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diesel advice

Discussion in 'The Garage' started by Steve Harvey, Jul 28, 2005.

  1. Steve Harvey

    Steve Harvey Registered Member

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    Iam thinking of replacing my 350 with a diesel and Iam courious what kind of fuel mileage it will get. I would also like hear from any one who made the switch and how they like it?
    thank you. :k5: :ears: :thinking:
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I get 16.5 mpg with my 6.2 on the highway. 4.56 gears, no overdrive and 39.5" TSL's. The same drivetrain and tires with my old 350 netted me about 9 mpg max.

    The only regret I have is that I didn't do the diesel swap earlier...

    Check the diesel forum here, you won't be able to reply or anything...but you will be able to read through all the posts in there. With a little patience you should find all the info you wanted and more in no time at all.

    Bottom line is that it's not a difficult swap, and it is a worthwhile swap. (In my biased opinion)

    Rene
     
  3. savagek5diesel

    savagek5diesel 1/2 ton status

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    I've yet to gear down my axles but even with 35's i'm still pullin about 14mpg on the highway, before the tire change I was getting over 600 miles per tank, so roughly 20mpg, but that's with alot of city driving too. I say go diesel if you have a good donor. I'm in love with these old 6.2's and 6.5's now, couldn't see myself building another trail rig without it.
     
  4. Robert79K5

    Robert79K5 1/2 ton status

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    Rene always beats me to these posts.....

    Aside from much better fuel economy a diesel has many other characteristics that make it different from a gas engine. Make sure that the intended purpose of your rig is compatible with these characteristics.
    That being said I absolutely love my 6.2 diesel because it does everything I expected it to do, and like Rene, my only regret is that I didn't get around to it sooner.

    Stop on by the diesel board here. Its chock full of good info and experiments people have done.
     
  5. Steve Harvey

    Steve Harvey Registered Member

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    thank you guys!
     
  6. nerraw117

    nerraw117 1/2 ton status

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    i have thought about this swap also. what is a good donor, and arent the 6.2's absolute dogs? i have a 350 and i swear something has to be wrong, for it to be that slow. the more you step on the gas the louder the engine is but you move just like you barely hit the gas
     
  7. dirtwarrior17

    dirtwarrior17 Banned

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    The 350 or the diesel?

    A stock 350 isn't a firebreather but it sure as hell got my rig moving when i wanted it to. I have a corvette shift kit and the PO may have stuffed some gears in her but when i put my foot to the floor it got up and moved.

    I have heard the 6.2's are gutless and they aren't worth it and i've heard the exact opposite. Best way to tell is to drive one yourself.

    the gas guys will tell you diesel motors suck :D and the diesel guys will tell you gas motors suck. Use search and type gas vs diesel..... you'll probably find about 10 threads full of bs and arguments but once you sift through the bickering you should find info your looking for.
     
  8. savagek5diesel

    savagek5diesel 1/2 ton status

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    diesel vs. gas

    before i bought my 6.2 powered diesel i was kinda skeptical about it, but let me tell you that i have yet to regret it since then. It's done everything i've expected from it plus more. I love gas engines, but i love having the diesel in my trail rig. sure it may be a dog on the street, but with a turbo you get a mild 350ci attitude with the bonus of a 6cyl's gas milage. Not to mention is sounds burely as hell when you get a nice exhuast setup.
    And a good 6.2 in my opinion is prolly a military engine because they pulled them out and are selling them with only 20k to 40k miles on them.
     
    Last edited: Jul 30, 2005
  9. 74757685k5

    74757685k5 1/2 ton status

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    I love my 6.2. i have 3 gas blazers and 1 truck of each 3 big manufacturs .i drive the 6.2 the most .It gets better milage with a little less power.I think theyr more dependible and they don't get loaded up with feul going up steep hills.
     
  10. Steve Harvey

    Steve Harvey Registered Member

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    Where can I get info on the used military engines???? Very interested!!!!
     
  11. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Almost all the 350's from the 80's are super slow. You have an '85 also, mine was terribly slow with my 350. Thats kind of a characteristic, you can stomp your foot in it all the way with only minimal more power. A 6.2 should be just as fast as an 85 350 loaded with smog stuff. They aren't that bad of a dog in a lighter vehicle. THey are dogs with weight behind them.
     
  12. darkshadow

    darkshadow 1 ton status

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    they were to some extent because chevy geared them for fuel economy.

    with the right gearing they are great!
     
  13. 6.2LTrailblazer84

    6.2LTrailblazer84 1/2 ton status

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    with the right gearing they are great!

    Does this poor street gearing help them off-road though? Or can changing the gearing improve my deisel off-road as well?
     
  14. dirtwarrior17

    dirtwarrior17 Banned

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    aren't the military 6.2's worse than the street motors?

    The military isn't interested in power unless its comin out of a barrel. They want a cheap reliable motor that will get the job done. I beleive some of the big militrary rigs you see carryin soldiers have a 40 hp diesel in em.
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Gearing for economy does not help you off road, and makes the 6.2 (or any stock motor for that matter) seem more gutless than necessary.

    The military version 6.2's are all non EGR motors which make more power than 6.2's found in 1/2 ton civi trucks.

    If you have a 700R-4 behind a 6.2 I'd use 4.56's even with 31-33" tires. Economy would still be around 20 mpg but it would have a lot more get-up-and-go. For 35's and up I'd run 5.13's. With an OD tranny I think ideal is ~2000-2200 rpm @ 65 in OD.

    Without OD I'd aim for ~2300-2500 rpm @ 65 mph.

    Either way will net you a truck with enough 'snap' to keep you happy, and still get good fuel economy. Off-Road performance will be better too.

    Rene
     
  16. TexasA&Mblazer

    TexasA&Mblazer 1/2 ton status

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    Did all the civilian blazers come with 700r4's?
     
  17. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'm pretty sure if it wasn't all it was close to 99% of them. The military Blazers got the TH400. The civi 3/4 tons and one tons got either the TH400 or the SM465. The motor I bought to swap into my truck was backed by an SM465 from the factory...

    Rene
     
  18. 82K5_6.5L

    82K5_6.5L 1/2 ton status

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    do the swap! u'll love it! i get probably around 15-17mpg w/ my 6.5L, 35's and 4.10s :D
     
  19. lebowski

    lebowski Registered Member

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    http://www.govliquidation.com/ has a lot of military cucv's and other interesting stuff. I just finished putting a military 6.2 in place of my old 305. Runs great so far. No regrets. Right now about. . 20 mpg. A lot better then the 9 mpg the 305 was providing.
     

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