 28 MPG on long trips, so there's no reason that a heavier 4x4 couldn't get 20-22. What gears are you running?

    I have a 700r4 behind my 6.2. It's done a lot of towing and is still working fine. Once again, regular maintenance is the key to the longevity of a 700r4
     
  5. calcide

    calcide 1/2 ton status

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    I get 16 MPG all the time. On the highway, in the city, with my 37s and with my 31s (I've got 4.10 gears). I didn't get my diesel for the mileage (although that helps), I got it because it has mechanical fuel injection. No computer, O2 sensor, TPS, MAF/MAP sensor, etc.

    The diesel will run better at severe angles than a carb gas motor, without all the CRAP in electronic fuel injection.
     
  6. C5K5

    C5K5 Registered Member

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    Thanks to all for your replies. Haven't really decided yet, but you've given me stuff to think about. I think I'll have a hard time plunking down the dough (and complications) for a different engine if that only buys me (according to most of you) 4-6 mpg, and more only if I make some serious changes in my driving-- no way I'll be keeping it below 60 on the highway, that's for sure! Don't know what gears I have, but it seems pretty spry on 35s.

    thanks again-
    adam
     
  7. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    You might want to consider instead of swapping in a new engine buying a whle new rig. With all that you have to change it might be easier. /forums/images/icons/cool.gif
     
  8. Batmanjr

    Batmanjr 1/2 ton status

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    My 83 came with a 700 behind the 6.2L and it works more reliably than my Honda! I have 31" tires and 3:73 gears and the truck gets 22+ mpg on the freeway and about 18 in town. I'm 22 and no slow go'er so that should tell you something about a diesel. Mine is currently a non turbo, but with a little work and some time, it soon to be! /forums/images/icons/cool.gif
     

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